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An in depth look at the Roland Jupiter 8's VCO
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author An in depth look at the Roland Jupiter 8's VCO
Jackdamery
So I took the liberty of copying out the VCO-1 from the Jupiter 8 schematics and cleaning it up a bit in MS Paint.



It's a saw core, based on integrator/schmitt trigger design. Frequency is controlled by a voltage to current sink expo converter.

Original Parts List
Semiconductors:
1x CA3046 NPN array //Available surplus/ebay
1x 4558 dual opamp //Still manufactured
2x TL080 single opamp //Available surplus/ebay
1x NF510 (FET) //Impossible to find, suggested replacement 2N4393
1x 2SA1015- GR (PNP) //Still available via surplus/ebay
2x 1S2473 diodes. //No longer made, sometimes available via surplus, read online that it can be subbed with a 1N4148, although might not match for this purpose.

Other:
1x 1K TSP102J temperature sensing 'posistor' //Available as pulls/NOS from Littlediode.

Resistors:
It seems that MF stands for 'metal film' ie 1% tolerance resistors where stability is critical in the circuit.

Trimmers:
BMF ? Not sure what B stands for but do metal film trimmers exist?
1x 100k - Tune
1x 2k - Width
1x 5k - Linearity

Capacitors:
Either listed as 'p' for picofarad or 'c' for microfarad. C6A is a 1000pf polystyrene for timing stability.

New Parts List
Semiconductors:
1x LS318 NPN array
1x 4558 dual opamp //Still manufactured
2x TL071 single opamp
1x 2N4393 (FET)
1x 2N3906
2x 1N4148
1X 1K Tempco
How the VCO core works



As I understand it, the integrator charges the capacitor in the feedback loop, so the output is a rising ramp. When the voltage reaches ~10v the schmitt trigger/comparator goes fully positive with a narrow pulse at 26v p-p. This is more than the breakdown voltage of the diode in its path so the pulse hits the gate of the FET, opening it as an easier path for the current to travel than through the charging capacitor. It also hits the second diode opening the path for ground, discharging the capacitor and reseting the comparator. The cycle then repeats.

Could this be made with currently manufactured components?

The CA3046 NPN array is no longer manufactured. However, other NPN pairs are still available (The LS318, for instance). The Jupiter doesn't seem to make use of the remaining parts of the 3046 as a temperature sensor and heater as some other synths do, so really all that is needed is 2 NPNs.

The 'posistor' as far as I can tell is a resistor that increases in impedance relative to rising temperature. You can still buy these, mouser sells 560 ohm ones which are used in the VCF of the Jupiter. I'm not sure what the TCR of these is though as there is no info provided. I believe the 3300ppm TCR tempcos usually used in SDIY are negative coefficient, but perhaps the circuit could be adapted to use them instead.

The TL080 is a JFET input opamp. It's no longer manufactured, but National Semiconductor do make one, the LF411. It looks like the 10pf capacitor between pins 1 and 8 set the bandwith of the integrator TL080, this might be important, I'm not sure. Maybe someone here could suggest a better replacement.

It seems like this design could indeed be resurrected at least fairly closely to the original. Comments/corrections very welcome.

TL:DR - here's a JP8 schematic, let's make one.
roglok
Quote:
Other:
1x 1K temperature sensing 'posistor' //Impossible to find, not sure exact properties and spec.


Little Diode stock the original thermistors:
http://www.littlediode.com/components/TSP102J.html
filterstein
Thonk has the tempco's: http://www.thonk.co.uk/product-category/electronic-component/tempco/

About the NF510 substitute: never found out what the recommended fet is.
Heard 4092 and mpf102 as succesfull replacements too.

Remember that the JP8 is microprocessor controlled, the autotune could correct when it drifted out of tune.
2thick4uni
I think I'd replace the 4558 with a dual precision op amp such as LT1013, won't affect the sound at all but will reduce drift in the summer and expo converter. Likewise replace the 3046 with LS318 or similar or even match a pair of BC547's or similar. The transistors in the 3046 are only matched to about 3mv, you can hand match transistors closer than this. Any 1k 3300ppm or 3500ppm ptc tempco should be fine. Multi turn cermet trimmers will be ok too. I'm sure there will be a few fet's that will work ok, best way is to model the circuit in Ltspice and see what works.
Jackdamery
roglok wrote:
Quote:
Other:
1x 1K temperature sensing 'posistor' //Impossible to find, not sure exact properties and spec.


Little Diode stock the original thermistors:
http://www.littlediode.com/components/TSP102J.html


Cool thanks. Since your post I ordered and received two of them. Just tested on in the office with the DMM. It's starting impedance was 980Ω. As I placed my finger on it, it increased incrementally to 985Ω. Then took it off and it lowered back down to 980Ω.

This 980/1k is in series with a 390Ω in the circuit, making 1.390KΩ which is of course scaled down, as it's in parallel with a 3.3kΩ.
Peake
2thick4uni wrote:
I think I'd replace the 4558 with a dual precision op amp such as LT1013, won't affect the sound at all but will reduce drift in the summer and expo converter. Likewise replace the 3046 with LS318 or similar or even match a pair of BC547's or similar. The transistors in the 3046 are only matched to about 3mv, you can hand match transistors closer than this. Any 1k 3300ppm or 3500ppm ptc tempco should be fine. Multi turn cermet trimmers will be ok too. I'm sure there will be a few fet's that will work ok, best way is to model the circuit in Ltspice and see what works.


"Stability" =does= affect sound in that the beats and tracking become more predictable and less slightly randomized. The resultant sound is more mechanical, especially in a polysynth. This is why Ensoniq etc. put a "Humanize" randomization feature in their LFOs, for example. (Repeating if it's not "gotten"..."sound" means what you hear and how you respond to it.)

Don't fall into the trap of "improving" something which already interests you for exactly what it is. Don't "fix" it if it isn't broken.
thetwlo
didn't know the 3046 was discontinued.
fwiw: Tayda still sells them:
http://www.taydaelectronics.com/catalogsearch/result/?q=ca3046
2thick4uni
Peake wrote:
2thick4uni wrote:
I think I'd replace the 4558 with a dual precision op amp such as LT1013, won't affect the sound at all but will reduce drift in the summer and expo converter. Likewise replace the 3046 with LS318 or similar or even match a pair of BC547's or similar. The transistors in the 3046 are only matched to about 3mv, you can hand match transistors closer than this. Any 1k 3300ppm or 3500ppm ptc tempco should be fine. Multi turn cermet trimmers will be ok too. I'm sure there will be a few fet's that will work ok, best way is to model the circuit in Ltspice and see what works.


"Stability" =does= affect sound in that the beats and tracking become more predictable and less slightly randomized. The resultant sound is more mechanical, especially in a polysynth. This is why Ensoniq etc. put a "Humanize" randomization feature in their LFOs, for example. (Repeating if it's not "gotten"..."sound" means what you hear and how you respond to it.)

Don't fall into the trap of "improving" something which already interests you for exactly what it is. Don't "fix" it if it isn't broken.


Yep, a good point and could be interesting to pursue this further. I was just trying to clean it up a bit as you'd be losing the benefit of autotune if using it as a stand alone vco, perhaps precision op amps will make it too accurate and sterile. I think that, as you say, instability is one of the reasons we love old analog gear so much and it needs to be preserved. However, thermal instability isn't particularly musical when it throws you out of tune in the middle of a performance as so many early minimoog users know all too well. Closely matched exponential transistors and correct tempco seem to be the key here, surely its possible to have thermal stability and still keep a bit of organic drift? So, how about keeping the 4558 and just addressing thermal drift by better matched expo transistors?
Jackdamery


Here's a page from the Siloconix transistor reference book suggesting the 2N4393 as a replacement for the N510 FET.

(Original link)
http://www.datasheetarchive.com/dl/Scans-026/ScansUX9527.pdf

Today I showed the schematic to my colleague who has some 40 years of experience as an electronic engineer, a lot of it with analogue circuits. He made a lot of calculations on the spot including one (CV = IT) ? Googling CV & IT turns up a lot of programming jobs though obviously cry A lot of what he said went over my head but seemed to make sense.

He calculated the maximum frequency possible from this oscillator to be 160kHz.

With regards to the FET he said the saturation drain current (IDss) should be 10mA. In this circuit the gate-source cutoff voltage(VGS(off)) should be 10v. So for this purpose a 2N3819 should work too.

He was curious as to the reason for the comparator and the PNP transistor connected to the long tail NPN pair of the 3046 on the expo converter. Any ideas?

Also he was asking why a tempco was necessary when the transistors being monolithic should compensate eachother nicely.



RE: the trimpots. VCO1 tune sets the rough starting tune. In the real synth the computer would then finely 'tune' it by varying the voltage fed to it from the DAC. VCO1 width sets the range of frequency it can cover. The first opamp is a DC signal mixer and this pot sets the gain of it - a larger gain equals a wider frequency. VCO1 linearity is for tuning the 1v/octave response of the expo converter.
filterstein
[quote="Jackdamery"]

Here's a page from the Siloconix transistor reference book suggesting the 2N4393 as a replacement for the N510 FET.

(Original link)
http://www.datasheetarchive.com/dl/Scans-026/ScansUX9527.pdf

Thanks, thats a great find!
2thick4uni
A feedback loop to the op amp is formed by one of the matched pair transistors, R12 and the third transistor emitter base junction. As it has a feedback loop it is not acting as a comparator, it also has a cap across it which acts as an integrator. I think the op amp's purpose is to control the current through the expo convertor, quite common in VCO's. I've seen a transistor at the base of the long tailed pair in there as well (early minimoog oscillator for example) but have no idea what purpose it serves! A tempco is still required even though a monolithic matched pair is used, it compensates for scale drift which is about -3300ppM/C, by using a PTC with 3300ppm/deg c it nulls this out.

Can anyone with a more thorough understanding of this schematic step in and give a full explanation of the circuit? I'm intrigued as to why a 3k3 resistor (R14) is parallel to the tempco, is it because the tempco has a larger compensation coefficient than 3300ppm and this pulls it down?
Jackdamery
2thick4uni wrote:


Can anyone with a more thorough understanding of this schematic step in and give a full explanation of the circuit? I'm intrigued as to why a 3k3 resistor (R14) is parallel to the tempco, is it because the tempco has a larger compensation coefficient than 3300ppm and this pulls it down?


Well yeh, that's what my esteemed colleague said. He reckoned it should scale it down to half.
Jackdamery
Also regarding the TSP102J. I nicked this quote from the Roland Jupiter forum. Here is a mention of it in a patent for a clothes dryer. It says it's coefficient is 0.7% per degree celcius.

Quote:
Although other similar devices may readily be utilized, in the preferred embodiment sensor 24 is a manufacturer's type TSP102 thermistor, obtainable from Texas Instruments Corporation, P.O. Box 225474, Dallas, TX 75265. Sensor 24 is preferably a positive temperature coefficient thermistor having a nominal 1000 ohms resistance at 25.degree. C. and a linear coefficient of 0.7%/C..degree.. Sensor 24 is located so as to be sensitive to drying air temperature, and will exhibit a change in resistance linearly proportional to the sensed temperature.


http://www.freepatentsonline.com/4275508.html

I forgot to mention earlier the TSP102Js I received yesterday are packaged in a TO-92 transistor case with only two legs. One of them seems to have the stub of the middle one left though. They seem to have come from different sources though as the lettering is different on each.
Peake
2N4393 are easily availalble on eBay but PN4393 are much less expensive. Surplussales have 2N for $0.79 each:

http://www.surplussales.com/Semiconductors/Transistors-SCR-2.html
Dr. Sketch-n-Etch
PN4391 is very commonly used for VCO reset duties in the synth DIY world. I have a small pile of them in my garage.
2thick4uni
Jackdamery wrote:
Also regarding the TSP102J. I nicked this quote from the Roland Jupiter forum. Here is a mention of it in a patent for a clothes dryer. It says it's coefficient is 0.7% per degree celcius.

Quote:
Although other similar devices may readily be utilized, in the preferred embodiment sensor 24 is a manufacturer's type TSP102 thermistor, obtainable from Texas Instruments Corporation, P.O. Box 225474, Dallas, TX 75265. Sensor 24 is preferably a positive temperature coefficient thermistor having a nominal 1000 ohms resistance at 25.degree. C. and a linear coefficient of 0.7%/C..degree.. Sensor 24 is located so as to be sensitive to drying air temperature, and will exhibit a change in resistance linearly proportional to the sensed temperature.


http://www.freepatentsonline.com/4275508.html

I forgot to mention earlier the TSP102Js I received yesterday are packaged in a TO-92 transistor case with only two legs. One of them seems to have the stub of the middle one left though. They seem to have come from different sources though as the lettering is different on each.


I've had another look at this and done some simple calculations.

Ok, so we now have the temperature coefficient for the tempco. ppm is 10,000 times smaller than deg c, so the tempco is actually 7,000ppm/deg C. This is more than twice as large as needed, hence R14.

So we have 1000R + 390R /3300R = 0.4212
If we multiply 7000ppm by this it gives 2948ppm/c

And if we assume the 3k3 resistor is metal oxide it will have a coefficient of around 300ppm/c which we need to add in.

So, 2948 + 300 = 3249ppm/degC

Which is pretty close to the ideal 3,300ppm/degC needed to compensate the expo transistors.

The combined parallel/series combination of R13 + R15 / R14 is actually 978R, which is not a bad approximation of 1K.

So, R13, 14 and 15 can be replaced with a single 1K 3300ppm/c tempco! There should be sufficient adjustment on VR2A to get compensate for 1K rather than 978R.

My guess is that when the JP8 was designed these TSP102 tempco's were cheaper and or more readily available than 1K 3300ppm parts.



.
Jackdamery
2thick4uni wrote:
Jackdamery wrote:
Also regarding the TSP102J. I nicked this quote from the Roland Jupiter forum. Here is a mention of it in a patent for a clothes dryer. It says it's coefficient is 0.7% per degree celcius.

Quote:
Although other similar devices may readily be utilized, in the preferred embodiment sensor 24 is a manufacturer's type TSP102 thermistor, obtainable from Texas Instruments Corporation, P.O. Box 225474, Dallas, TX 75265. Sensor 24 is preferably a positive temperature coefficient thermistor having a nominal 1000 ohms resistance at 25.degree. C. and a linear coefficient of 0.7%/C..degree.. Sensor 24 is located so as to be sensitive to drying air temperature, and will exhibit a change in resistance linearly proportional to the sensed temperature.


http://www.freepatentsonline.com/4275508.html

I forgot to mention earlier the TSP102Js I received yesterday are packaged in a TO-92 transistor case with only two legs. One of them seems to have the stub of the middle one left though. They seem to have come from different sources though as the lettering is different on each.


I've had another look at this and done some simple calculations.

Ok, so we now have the temperature coefficient for the tempco. ppm is 10,000 times smaller than deg c, so the tempco is actually 7,000ppm/deg C. This is more than twice as large as needed, hence R14.

So we have 1000R + 390R /3300R = 0.4212
If we multiply 7000ppm by this it gives 2948ppm/c

And if we assume the 3k3 resistor is metal oxide it will have a coefficient of around 300ppm/c which we need to add in.

So, 2948 + 300 = 3249ppm/degC

Which is pretty close to the ideal 3,300ppm/degC needed to compensate the expo transistors.

The combined parallel/series combination of R13 + R15 / R14 is actually 978R, which is not a bad approximation of 1K.

So, R13, 14 and 15 can be replaced with a single 1K 3300ppm/c tempco! There should be sufficient adjustment on VR2A to get compensate for 1K rather than 978R.

My guess is that when the JP8 was designed these TSP102 tempco's were cheaper and or more readily available than 1K 3300ppm parts.



.


Excellent analysis! Are you really too thick for Uni? Also lol at the Viz quotes.

One point to mention though is aren't tempcos usually used in expo converters NTC? The TSP102J is PTC. Is it important which way it compensates as long as it does move relative to temperature?

Tempcos are usually placed in the negative feedback path of the signal mixing opamp of the expo converter aren't they? Whereas this one is acting a voltage divider on the output of the mixer.

So an NTC in the feedback of an opamp would reduce the value of the resistor with an increase in temperature. Gain in an inverting amplifier is R2/R1, so assuming R1 is a 100k resistor: 1/100 = 0.01 gain. If the tempco drops to 950ohm with an increase in temperature then 0.950/100 = 0.0095 Thus lowering the gain with an increase in temperature to keep the scale correct.

Assuming the gain is constant in the JP8 mixer opamp, then our temperature compensation is in the form of a voltage divider.

following the opamp we have 10k resistor as R1 of the divider and then say we follow it with R2 as a 1k tempco Vout R2/(R1+R2).Vin so say our input voltage is 1v : with R2 at 1K we have an output voltage of 0.091V. If the tempco increases with temperature to say 1050 ohms then the output voltage will be 0.095v Thus, in this circuit gain increases with temperature
2thick4uni
Jackdamery wrote:


Excellent analysis! Are you really too thick for Uni? Also lol at the Viz quotes.

One point to mention though is aren't tempcos usually used in expo converters NTC? The TSP102J is PTC. Is it important which way it compensates as long as it does move relative to temperature?

Tempcos are usually placed in the negative feedback path of the signal mixing opamp of the expo converter aren't they? Whereas this one is acting a voltage divider on the output of the mixer.


Yes, I really am too thick for uni, I have the exam results to prove it!

PTC tempco's are the usual type in expo convertors for vco's, the much loved PTC146 is PTC.

http://www.elby-designs.com/contents/en-us/tempco.pdf

Do try one in the circuit and let us know if it works.
2thick4uni
Forgot to answer second part of your question. A PTC works here because it is at the bottom half of the potential divider coming from the output of the op amp, so as its value increases it will increase the voltage from the op amp into the base of the expo transistor (as R7a, the other part of the potential divider, doesn't change). If tempco was at the top of the potential divider or took the output directly from the op amp it would reduce the voltage on an increase in temperature, so would then need to be a NTC component.
Jackdamery
2thick4uni wrote:
Jackdamery wrote:


Excellent analysis! Are you really too thick for Uni? Also lol at the Viz quotes.

One point to mention though is aren't tempcos usually used in expo converters NTC? The TSP102J is PTC. Is it important which way it compensates as long as it does move relative to temperature?

Tempcos are usually placed in the negative feedback path of the signal mixing opamp of the expo converter aren't they? Whereas this one is acting a voltage divider on the output of the mixer.


Yes, I really am too thick for uni, I have the exam results to prove it!

PTC tempco's are the usual type in expo convertors for vco's, the much loved PTC146 is PTC.

http://www.elby-designs.com/contents/en-us/tempco.pdf

Do try one in the circuit and let us know if it works.


Do you think this would work?

http://uk.farnell.com/te-connectivity-citec/lt300014t261k0j/resistor-t emperature-sensing-1k/dp/1174306?whydiditmatch=rel_3&matchedProduct=73 2278

Also for breadboarding, I'm thinking of subbing the TL080 for a TL071, as it's also a JFET input single opamp. Do you think this would be ok?
2thick4uni
That tempco will be fine, not perfect but near enough, I know a few people have used these for vco's and they have performed well. If you are in the UK I can send you a 3300ppm 1k tempco, I have a few spares.

The TL072 should work ok, but do be aware that the 10pf capacitor will not then be connected to anything as the TL080 has a different offset null arrangement to TL081 and TL071. Pin 8 is comp on the TL80 but N/C 0n the TL071 and 81. I think the 10pf cap is just there for stability, I'd guess it will run just fine without it, or it could be wired across the feedback loop instead which may do the same job. Thing to do is wire it up and try it. TL080 is still available from Mouser if all else fails.
2thick4uni
Just had another look at TL080 and 81 datasheet - you don't need to fit the 10pf cap if using the TL071 or 81 as they already have an 18pf cap fitted internally in the same position, whereas it is not included in TL080 and has to be fitted externally. So, the TL081/2 and TL071 or TL072 should work fine and in that case you can omit the 10pf cap from the circuit.
Jackdamery




I got the oscillator part of the circuit working, sans expo converter on +/-9v. I subbed the TL080s for TL071s, the diodes are 1N4148s and the FET is a 2N4393. To get it to work without the expo I connected the input via a 10k resistor to -9V. It was oscillating at a very high frequency.
Jackdamery
Any ideas how I can slow this oscillator down? I've already tried adding larger capacitors.
2thick4uni
A resistor between pin 2 of the op amp (R17A) and ground should do it, or make it a pot to vary the frequency. As I understand it he expo converter sucks current out of the oscillator, the more current removed, the lower the pitch.
bubblesound
this is really fantastic. thanks for posting all of this. and congrats on getting it to oscillate.

on the subject of upgrading chips, i'm going to have to agree with peake. while perfect stability and tracking sounds like a good goal, it's the small variations from VCO to VCO when you've got them playing together that makes the magic. with no drift and perfect tracking it sounds very flat and then you've got the issue of phase between the VCOs. trust me, replacing the 4558s with something really high spec will not help.
there was a trend in the early-mid 90's of replacing output buffers and the expo opamps in vintage synths with tl07x to "clean up" the output and make it stable, etc. what they ended up doing was killing the magic.
Jackdamery
Here's the reset pulse from the comparator:

Jackdamery
Great success! I got the help of my colleague and we found that the comparator was triggering too soon and not discharging the FET for long enough. Changing the capacitor 'C8A' on the comparator from 15pf to 100pf held the FET on for longer and fixed it. I didn't realise that VR1A and R2A on the expo converter are acting as a voltage divider, thus that pot's affect on tune is quite small. removing R2A gave a full sweep. Will post pics a bit later.
Jackdamery






It was run from +/-12v and as you can see from the pics the waveform is 9V peak to peak. Biased from 0-9v, similar to the 10v peak to peak biased from 0-10v on the schematic
Jackdamery
Here's a recording of it. I built up the comparator part too, so it starts off with
square/pulse.

https://soundcloud.com/dot/jupiter-8-vco-built-from
2thick4uni
Well done!

applause applause applause applause
Chok
Good job!
Finally, you changed what components with regard to(compared with) the original plan, can you make a summary?
Jackdamery
Chok wrote:
Good job!
Finally, you changed what components with regard to(compared with) the original plan, can you make a summary?


Hi, of course:

Original -> Mine
Tl080 -> TL071 //Tl081 might be a closer match, as the TL071 is lower noise
CA3046 -> LS318 //Could use a pair of matched 2N3904s
4558 -> 4558
1S2473 -> 1N4148
NF510 -> 2N4393 //Could try 2N3819 as its 5 times cheaper.
2SA1015-GR -> 2N3906

Capacitors:
C8A I changed from 15pf to 100pf to allow the FET enough time to discharge the integrator properly. If using TL080s and NF510s it might not need such a high value.

C7A on the first TL080 is not needed as the TL071 has a bandwidth capacitor internally.

I dropped the CV in resistor from 100k to 40k (R46A)

Trimmers used were Bourns cermet multiturn, although the Jupiter just used one turn trimmers.

Everything else is as per the schematic. Good luck!
Jackdamery
Here's the schematic with modern components.



Parts list:
2 x Tl071 opamp
1 x 4558 opamp
1 x LS318 monolithic NPN pair
1 x 2N4393 FET
1 x 2N3906 PNP
2 x 1N4148 diodes
2 x 10nf ceramic capacitors
1 x 1nf ceramic capacitor
1 x 1000pf polystyrene capacitor
1 x 100pf ceramic capacitor
1 x 100K trimmer
1 x 5K trimmer
1 x 2K trimmer
Assorted metal film and carbon resistors. (metal film designated in schematic with MF).
1 x 1K 3300ppm tempco.
Chok
Ok, thank you very much...
It will be completed for my voiceboard clone of Cs-60 / 80.... It's peanut butter jelly time! nanners
Jackdamery
Chok wrote:
Ok, thank you very much...
It will be completed for my voiceboard clone of Cs-60 / 80.... It's peanut butter jelly time! nanners


No worries. I just had a look at the datasheets for the CA3046 and the LS318.

The CA3046 is apparently VBE matched for ±5mV, is that a maximum of 10mV, or up to 5mV?

The LS318 however is much more closely matched. 0.4mV is typical and 1mv maximum.

This might be too closely matched to keep the authentic JP8 sound. One could match an NPN pair to ~5mV fairly easily, although they wouldn't have the monolothic thermal advantage of the LS318 or CA3046.
elektrouwe
Jackdamery wrote:

C8A I changed from 15pf to 100pf to allow the FET enough time to discharge the integrator properly. If using TL080s and NF510s it might not need such a high value

Jack, did you already measure high frequency tracking of your VCO variant ?
I think R17A is for high frequency tracking. It must be calculated to compensate the (fixed) pulse width of the discharge circuit. If you change C8A, FET & comparator you likely change discharge time. So if you have trouble with high freq. tracking replace R17A by a 470R trimmer and find the new value for R17A.
Chok
The LS318 is almost untraceable, I rather think of choosing 3046 (still available at numerous retailers) or the LM394 which I have already used successfully on my VCO Yusynth,

In the first case, it will be necessary to put back some resistances around the tempco as on the original design, not (sorry, me and English, not simple)...
Jarno
Hope I don't sound like a broken record, but if you don't mind handsoldering tiny smt parts, BCM847bs? Cheap, and matched.
soundmachines
Lm3046 (TI) is in full production and really cheap. You just need a firm hand a good sight as it is a SOIC ! :)
Jackdamery
Chok wrote:
The LS318 is almost untraceable, I rather think of choosing 3046 (still available at numerous retailers) or the LM394 which I have already used successfully on my VCO Yusynth,

In the first case, it will be necessary to put back some resistances around the tempco as on the original design, not (sorry, me and English, not simple)...


Really? I believe the LS318 is still in production. I ordered 2 samples from a local distributor recently in the UK. Their price from them is 3.14 pounds each.

Also as mentioned by 2thick4uni, the 1k 3300 tempco is equivalent to the previous 7000ppm 1k plus the 390 and 3.3k in parallel, thus that is all that is necessary.
Peake
Only matched to 5MV!!! How can anyone possibly make music on something like that! angry angry angry

8_) 8_) 8_)
Jackdamery
I got an email from Littlediode saying they can source NF510 FETs for £4.95 each with a minimum quantiy of 50 pieces, it hardly seems worth it though for the difference in sound it might make.
Jackdamery
Peake wrote:
Only matched to 5MV!!! How can anyone possibly make music on something like that! angry angry angry

8_) 8_) 8_)


I just looked at the LM3046 data sheet and it says 0.45mV is typical but 5mV matching is maximum, so on average they don't perform much worse than the LS318.

Also I emailed Roland asking for some info/names on the development of the Jupiter 8, and received this reply

Quote:
Hi Jack



Thank you for your quick response.



I’m afraid this sort of information is not something that we can provide.



I can confirm that Roland Japan will not release any information of this kind I’m sorry.



Kind regards



Dan

Dan Burton
Customer Support
Roland (UK) Ltd
Office: 01792 702701
Web: www.roland.co.uk
MyRoland
neil.johnson
Not a surprising result unfortunately. Given the Jupiter 8 was designed way back in the late seventies (released in 1981 so likely designed 1979-1980) I would be very surprised if any of the original team were still there in a technical capacity after 30+ years.

Neil
Jackdamery
neil.johnson wrote:
Not a surprising result unfortunately. Given the Jupiter 8 was designed way back in the late seventies (released in 1981 so likely designed 1979-1980) I would be very surprised if any of the original team were still there in a technical capacity after 30+ years.

Neil


True, I thought they might have some stuff in archives etc. It seems more like they don't want to give information than they don't have it though.
Peake
Jackdamery wrote:
Peake wrote:
Only matched to 5MV!!! How can anyone possibly make music on something like that! angry angry angry

8_) 8_) 8_)


I just looked at the LM3046 data sheet and it says 0.45mV is typical but 5mV matching is maximum, so on average they don't perform much worse than the LS318.


Interesting; I'd never seen an "average" measurement for one. Far better than I'd expected.

Note that they are readily available in the US for $0.49 each:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G32158
Nordcore
I guess the main difference between LS318 and CA3046 in a log circuit is not due to the UBE match but to the lower RBE of the LS318.
Thus the LS318 does the log-function a lot better. (Better HF tracking)
Jackdamery
Nordcore wrote:
I guess the main difference between LS318 and CA3046 in a log circuit is not due to the UBE match but to the lower RBE of the LS318.
Thus the LS318 does the log-function a lot better. (Better HF tracking)


Hmm, interesting. Any ideas why Roland chose to use a 3046 in this circuit rather than just a monolithic pair? It leaves 3 of the transistors unused and takes up a lot more space.

Edit

I'm wrong in this. It uses 4 of the 5 transistors on each chip.
oldcrow
2thick4uni wrote:
I think I'd replace the 4558 with a dual precision op amp such as LT1013, won't affect the sound at all but will reduce drift in the summer and expo converter. Likewise replace the 3046 with LS318 or similar or even match a pair of BC547's or similar. The transistors in the 3046 are only matched to about 3mv, you can hand match transistors closer than this. Any 1k 3300ppm or 3500ppm ptc tempco should be fine. Multi turn cermet trimmers will be ok too. I'm sure there will be a few fet's that will work ok, best way is to model the circuit in Ltspice and see what works.


This is what I did for the crOwBX VCOs. The J112 FET works fine in place of the 2N4302, would probably do the same here. Of course, you now need the LS318 in the SOIC-8 or TO-78 (can) package as they no longer sell the PDIP version. angry
Jackdamery
oldcrow wrote:


This is what I did for the crOwBX VCOs. The J112 FET works fine in place of the 2N4302, would probably do the same here. Of course, you now need the LS318 in the SOIC-8 or TO-78 (can) package as they no longer sell the PDIP version. angry


Wow that's cool, I was completely unaware of this. So you already did the same kind of thing with an OBX?

I was perusing the service manual today and noticed that it said the TL080 and TL082s were selected by slew rate. Presumably those with a faster slew.
2thick4uni
Hiya Jack,

I've just done a simulation of the circuit in LTSpice, the oscillator is running way too fast, as you found. I changed C8a from 15p to 15n and it is running nearer the speed it should, with 0volts in I'm getting just under 1khz - much better than the 30khz or more with it at original value but still a bit on the high side. The only other component that varies the oscillator speed is R18a, but I needed to take this up to 680k with C8a at 15pf to get the same result.

Anyone out there want to take their JP8 apart and let us know these actual component values in the VCO??? very frustrating

The expo converter works fine and everything is as expected there.

I've tried many different nfet transistors for and all of them seem to work ok, very little difference between them.

If someone can pm me to let me know how to upload pix I'll put up some pix of the sim running.




.
Nordcore
I haven't done exactly *this* circuit - but from experience with similar cicuits I guess it does work well with the shown component values.
At 0 Volt input the current in the 1nF integrator capacitor is 15V/470k= 32µA[1].
The comparator voltage is 11.5V, so it takes 360µs[2] to charge the capacitor to the comparator switch voltage, giving 2.7kHz.
(... the reset time is (guessed...) around some µs and ignored. Adjust the 15pf to give a pulse long enough to discharge C6A completely. Can be seen on the scope w/o problems. )


[1] Pin 11 (CA3046) is regulated to zero volts. So the current in Pin 11 is exactly 15V/470k. Pin 6 is zero volts, Pin 9 is zero volts (because input=0V). Because both transistors are matched, and they have the same base-emitter voltage, their collector current must be the same. So the current to C8a is the same as what goes through R9a.

[2] C=Q/U, Q=It => C=It/U. Its that dead simple because the collector of the transistor is a good current source - so current keeps constant and we don't have to do integrals. (As long as R17A is ignored=set to zero )
minisystem
2thick4uni wrote:
Hiya Jack,

I've just done a simulation of the circuit in LTSpice, the oscillator is running way too fast, as you found. I changed C8a from 15p to 15n and it is running nearer the speed it should, with 0volts in I'm getting just under 1khz - much better than the 30khz or more with it at original value but still a bit on the high side. The only other component that varies the oscillator speed is R18a, but I needed to take this up to 680k with C8a at 15pf to get the same result.

Anyone out there want to take their JP8 apart and let us know these actual component values in the VCO??? very frustrating

The expo converter works fine and everything is as expected there.

I've tried many different nfet transistors for and all of them seem to work ok, very little difference between them.

If someone can pm me to let me know how to upload pix I'll put up some pix of the sim running.


.


Any chance you'd be willing to zip and share the LTSpice project and models you used? I've successfully simulated filters, but have not had any luck with VCOs in LTSpice (lock up or won't oscillate). I find LTSpice is a great learning tool, but I've hit a wall when it comes to VCO design.

Back on topic: fascinating study Jack! I picked up 10 LS318s a few months ago, but they were bloody hard to get hold of. I built a discrete version of the Hearn Morley VCO using the LS318 and another version using the BCM847. Both worked and sounded great but the LS318 version definitely tracked better. I suppose this was due to the better log conformance of the 318? In the case of the JP8, I guess the auto-tune algorithm takes care of any non-ideal tracking.
Jackdamery
2thick4uni wrote:
Hiya Jack,

I've just done a simulation of the circuit in LTSpice, the oscillator is running way too fast, as you found. I changed C8a from 15p to 15n and it is running nearer the speed it should, with 0volts in I'm getting just under 1khz - much better than the 30khz or more with it at original value but still a bit on the high side. The only other component that varies the oscillator speed is R18a, but I needed to take this up to 680k with C8a at 15pf to get the same result.

Anyone out there want to take their JP8 apart and let us know these actual component values in the VCO??? very frustrating

The expo converter works fine and everything is as expected there.

I've tried many different nfet transistors for and all of them seem to work ok, very little difference between them.

If someone can pm me to let me know how to upload pix I'll put up some pix of the sim running.

.


Nice one. I got it working fine with C8A as 100pf, did you build the expo part as well?

I moaned at everyone on Gearslutz and they'ved provided me some really high res photos of the VCO module board, unfortunately top down so you cant read cap or transistor values, but still:
Gearslutz JP8 photos

.
Jackdamery
minisystem wrote:

Back on topic: fascinating study Jack! I picked up 10 LS318s a few months ago, but they were bloody hard to get hold of. I built a discrete version of the Hearn Morley VCO using the LS318 and another version using the BCM847. Both worked and sounded great but the LS318 version definitely tracked better. I suppose this was due to the better log conformance of the 318? In the case of the JP8, I guess the auto-tune algorithm takes care of any non-ideal tracking.


Thank you! So that was you that built the HMVCO. Is it similar? I have a couple of HM chips and they sound a track similarly to the JP8 one I built.

Did you use the DIP8 LS318s? I got the TO-71 metal can ones as free samples from a distributor in the UK. £3.40 each was the quote. Orders subject to minimum order value £50.00.
2thick4uni
[/img]
Nordcore wrote:
I haven't done exactly *this* circuit - but from experience with similar cicuits I guess it does work well with the shown component values.
At 0 Volt input the current in the 1nF integrator capacitor is 15V/470k= 32µA[1].
The comparator voltage is 11.5V, so it takes 360µs[2] to charge the capacitor to the comparator switch voltage, giving 2.7kHz.
(... the reset time is (guessed...) around some µs and ignored. Adjust the 15pf to give a pulse long enough to discharge C6A completely. Can be seen on the scope w/o problems. )


[1] Pin 11 (CA3046) is regulated to zero volts. So the current in Pin 11 is exactly 15V/470k. Pin 6 is zero volts, Pin 9 is zero volts (because input=0V). Because both transistors are matched, and they have the same base-emitter voltage, their collector current must be the same. So the current to C8a is the same as what goes through R9a.

[2] C=Q/U, Q=It => C=It/U. Its that dead simple because the collector of the transistor is a good current source - so current keeps constant and we don't have to do integrals. (As long as R17A is ignored=set to zero )



Many thanks Nordcore, very helpful indeedl!

I have got to the root of the problem so the sim now works correctly. The slew rate of IC4a was causing the problem. I modeled it with LT devices, I used the LT1013 instead of TL080, I didn't realise it had a much poorer slew rate. It's a better op amp but a poorer comparator d'oh!

So, I tried the LT1057 instead, it has similar slew rate to TL080. With that in circuit I can get C8a down to 220pf and everything runs ok. If I replace it with a comparator instead (I used the LT1017) then it runs fine with C8a at the documented value of 15pf. Could be that Roland had to select TL080's for fastest slew rate. I'm sure that Roland will be relieved to hear that the VCO does actually work! hihi

BTW at zero volts in it shows about 350mv at output of the summing opamp (pin7), this is because of the bias voltage applied by R1a and R5a, if I take these out of circuit it gives 0v at pin 7. With these in circuit it needs about 1.78v in for zero volts to expo convertor. I think that R5a could be for high end tracking?

I've included pix of sim and also zip file containing LTspice files for anyone else interested in further exploration!

2thick4uni
minisystem wrote:


Any chance you'd be willing to zip and share the LTSpice project and models you used? I've successfully simulated filters, but have not had any luck with VCOs in LTSpice (lock up or won't oscillate). I find LTSpice is a great learning tool, but I've hit a wall when it comes to VCO design.


Yep, no problem. Zipped files attached. Pretty sure all of the components are in standard LTspice library so should run without importing any extra component models.

Have fun!
Jackdamery
2thick4uni wrote:
Could be that Roland had to select TL080's for fastest slew rate. I'm sure that Roland will be relieved to hear that the VCO does actually work! hihi



Yeh if you look at page 13 of the service manual on the top right it mentions TL080s and TL082s are selected on slew rate, presumably the fastest.
neil.johnson
A good reference implementation of this kind of oscillator is the ASM-1 VCO.

Oh, and what you amusingly refer to as the "breakdown diode" is nothing more than converting the output of the op-amp-as-comparator into an open-collector output (see ASM-1 VCO use of LM311 comparator), only pulling the gate of the JFET to ground - you don't want the gate going any higher than one diode drop above the D-S terminals or the reverse-bias gate diode will start to conduct.

Neil
Jackdamery
neil.johnson wrote:
A good reference implementation of this kind of oscillator is the ASM-1 VCO.

Oh, and what you amusingly refer to as the "breakdown diode" is nothing more than converting the output of the op-amp-as-comparator into an open-collector output (see ASM-1 VCO use of LM311 comparator), only pulling the gate of the JFET to ground - you don't want the gate going any higher than one diode drop above the D-S terminals or the reverse-bias gate diode will start to conduct.

Neil


Ok, so whats the other diode doing?
neil.johnson
Jackdamery wrote:
neil.johnson wrote:
A good reference implementation of this kind of oscillator is the ASM-1 VCO.

Oh, and what you amusingly refer to as the "breakdown diode" is nothing more than converting the output of the op-amp-as-comparator into an open-collector output (see ASM-1 VCO use of LM311 comparator), only pulling the gate of the JFET to ground - you don't want the gate going any higher than one diode drop above the D-S terminals or the reverse-bias gate diode will start to conduct.

Neil


Ok, so whats the other diode doing?

The one strapped across the output of the integrator op-amp? At a guess I would say clamping that pin to no more than one diode below GND to protect the circuit against start-up conditions when power is applied (op-amps can do funny things while their power rails are coming up, including weird stuff on their outputs).

Neil
minisystem
2thick4uni wrote:
minisystem wrote:


Any chance you'd be willing to zip and share the LTSpice project and models you used? I've successfully simulated filters, but have not had any luck with VCOs in LTSpice (lock up or won't oscillate). I find LTSpice is a great learning tool, but I've hit a wall when it comes to VCO design.


Yep, no problem. Zipped files attached. Pretty sure all of the components are in standard LTspice library so should run without importing any extra component models.

Have fun!


Excellent. Thanks. Having fun now. thumbs up
Jackdamery
Okay so I built up the VCA section of the Jupiter using an LM13700 instead of the BA662s. I added a second DAC to the Arduino and used it to send a CV to the VCA with control only over decay from a pot into the arduino.

So the topology now is:

Farfisa keybed -> Arduino -> DAC for VCO CV & DAC for VCA CV -> Jupiter 8 VCO Saw/Triangle and Jupiter 8 VCA.

[s]http://soundcloud.com/dot/jupiter-8-homebuilt-vca[/s]
minisystem
Jackdamery wrote:
minisystem wrote:

Back on topic: fascinating study Jack! I picked up 10 LS318s a few months ago, but they were bloody hard to get hold of. I built a discrete version of the Hearn Morley VCO using the LS318 and another version using the BCM847. Both worked and sounded great but the LS318 version definitely tracked better. I suppose this was due to the better log conformance of the 318? In the case of the JP8, I guess the auto-tune algorithm takes care of any non-ideal tracking.


Thank you! So that was you that built the HMVCO. Is it similar? I have a couple of HM chips and they sound a track similarly to the JP8 one I built.

Did you use the DIP8 LS318s? I got the TO-71 metal can ones as free samples from a distributor in the UK. £3.40 each was the quote. Orders subject to minimum order value £50.00.



I've got a couple of Hearn Morley VCO chips but I've yet to get around to testing one. I used the SOIC8 LS318 (I used an SMT design as I wanted it as small as possible to keep PCB costs down). I got 10 from Trendsetter electronics but shipping to Canada was astronomical so I had them couriered to a cousin in NYC. Certainly not as easy as Digikey. They were about $4.50 USD each. In another version I used the BCM847 matched pair. At 1/10th the price and readily available, I plan to stick with the BCM847.

Looking forward to seeing how this develops! smile
Jackdamery
I received four TO-18 NF510 FETs from the US today. They have the old style National Semiconductor logo on them. I'm wondering if they are any different to the TO-92 NF510s from the photos of the Jupiter Module board?
filterstein
Would it be inpolite if i asked were you got them from?
Would like to see if they sound different for the system 700 vco clone.
Jackdamery
filterstein wrote:
Would it be inpolite if i asked were you got them from?
Would like to see if they sound different for the system 700 vco clone.


Not at all. They were pulls from apparently working test equipment advertised on ebay.

Here's the auction

How many are used in the system 700 vco?
filterstein
Ah, luck in auction.
I hoped you'd found a more regular source.

There is one for each vco module.
Many early rolands use the ua726/nf510 combination.
Jupiter 8 is different in that others use 2sk30 in designs that are not based on the ua726.
Jackdamery
filterstein wrote:
Ah, luck in auction.
I hoped you'd found a more regular source.

There is one for each vco module.
Many early rolands use the ua726/nf510 combination.
Jupiter 8 is different in that others use 2sk30 in designs that are not based on the ua726.


Well I just messaged him asking what piece of equipment he pulled them from. Once I've done some IDss, Gs, etc tests I can probably send you one to test with. Where are you based?
Jackdamery
Ok so ran some tests and suprise, suprise, the TL080 showed no difference in amplitude or frequency from the TL071 in the comparator section. The only difference is the TL080 worked fine without the C8A flyback capacitor and showed no difference between 15pf and 100pf.

In the integrator there was no difference in amplitude or frequency between the TL080 and the TL071, the TL080 needed the 10pf compensation capacitor as specified, otherwise it went into super-sonic frequencies.

There was no measurable difference between the NF510 and the 2N4393 either.

Regarding the NF510 pulls I bought on ebay the guy came back saying.

Quote:
I'm not positive but I think it was a Hewlett packard function generator. I've already scrapped it for the gold.


Jarno
Gold? The gold plating on cardedges and connectors, really?
Jackdamery
Jarno wrote:
Gold? The gold plating on cardedges and connectors, really?


Well according to some ex-BT coworkers, there aren't many old mechanical telephone exchanges left because the silver in the relays is worth more than the units.
negativspace
Is that red paint on your cutting board, or was this transistor removed from the still-beating heart of some unfortunate beast?
Jackdamery
negativspace wrote:
Is that red paint on your cutting board, or was this transistor removed from the still-beating heart of some unfortunate beast?


Lol, it's red paint I spilled aged 12, which is half my life ago cry
Jackdamery
[s]http://soundcloud.com/dot/ir3109-jupiter-filter-made[/s]

I cannibalised a Boss PH-2 for the two IR3109s today and built up the filter circuit minus the resonance part.

Sorry for the lack of tunefulness. Don't have enough pins on the Arduino to fully scan the keyboard and I'm lazy to figure out how to mux it.
neil.johnson
Jarno wrote:
Gold? The gold plating on cardedges and connectors, really?
HP used to (not sure if they still do) gold plate across the entire PCB not just edge connectors. For example:

http://mightyohm.com/blog/2009/11/test-equipment-pr0n-the-hp-3312a/

So it is very likely that there's quite a bit of gold in them thar HPs!

Neil
Jarno
Indeed!
"They don't make them like they used to"
Jackdamery
I've built the breadboard design onto a 'PCB' using Adafruits 'perma-proto' board, which allows you to pretty much solder up your breadboard designs without even thinking as it's layout matches breadboard.

I used break-off socket strip for some connections so the integrator and comparator capacitors and the FET are hot swappable. This should allow some flexibility even in a permanent board.


Jackdamery
Hey guys,

any idea what this capacitor type/value is. On the schematic it's listed as .47/50 BP. I'm guessing BP stands for bipolar, but I thought electrolytics were polarised not bipolar. At any rate the cap looks like an electrolytic from a photo of the module board I have, and the silkscreen of the module board would seem to confirm the one in the photo is indeed C44.

Also are the green blobs in the photos Mylar caps?

neil.johnson
0.47uF 50V. And yes, some electrolytics are bipolar.
The green caps are most likely Mylar (which is just a trade name for a cheap polyeter).

Neil
raisinbag
Ya I was gona say bipolar as well. Ray at MFOS uses than in his stuff. I have never used one but have out normal electros back to back, like attaching the neg leads together and soldering in the pos leads.
2thick4uni
They probably fitted this cap to save space on the pcb, a 470n cap used to be pretty big so using a 0.47uf bipolar electro made sense because of its smaller size on a tightly packed pcb. Caps have got much smaller over the years, it would be fine to replace it with a 470nf film cap, they are usually rated at higher than 50v so no problems there.

If it's in the audio path then film cap would be a better choice than an electro cap too.
Jackdamery
I was looking at this x0xb0x build :http://www.bivvend.co.uk/xox/ and noticed the trimmers were the same as the ones(VR1, VR2, VR3) from the JP8 expo converter, checking the x0xb0x BOM showed that these are Vishay CT6EPxxx series ~10% tolerance trimmers, which may have been discontinued I'm not sure. Also of note is they take a phillips instead of a flathead screwdriver as the original. I'm also wondering if the letter to the right on the top of the trimmer has any significance.

EDIT:
Digikey has them albeit manufactured by Copal electronics, not Vishay:
100k
2K
5K

Datasheet


I know you could use the Bourn's 3363 series just the same, it's just interesting to find out.

Jackdamery
They have Roland stock numbers: 13299550 13299549 13299552
and are referred to as ET-6P series in the service manual BOM. Sounds a little similar to CT6EPxxx.
emuarc
Hi folks, I have replicated the Jupiter 8 LFO, details are here

http://www.amsynths.co.uk/blog/

it is part of a project to build a complete Dual VCO.

Jackdamery
emuarc wrote:
Hi folks, I have replicated the Jupiter 8 LFO, details are here

http://www.amsynths.co.uk/blog/

it is part of a project to build a complete Dual VCO.



Interesting. Will it be in something more normalised and powerful, instead of a static module?
Chok
[quote="Jackdamery"]Here's the schematic with modern components.




Hello All

I have a small question:

The Jupiter 8 vco use two supply voltage: +/- 15V and +/-13V. In this schematic, do you use two power supply or just one (13 or 15v) ?

Thxs
E.A.S.
[quote="Chok"]
Jackdamery wrote:
Here's the schematic with modern components.




Hello All

I have a small question:

The Jupiter 8 vco use two supply voltage: +/- 15V and +/-13V. In this schematic, do you use two power supply or just one (13 or 15v) ?

Thxs


Hi Chok,

The +-13v you see on the top right of this schematic page refers to the voltage levels of the reset pulse. in fact the line drawing next to the +-13v is a drawing of the pulse shape.

-Mike

[EDIT] looking at the full page this schematic piece this comes from, I see there IS +-13v ref. power supply.
Chok
Ok Mike

But in the service manual, only the last AOP (TL071 top right) is supplied with +/-15V. Other AOP are supplied in +/- 13v (with a local little power supply)...

I go to test with +/-13V PSU and other test with +/-15V
E.A.S.
Chok wrote:
Ok Mike

But in the service manual, only the last AOP (TL071 top right) is supplied with +/-15V. Other AOP are supplied in +/- 13v (with a local little power supply)...

I go to test with +/-13V PSU and other test with +/-15V



That is correct.

+-13v ref. Page 11 top right, of the Service Manual.

-M
Chok
Hi
I realized the VCO which works straight off. On the other hand, I cannot come down below 650 Hz, what is 10 times too much with regard to the normal, no?
An idea of the source of the problem?
Nordcore
Adjust you input voltage so you get 0 Volts at pin 9 of the CA3046.
(=Output of the pitch CV summing amp is at zero Volts. )

Current in your 1nF VCO cap is than 13V/470k=28uA.
Charging to 10V requires (C=Q/U; Q=I*t) t=C*U/I = 1nF*10V/28uA=0.36ms (period time) that gives 2800Hz.

If that matches, than the VCO part is OK. (And any range problems are just on the input side of the summing amp. )
Chok
My version is the one of Jackdamery. I use a LM394 for the pair of transistors, I fed all the circuit (including the TL071 to the right) + /-13V...
I am going to verify my PCB and components once again to see if there is no error...

Thanks for your help applause
donepe
im replacing the TSP102 tempco resistor on one of the module boards of my Roland Jupiter 8

i ordered an exact replacement from little diode in the UK

the problem is that the TSP102J they sent seems to be encased in a TO-92 transistor case.


im wondering how i can do this as this replacement doesn't have the flat connection I need to properly rest with thermal paste on the 3046 IC

any tips would be appreciated

[img][/img]
guest
according to the littlediode website, that is a thyristor, not a thermistor. i dont think it will work.
donepe
do you know where i could source a correct part?


I thought this was the proper replacement
guest
was there another thread on this recently? i seem to recall some discussion a month back or so. if you have info on the resistance value and tempco, i could look around. i have no ideas on an exact replacement, though.
guest
how many pins does the part have? its a bit hard to tell from the picture, the third "pin" in the middle might just be a shadow? if it only has 2 pins, then it might be the right thing. measure the resistance between those 2 pins, and if its 1k you might be fine (best to check both directions - flip the probes to make sure it conducts equally in both directions). if thats the case, then leave the leads long, and just bend the whole part over so the case rests against the top of the IC.
donepe
yes it has 2 pins and the proper specs its just the T092 casing that is different

I'm going to install and give it a try today
guest
awesome! sorry to have said otherwise - i looked up the part at littlediode and they said it was a thyristor.
donepe
I'm still a bit concerned because of the case, the original cap has a metal flap that rests on the IC. maybe it grounds it?

I'm not sure if it will make a difference but will find out soon enough
guest
the metal flap is probably a heat sink, to get better thermal conduction to the die. it helps, but i suspect it wont make that much difference, considering the heat alredy has to go through the plastic case of the DIP package.
donepe
success!

after replacing with this TSP102J, i put a touch of thermal paste on the 3046 IC
then mounted the casing to it

the module board now works perfectly and my Jupiter 8 is back!

thanks for your help
tinkerdude
A dual transistor which is similar (the single parts) to general purpose ones like 2n3904 or BC547, only available as SMT, is the
BC847BS, available e.g. at RS-online for less than 10 cents IIRC.
The PNP complementary would be BC857BS I think.

Those are used in the Arturia MiniBrute, btw.

Ant then, as one mentioned, the LM3046 is still being made and can be pretty cheap, especially the SOIC variant.
BurnettX360
I've built both the VCO and the Expo Converter, and while the VCO does what it has to do and the Expo Converter gives me a full sweep when removing R2A I cannot get the 1V/oct to do what it has to do.

Putting 1V increments on the 100k 1v/oct input doesn't scale exponential as it seems.

I've tried the calibration technique from the Roland technotes, but after setting te base frequency I cannot use the width and linearity to tune. Since there is actually no change in frequency when i change vr2a en vr3a.

Can someone help me?
guest
does the output do anything when you apply a voltage to the v/oct input? is it stuck at either the max or min frequency?
BurnettX360
Yes absolutely! When I increase the voltage on the V/Oct input the output increases as well. Just not exponential as you would expect.
Turning VR1a also gives me a nice broad sweep between a Hz and more than 15KHz.

So VR1a gives full sweep. VR2a and VR3a has little effect on the frequency no matter how much input voltage I apply (I only tried 0-5V btw.).
guest
measure the voltage across R14 for a CV input of 0V and a CV input of 10V. it should go from -100mV to +100mV (or somewhere around there). it should also be linear, so at 0V CV you shoud get 0V across R14.

check R5A for correct value. perhaps just remove it and see if it changes the behaviour any.
BurnettX360
Thanks guest,
I've reworked the Expo converter on my breadboard. Since the voltage across R14 wasn't any near the range you've specified.

Also I wasn't aware that the CV should go from -10 to +10V. I really thought the CV went from 0V to 5V. But I tried with -5V to +5V from my arduino board which gave me for -5V approx. -100mV. 0V gave me approx. 0mV and +5V gave me around +820mV. Looks pretty linear to me indeed.

But keeps the difficult part for me how to tune this thing :( I only have an arduino board present to generate my CV input with an R/2R DAC where I have created an array which creates the voltages from 0..5V with approx. 83.3mV increments. Is it possible to tune only with the positive voltages present or is there another way I can generate the whole -10V to +10V (somehow).

Thanks again for your help. I will be posting samples from my first encounters soon smile
guest
BurnettX360 wrote:

Also I wasn't aware that the CV should go from -10 to +10V. I really thought the CV went from 0V to 5V. But I tried with -5V to +5V from my arduino board which gave me for -5V approx. -100mV. 0V gave me approx. 0mV and +5V gave me around +820mV. Looks pretty linear to me indeed.


CV should go from 0V to 10V (or less, depending upon how many octaves you want), not -10V to +10V. this CV should drive the base of the differential pair at 18mV/octave. so 0V to 10V is 180mV of range, which is best distributed as -90mV to +90mV. is your +820mV listed above a typo? is that actually 82mV? the output needs to be exactly linear, as 1mV is 150cents. since this is not the case, remove R5A and see what you get.
BurnettX360
I must have been tired when I read your post :(
So now new measurement:
With R5A in place:
0V CV in: -87.5mV
5V CV in: 0V
10V CV in: 90.3mV

I can adjust the range with VR1A, VR2A and VR3A. So if I understand you correctly. When I'm somehow able to get the 0-10V CV in to provide the -100mV to 100mV over R14 I have the oscillator in tune? Or is that step 2?

with R5A removed:
0V CV in: -78mV
5V CV in: 10.3mV
10V CV in: 100mV

And again I can adjust VR1A, VR2A and VR3A to change the values measured over R14.

So how do I manage to get the CV to respond linear?
guest
ok, that all seems good. try tuning it again with R5A removed. apply 1V CV, measure the frequency, and then apply 2V CV and measure the frequency. adjust VR2A to make the frequency at 2V twice that of the frequency at 1V. you have to keep going back and forth between 1V and 2V when you do this, as the frequency for both changes as you turn VR2A. once you have that set, then check the frequency at 1V increments to see if the frequency is doubling each time. it should be pretty stable from 0V to 5V, and then might have some trouble after that.
BurnettX360
Hi Guest,

I'm actually quite new on this matter and I really appreciate you helping me out on my encounters to get this right! So there we go: I cannot get the frequency to double while juggling VR1A and VR2A.

When I apply 1V and I set via VR1A the course frequency on 65.4Hz that works fine.
Next when I apply 2V the frequency goes up to 95Hz (VR2A in the lowest position), so I adjust VR2A to get 130.8Hz. No problem. The VR2A goes almost to it's max position to get the 130.8Hz but still.

Now it doesn't make sense to me anymore. I go back to applying 1V. Now that frequency has also changed (which I get) to 93Hz. adjusting VR2A back so that it reads 65.4Hz fixes nothing since I have to crank it up again when applying 2V to get to 130.8Hz.

So I am assuming I should now use VR1A to set the frequency back to 65.4Hz. which I now did. And next go back to applying 2V. My frequency is now 92Hz with almost no reserve on VR2A to crank it up to 130.8Hz.

So obviously I'm doing something wrong here or there is still an error in my breadboard setup.

Another thing: when I remove R5A should I bridge it with a jumper wire or just leave it disconnected (which results in VR3A doing nothing at all - at least it seams to me that way).
guest
do not jumper R5A.

can you take measurements and report back what the frequencies are for 0V, 1V, 2V, 3V, 4V, and 5V CV? also, measure the input to the circuit to make sure the CV is what you think it is (as i recall you are generating it with an arduino?). the important thing is that there is exactly 1V difference between these steps (within a few millivolts). keep the trimmers in the same position for all measurements. if the ratio of the frequencies is constant, then you will just need to increase the gain on the input stage. if they are not, then there is an issue with the charge/reset circuit.

what opamps are you using?
BurnettX360
What i did with the arduino was create a r/2r resistor ladder with 100k and 200k resistors and send the output to the cv input of the oscillator.

The weird thing is that when I apply the 4.9V from the resistor ladder I get 297Hz, but when I put the 4.9V directly from the 5V output of the Arduino I get 1736KHz. I guess the CV generated by the Arduino is no good then?

0V 50 Hz
0.994V 72 Hz
2.017V 105 Hz
3.032V 152 Hz
4.03V 218 Hz
4.9V 297 Hz

I have used RC4558IP and CA3046 in the Expo Converter and 2 TL080 in the Oscillator. The JFET is a2N4393.
guest
ok, that makes a lot of sense. the output resistance of your R/2R ladder is adding with the input resistance of your CV buffer stage, and you are getting only half of your gain you expected. there are 2 options here: 1. put a buffer amp after your R/2R ladder, or get rid of the input resistor. the output of an R/2R ladder is the same regardless of the voltage it is sending, so the latter option would be fine if you only intend to use the arduino connected to it. otherwise you will need option 1.

another thing to note, is that the arduino is not producing a very linear output. the step sizes are 0.994, 1.023, 1.015, 0.998, 0.897. the resistors need to be very closely matched to have this work right.
BurnettX360
Thanks a lot for helping me out on this. As i mentioned earlier, I'm all new to this, but am more than willing to learn!

My ultimate goal is to build something like tiergrinder did. And have a functional synth. But study first smile unfortunately Imhave no device that can generate a decent CV/gate at the moment so I have to settle with the arduino. Perhaps I'm better of buying some MIDI to CV module or something smile

Now I'm off to bed, but tomorrow I will get rid of the 100k input resistor and check the results. Thanks again for helping me out! I might need you for the BA662 clone as well in time hihi
guest
the arduino should be fine, you just need better matched resistors. you can either measure them and find a bunch that are close, or buy some 1% (or 0.1%) resistors. 1% isnt technically a tight enough tolerance, but typically they will be better matched than that, so it will work anyways.

notice how the frequency doubles every 2V in your sequence, that just means the gain is off, so fixing the R/2R issue should make it work just fine.
BurnettX360
hi guest,

Sorry for the delay in responding, but we have some +25 degrees C temperatures here, so to spend my time on the attic with +30 didn't seem to be a good idea smile.

But.... I've managed to get it working. I used 1% resistors, hand matches as close to one another as possible, all within .5% (lowest to highest

My Arduino CV generates now a nice and steady 1.000V, 2.000V, 3.000V and 4.000V. Next as you said I removed the 100K from the CV input as I'm currently not educated enough to build the buffer in the arduino circuit. I cannot get the full 0-5V through the Opamp. I've tried using the 4558 as a voltage follower.

And the result is a VCO that scales nice (and allmost in tune!) I've put another VCO to work and put an Arduino arpeggio on top and I am pretty pleased!

Thanks a lot for your help. It means a lot to me because I learn a lot the last weeks. I'll try uploading a soundsample shortly.
guest
awesome! glad to hear you got it working.
BurnettX360
Now I managed to get the voltage follower/buffer to work on the Arduino. I used an MCP602 Linear OpAmp. Now I'm able to drive both VCO's with one CV-out on my Arduino. Resulting in this arpeggio w00t (quite proud) w00t

[soundcloud url="https://api.soundcloud.com/tracks/263458130" params="auto_play=false&hide_related=false&show_comments=true&show_use r=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]
BurnettX360
And a picture of my breadboarded VCO's, Powersupply and Arduino R/2R resistor ladder (with non functional opamp).

[/img]
dikkietrom
BurnettX360 wrote:
Thanks a lot for helping me out on this. As i mentioned earlier, I'm all new to this, but am more than willing to learn!

My ultimate goal is to build something like tiergrinder did. And have a functional synth. But study first smile unfortunately Imhave no device that can generate a decent CV/gate at the moment so I have to settle with the arduino. Perhaps I'm better of buying some MIDI to CV module or something smile

Now I'm off to bed, but tomorrow I will get rid of the 100k input resistor and check the results. Thanks again for helping me out! I might need you for the BA662 clone as well in time hihi


Check out the ad5372 eval board. It comes with software for 32 dac channels. I have made more convenient software or have arduino code for you to control it in your own way if you like. You can read more in my construction report here on the forum https://www.muffwiggler.com/forum/viewtopic.php?t=170006&start=0&postd ays=0&postorder=asc&highlight=

I am also going to use it as power supply for the vco, need power transistors to provide the current. I will show when I get to it

I am going to try to develop this vco in the automated matrix, thanks for all the hard work and all the info. It makes my plans much more easy to realize or just plain realizable

Oops only now I see it is you oops
BurnettX360
Maybe a stupid question, but how do I hand pick TL080's on slew rate? I'm planning on picking up om the JP8. Any help is truly appreciated.
dikkietrom
Is it about the same rate for all or the fastest rate ?

Here is explained how to calculate


http://www.radio-electronics.com/info/circuits/opamp_basics/operationa l-amplifier-slew-rate.php
BurnettX360
Well the engineer notes of the Jupiter 8 state that the Tl080 are selected for the fastest slew rate. Since all the tl080 in the same series have the same specs on paper, you should somehow select them on how they perform instead of using the calculations. How can you measure/ select them based on fastest slew rate with minimum effort?
indigoid
Is there some other reason to use TL080 instead of TL071? Slew rate specs are about the same at 13V/µs... I assume it wasn't the only requirement here

I guess you'd feed candidate opamps a square wave and measure the transition times?
BurnettX360
I'm kind of learning all this as i go, so if anyone can tell me how i do this. That would be really great! Thanks
guest
there are a couple of ways of going about it. one is to just try all the opamps you have, and listen to the difference. what youll be listening for is pitch tracking in the upper octaves. the other way is to build a little comparator circuit on a breadboard, hook up a function generator with a square wave to the input, and look at the output on an oscilloscope. the time it takes for the scope trace to go from full low to full high is the slew time, and you want this as short as possible.

personally, i dont think it will make much difference either way.
indigoid
guest wrote:
personally, i dont think it will make much difference either way.


at a datasheet slew rate of 13V/µsec, how could it?

at 30Vpp it should take ~2.3µsec to slew from one peak to the other

so it should be able to handle at least ~217kHz, way beyond what is theoretically required even for a very very narrow pulse width

I would certainly like to know why Roland made those engineering notes. Is my math wrong?
guest
its mostly about the reset pulse. it can assuredly keep up with the slope part of any sawtooth wave it wants to make. it is used in two ways, one as the integrator, and another as a comparator. the comparator needs to respond fast to the integrator reaching its threshold, and part of this is the slew rate. lets say it takes a microsecond to slew enough to activate the reset switch, then thats another microsecond added to the total period of the waveform. same with the reset on the integrator itself. it might take a microsecond to slew back down to 0V. 2us doesnt sound like a whole lot, but up at 10kHz, a period is 100us, so thats 2% drift in frequency. a resistor is sometimes placed in series with the integration cap to reduce the total charge required to reach the threshold, thus compensating for this finite switching time with an offset that increases with charging current (and thus frequency).
dikkietrom
ah good to see it is going on here. I see the notes now too but not specifically about any speed. How can I measure on my original boards here without harming them? I am willing to do anything as long as the risk is minimized that I am going to feel really stupid hihi
guest
if your opamps are socketed, you can swap them out and measure the reset pulse time at the outputs with an oscilloscope.
dikkietrom
guest wrote:
if your opamps are socketed, you can swap them out and measure the reset pulse time at the outputs with an oscilloscope.


Ok I can do that but I need step by step clear instructions cause I need to be secure about it that I am doing it right and also not destroy anything. It is probably important, maybe key to getting the sound right?

Not socketed btw but there should still be a way. I can use little ic clips. I am willing to buy these even for this quest, no problem as long as I am operating safely. Willing to learn anything always!

Btw I am about to order a bunch of your ba662 clones, I see your signature just now SlayerBadger!

Cant you do the same with ir3r01 or how much would reverse engineer ic service in china cost to do this. i asked quotes but got no decent reply yet. i have absolutely no clue, is it hundreds , thousands , tens of thousands?
guest
if you want to test them in the circuit, you could unsolder and resolder every one you tested, but that sounds like a pain. i might start by measuring the ones that are in there originally, and seeing how they compare to the replacement one you put in. if they are close, then figure its good enough.

to test it, take a look at the sawtooth output on an oscilloscope. measure the time it takes for the ramp to reset. should be around 1us or so.

it should be possible to clone the IR3R01, but the difficult part is making it as small as the original. there isnt much to an OTA, so the BA662 is easy to do, not so much for other chips. and the sales of a few hundred, or even a few thousand of them, is not worth the time of any chip fab.
Kirill
Hello to all Wigglers!
I'm new to here smile
First I want to say "Big Thanks!" to all engineers and hobbyists who are making such great efforts to let DIY synth. knowledge to be much easier to get and understand!
I'm mostly a musician and a composer. So this part of the music making world is very new for me.

Few months ago I've started to create the VCO of this type but the oscillator part differs.
1st I want to add that the schematic runs on two 9v batteries.

The expo converter works but with a strange dependency.
I understand that it's graph normally should look like the exponential function. My "graph" looks like Log inverted by the X axis.
In words (as I'm very poor in math):
when CV IN (from MIDI to CV device) is high (6v for ex.) the osc. frequency is low. When CV IN is low (0v) the frequency is high.
Also it's inverted by the vertical axis. So roughly it's like:
0 ... 6v is 0v = 1000Hz, 1v = 200Hz, 2v = 180Hz, 3v = 170Hz, 4v = 165Hz ...

I can't get a clue where could I make a mistake help confused
These are the pics of my breadboards:
Upper "+" and "-" rails are +9 and -9v, bottom "-" is 0v. I've tried to follow common color rules for wires. Some wires doesn't follow this...
Here is a resistor between Pin 1 and Pin 6 of the TL074 (the osc. board). Without it I get no sound (or it's too low... not sure).
The schematic of the expo is practically the same as here (with CA3046 and OPA 2132). C4A is 2500pf polystyrene (that big green box cap). PNP is 2N3906. Thermal compensation was made using KTY81-110. I think it's not important here (yet).



https://www.muffwiggler.com/forum/files/img_5211_resize_118.jpg

https://www.muffwiggler.com/forum/files/img_5209_resize_159.jpg

https://www.muffwiggler.com/forum/files/img_5208_resize_783.jpg

P.S.
1st Sorry for such a big message. I've wanted it to be understandable as much as possible.

I've repeated the same expo converter using 4558 and KR198NT1A (instead of CA3046, diff. pinout but I've found the doc.). The result is the same. confused

Before going here I was inspired by Ajull Adamsky on YouTube. He's making great efforts and share his experience with people. He was inspired by this place as I think wink
Also I've learned some basics for resistors, potentiometers, diodes and capacitors, some basic info on op. amps and some ICs (like the Shmitt. trigger chip).
I understand:
- how to build a voltage divider, it's basics
- (mostly) how capacitors works (caps can be of diff. types so I know only basics)
- basics of "what is current".
My knowledges are very poor:
- about transistors
- (almost nothing) about complex processes between details.
sleepybongo
FYI: I got the core working nicely using a 2n5485 and a 22pF cap substituting the nf510 and 100pF cap.
chloeprice
I was playing around with the arturia vst of the Jupiter and I noticed, that on high frequencies the sawtooth wave gets steeper in the middle for a while.
Can someone explain why thats the case? (I am 99.9% sure arturia did this on purpose, so it has to be the same with the analog version)
Sdssmith
chloeprice wrote:
I was playing around with the arturia vst of the Jupiter and I noticed, that on high frequencies the sawtooth wave gets steeper in the middle for a while.
Can someone explain why thats the case? (I am 99.9% sure arturia did this on purpose, so it has to be the same with the analog version)]


Do you have the images of the Sine and Triangle outputs?
chloeprice
Sdssmith wrote:
Do you have the images of the Sine and Triangle outputs?
Sdssmith
Thanks for the images. The Tri and Sine waves have the same anomaly in the them and I would have expected it to be filtered out by the VCF somewhat.
Sdssmith
The sawtooth VCO clone I wired up doesn't have the change that the images you posted have and the waveform after the VCF is smoothed.

(Vert: 5V/Div; Hor: 1ms/Div)
Sdssmith
The output from the triangle waveform convertor seems to have a glitch in it. I was curious whether the Arturia has the same thing. The VCF seems to take care of it though.

The Doepfer A110 VCO uses a similar approach and says this in the product description:
Quote:
At the top of the waveform they have a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converters.



(Vert: 5V/Div; Hor: 1ms/Div)
sleepybongo
Last night I experimented some more with alternatives for the nf510.

In the JP8 schematic it says that the saw output of the VCO should oscillate between 10 and 0 volts. In order to get this exact result I had to use a 10nF capacitor for C8. Values below this resulted in a output oscillating between 10 and a voltage above 0 volts.

I tried with a 2n3819 and a 2sk30y as TR2 and found no difference in the saw output.

I'm running everything at +/-13 volts except IC4 which is at +/-15 volts.

It sounds fine with the wave shapers and filter.
chloeprice
Sdssmith wrote:
The sawtooth VCO clone I wired up doesn't have the change that the images you posted have and the waveform after the VCF is smoothed.

Thank you for the scope images. Since this saw wave looks rather unspectacular, would it be noticeable if I replaced the oscillator part with a dco (like in my picture below)? I want to build a "functional-clone" (a clone with the same functions and sound but not necassarily achieved with the same technology). The pros would be that you wouldnt need an expo converter, simpler to build, easier tuning and better tracking (you can always make it worse artificially). I would use the saw just as a core oscillator and do the waveshaping fully analog. Would it be noticeable?
pre55ure
chloeprice wrote:
Sdssmith wrote:
The sawtooth VCO clone I wired up doesn't have the change that the images you posted have and the waveform after the VCF is smoothed.

Thank you for the scope images. Since this saw wave looks rather unspectacular, would it be noticeable if I replaced the oscillator part with a dco (like in my picture below)? I want to build a "functional-clone" (a clone with the same functions and sound but not necassarily achieved with the same technology). The pros would be that you wouldnt need an expo converter, simpler to build, easier tuning and better tracking (you can always make it worse artificially). I would use the saw just as a core oscillator and do the waveshaping fully analog. Would it be noticeable?


Depends on who you ask w00t

However, making a DIY dco isn't really much simpler than making a DIY vco. In a lot of ways your just trading time spent on designing hardware for time spent writing software. They are definite advantages to DCO's but there are also disadvantages. Maybe thats a good compromise for your skill set, IDK. However, it's not guaranteed to be easier and it's also definitely not a JP8 vco. So the question is what is the end goal?
chloeprice
pre55ure wrote:
However, making a DIY dco isn't really much simpler than making a DIY vco. In a lot of ways your just trading time spent on designing hardware for time spent writing software. They are definite advantages to DCO's but there are also disadvantages. Maybe thats a good compromise for your skill set, IDK. However, it's not guaranteed to be easier and it's also definitely not a JP8 vco. So the question is what is the end goal?

My endgoal is to build a Jupiter 8-like polysynth that sounds and can be used the same way as a real one. The sound will not be exactly the same, but the goal is to have the same workflow. So for example I wouldnt have a replacing a roland filter chip with a "regular" lm13700 ota filter.

And if something makes the job a thousand times easier (like using dcos instead of vcos) but doesnt change the end result much, Ill go with it. Even if its not like in the original. (for me dcos are a lot easier since, how you said, thats where my skills are)
indigoid
DCOs would make it more like a Juno-106, no? With all the ups and downs of that approach.

“Tiergrinder” on YouTube already built a 4-voice clone of a Jupiter 8. It sounds glorious

If you’re not expecting it to Sound Correct, you could save a whole heap of effort by using Alfa/CEM/SSI chips

(Or by building a convincing Jupiter front panel that is actually just a MIDI controller!)
chloeprice
indigoid wrote:
DCOs would make it more like a Juno-106, no? With all the ups and downs of that approach.

“Tiergrinder” on YouTube already built a 4-voice clone of a Jupiter 8. It sounds glorious

If you’re not expecting it to Sound Correct, you could save a whole heap of effort by using Alfa/CEM/SSI chips

(Or by building a convincing Jupiter front panel that is actually just a MIDI controller!)


Yes, the oscillator would be similar to that in the 106. I also thought about using vco ics. It would be amazing if someone here could post the raw audio of a jupiter 8 (or vco clone) saw wave, so I could compare these in a blind test. If I cant tell which is which, it is good enough for me.
Jackdamery
indigoid wrote:

“Tiergrinder” on YouTube already built a 4-voice clone of a Jupiter 8. It sounds glorious


dikkietrom
https://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+5.0232 72298708815+65+5+43%0At+-96+144+-32+144+0+1+0.594562868214435+0.612860 2904058269+100%0At+64+144+16+144+0+1+0.0000947016623047172+0.018243381 150190165+100%0Ar+-32+96+-32+32+0+470000%0AR+-32+32+-32+-16+0+0+40+13+ 0+0+0.5%0Aw+-32+160+-16+160+0%0Aw+-16+160+-16+224+0%0Aw+-16+160+16+160 +0%0Ar+-16+224+-16+288+0+4700%0Ag+64+144+64+192+0%0At+64+304+-16+304+0 +-1+2.8494753164536215+-0.5955437557409056+100%0Ar+-16+320+-16+368+0+2 200%0AR+-16+432+-16+464+0+0+40+-13+0+0+0.5%0Ar+64+304+160+304+0+4700%0 Aa+336+304+160+304+8+13+-13+1000000+0.00005404104120164823+0+100000%0A r+336+320+336+368+0+470000%0Ag+336+368+336+432+0%0Aw+-32+128+-32+96+0% 0Aw+-32+96+336+96+0%0Aw+336+96+336+224+0%0Ac+224+224+288+224+0+1e-9+-5 .404158161206025%0Aw+288+224+336+224+0%0Aw+336+224+336+288+0%0Aw+160+3 04+160+224+0%0Aw+160+224+224+224+0%0Aw+16+128+16+32+0%0Aw+16+32+400+32 +0%0Aa+400+48+560+48+8+13+-13+1000000+-0.0000947016623047172+0+100000% 0Ag+400+64+400+112+0%0Ar+400+32+400+-48+0+270%0Ac+400+-48+560+-48+0+1e -9+-9.470260932106562%0Aw+560+-48+560+48+0%0Aj+480+-192+480+-128+32+-4 +0.00125%0Aw+400+-48+400+-128+0%0Aw+400+-128+464+-128+0%0Aw+496+-128+5 60+-128+0%0Aw+560+-128+560+-48+0%0Ar+560+-208+560+-128+0+4700%0Ad+560+ 192+560+128+2+default%0Ag+560+192+560+240+0%0Ad+560+-208+656+-208+2+de fault%0Ac+656+-208+656+48+0+1e-10+-24.47020538982504%0Ar+560+48+656+48 +0+1800%0Aw+480+-192+480+-208+0%0Aw+480+-208+560+-208+0%0Aa+816+32+912 +32+8+15+-15+1000000+10+9.470152420067048+100000%0Aw+656+48+816+48+0%0 Aw+816+16+816+-48+0%0Aw+656+-208+912+-208+0%0Aw+912+-208+912+32+0%0Ac+ 816+-48+736+-48+0+1e-8+10%0Ag+736+-48+736+0+0%0Aw+736+-48+736+-128+0%0 Ar+736+-128+816+-128+0+10000%0Aw+816+-128+816+-48+0%0Ar+816+-128+864+- 128+0+3000%0AR+864+-128+864+-176+0+0+40+13+0+0+0.5%0Aw+560+48+560+128+ 0%0AO+560+128+672+128+0%0A172+-448+128+-496+128+0+7+3.9+15+0+0+0.5+Vol tage%0Aw+-16+320+-96+320+0%0Aw+-368+128+-368+320+0%0Ar+-176+320+-96+32 0+0+820000%0Aw+-176+144+-96+144+0%0Ar+-96+144+-96+224+0+1000%0Ag+-96+2 24+-96+256+0%0Aa+-272+144+-176+144+8+13+-13+1000000+-0.000005946169092 556367+0+100000%0Aw+-176+320+-368+320+0%0Ar+-448+128+-368+128+0+100000 %0Ag+-272+160+-272+224+0%0Aw+-176+144+-176+64+0%0Ac+-368+64+-176+64+0+ 1e-8+-0.5946228554247293%0Aw+-272+128+-368+128+0%0Aw+-368+128+-368+64+ 0%0Aw+-368+64+-368+0+0%0Ar+-368+0+-272+0+0+19000%0A174+-272+0+-192+0+0 +1000+0.5+Resistance%0Aw+-176+0+-176+64+0%0Ar+-368+0+-368+-96+0+100000 %0Ar+-368+-96+-480+-96+0+2200%0Ag+-480+-96+-480+-32+0%0Ar+-368+-96+-36 8+-176+0+100000%0A174+-288+-224+-432+-176+0+100000+0.5891000000000001+ Resistance%0AR+-448+-224+-448+-192+0+0+40+-13+0+0+0.5%0AR+-288+-224+-2 88+-272+0+0+40+13+0+0+0.5%0Aw+-224+-16+-224+-64+0%0Aw+-224+-64+-176+-6 4+0%0Aw+-176+-64+-176+0+0%0Ar+-368+320+-368+384+0+220000%0AR+-368+384+ -368+432+0+0+40+-13+0+0+0.5%0A174+-16+432+48+368+0+5000+0.490100000000 00004+Resistance%0Aw+-16+432+48+432+0%0Aw+48+400+48+432+0%0Ao+57+32+0+ 12290+10.002215884172562+0.0001+0+1%0A
Jarno
Nice
dikkietrom
I am working on a JP8 voice card with kicad hierarchical sheets, autoplacement and routing. I know there is an opinion about this but I can make ok boards in 15 minutes. Just spend 3 days on the scheme for vco, IR3109 and the BA662. For the env I will use the electricdruid pic. If a few join the project we can have the voice scheme fairly quick. I am not going to prototype with breadboard, that will take ages. I am keen on getting things done regarding this. It is just a shitload of matched transistors, caps and resistors.
I have an autocalibration algo that scans the volt/octave/vco.
Will make THT subboards first with sockets assembled so that we can try out different components quickly without soldering. When the scheme is proven correct and we have the proper bom I will make it as compact as possible with smd and have it assembled. It is about time for this, who needs another cem3340?

Browse the kicad project in my signature to get a feel for it, I'l post a movie about my workflow and hope to raise some enthousiasm.
groove
dikkietrom wrote:
Browse the kicad project in my signature to get a feel for it, I'l post a movie about my workflow and hope to raise some enthousiasm.


This is awesome - nice work so far.
dikkietrom
workflow youtube
dikkietrom
Some resistor values have a G behind them, on the pcb they are specified as R25G types. The R25's are carbon. I think the R25G's are non inductive, can anyone confirm?
groove
dikkietrom wrote:
Some resistor values have a G behind them, on the pcb they are specified as R25G types. The R25's are carbon. I think the R25G's are non inductive, can anyone confirm?


I would take that to mean 1/4 watt 2%. Would non-inductive matter in low frequency circuits like a synth?

https://es.scribd.com/document/246667230/K48-50-Carbon-Film-Resistors
dikkietrom
I'l go with that thnx, I located them on the board in the meanwhile also

dikkietrom
All connector and sections interconnects are done and 16 of the 25 sections. I need one more round to finish the initial design.
Board so far.




Some module controller board sections are needed too for full functionallity, about half of the board. The rest is digital stuff that can be replaced with arduino + dac or just pots.

Will use the jupiter 4 discrete adsr cause suspect Roland to have transfered that to an IC just like the vcf. Remarkable is that Roland used other cap en resistor values for the jupiter 4 but not for the juno60. Any OTA vcf design with the same cap/resistor values will sound close I guess.

I will not post anymore here regarding the voice, this topic is about the vco. It triggered the idea to make the voice, thanks!
peloazul
Super exciting, dikkietrom!
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