Front Panel Proof Reading Thread

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ashleym
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Re: Front Panel Proof Reading Thread

Post by ashleym » Mon Feb 03, 2020 2:47 pm

the rotary starting with 5 is sequence length.

Analogue for UK English speakers. Like synthesisers.

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batchas
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Re: Front Panel Proof Reading Thread

Post by batchas » Mon Feb 03, 2020 3:38 pm

ashleym wrote:
Mon Feb 03, 2020 2:47 pm
Analogue for UK English speakers. Like synthesisers.
:tu:
I was not sure if it was also US/UK difference (Analogue Systems etc).
ashleym wrote:
Mon Feb 03, 2020 2:47 pm
the rotary starting with 5 is sequence length.
Yes but why not 4 steps sequence? Or 3? Can be really fun actually.
I guess it's more practical/affordable with a standard 12 positions rotary switch than a 16...
As I often make it more complicate than necessary, I'd ask myself do I use more 3 or 4 steps than 11 or 13.
And prob. end up using a 16 positions anyway!
FS: New Orgone Accumulator MK2 for BugBrand/FRAC
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ashleym
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Re: Front Panel Proof Reading Thread

Post by ashleym » Mon Feb 03, 2020 5:01 pm

I think we have to blame the French for that spelling. They exported a lot of words to us, we pronounce most of the letters and usually end up only pronouncing half the word.

There is as much etymology of sequencers here! I agree with the switching of sequencer length. I’ve got an unfinished MFOS sequencer, I’ll look at the length options and circuit around the values (having an engraved FPD panel I won’t be making any changes). As you say, a good number of people would have fun with 2,3 or 4 steps rather than 11 or 13 (forgive me all you jazzers and proggers).

I laid out my sequencer in parallel lines do the controls match my other bits. My own inclination is that set up.

In ye olde days you got 12 step sequencers from Roland. Isn’t That why some of the early Human League songs are in 3/4?

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Paradigm X
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Re: Front Panel Proof Reading Thread

Post by Paradigm X » Tue Feb 18, 2020 9:51 am

i actually liked the version with the component overlays fwiw...

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kriaction
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Re: Front Panel Proof Reading Thread

Post by kriaction » Mon Mar 23, 2020 4:20 pm

Hi Ya'll :pbear:
I'm working on these two projects for many many months now. I have finally finished but it's from more or less one month that I keep on staring at the screen searching for errors without sending them to production.
They are both based on MFOS projects.
The first one is the 16 step sequencer with vary-clock mod, I just added another set of gates with LED driver and a rotary switch to change the maximum output voltage (low, medium and high). The two sets of gates share the same LED which is an RGB (common cathode), therefore one set will turn on only one specific color and the colors will be mixed if two steps are on at the same time.



The second one is based on the miny synth plus, to which I added: a third VCO (Ray Wilson's design), the envelope of the Mark II, headphone amplifier of the Expander, octave selection for all the VCOs (Ray Wilson's design), an independent mixer (in the mini synth filter and mixer are merged), a triangular 2 sine wave converter for the LFO (which is independent from the other waves) and a sawtooth 2 triangular wave converter for the VCO3. Every mod except the additional VCO has been integrated onto a PCB that I designed.
I then decided to make it completely modular.



Both projects use bananas (red for output, yellow for input, blue for gate and green for 0V). The squared slots you see (4 in the sequencer and 2 in the synth) are SPST momentary switches (https://cdn-reichelt.de/bilder/web/xxl_ ... T_1_WS.png) which are soldered onto custom PCBs and mounted to the front panel using screws. The PCBs are mounted to the front panel using an aluminum plate kept in place using mounting brackets to some of the knobs and bananas of the front plate.
Both panels will be black with white silkscreen and I am going to use a couple of black hammond chassis as enclosures. Each enclosure has its own wall wart PCB.

Any suggestion is very much appreciated :mrgreen:

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Re: Front Panel Proof Reading Thread

Post by ashleym » Wed Mar 25, 2020 8:20 am

Looking at the sequencer panel first, most of what i suggest is style rather than error. I dont see any obvious errors- well done for that. Tiny hair splitting and only meant as constructive especially in relation to the obvious hard work you have already put into this.

IN the gate/trigger the "multi" box is low in relation to the labels around it. "Clock source" is low. Does "glide out" need to be that and not just "glide" as you have coloured bananas to show something is in or out. This also applies to some of the other outs. EXT clock doesn't say in. Is there an overall 'style guide' you are working to? I see you have most things as 'long hand' but you do have trig and trigger- thats why I ask.

As an aside, I included a quantiser with my MFOS sequencer (and the range control and A & B outputs).

For the oscillator panel:are the fine tune controls 5-0-5 or 0-10, ie is 12 o'clock in tune or half of the maximum fine tune offering plus tuning only? Could CV IN and IN be CV and Signal? Both will have the in coloured banana. There is variation in the size of the numbering and lines around the control knobs. I can see the reason for fit and importance but i see some inconsistencies. You'll know if what you've done makes sense. I will ask if you need 3 v/oct inputs? VCO1 has LIN CV, VCO2 has none and VCO3 has MOD- for lin mod (or whatever you prefer to call it). This is a key part of what makes modular fun- modulation, the more the merrier. Could gnd sockets be reduced, freeing space for more mod options? In the mixer i can't see a VCO1 level, does this have a fixed 'max' output? i take it the 1, 2 and 3 sockets are external ins? See, it does work to just label the basics and use the banana colours to indicate in/out. Again, this is style guide consistency. I assume you have 1/4' output jacks for the main and headphone out? Squeeze in another attenuator if you can.

I am 100% behind your octave switching switches.

Good luck. this looks great.

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Re: Front Panel Proof Reading Thread

Post by JohnnyBang » Fri Mar 27, 2020 6:28 am

Hellow Members!
I've been long time around in this forum, but now I'm finally a member an can start sharing my projects and thoughts.
I design and fabricate my DIY Synth all on my own and I got stuck with my LM13700 VCA. It's already manufactured and doesn't work.

If anyone can find the Mistake or can lead to finding the mistake, I'm willing to give you some award. Either you could for example get one of my modules or something else.

I really want it to funktion correctly really bad and need to find the mistake...

The shematic:


The frontpanel:


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devinw1
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Re: Front Panel Proof Reading Thread

Post by devinw1 » Fri Mar 27, 2020 1:39 pm

JohnnyBang,

When you say it doesn't work do you get any sound or it just doesn't modulate?

The way you are applying the CV will not work very well for the LM13700. With a CV that only goes to 0 like you have, the VCA will not be able to shut off. The bias input wants a current, and sits about 2 diode drops from the negative rail (so about -10.8 volts in a Euro configuration) so it will work better to use a PNP transistor with the output of your CV summer going to a resistor into the emitter, ground the base and the collector goes to Iabc on the LM13700. Or you can put a ~10k resistor after your 22k to -12V.

Additionally, since you have an output op amp after the OTA, you don't need to use the Darlington buffers at all. You can use the output amp in a transimpedance configuration.

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kriaction
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Re: Front Panel Proof Reading Thread

Post by kriaction » Fri Mar 27, 2020 2:25 pm

Thank you ashleym, I very much appreciate all the suggestions and the fact that you took the time to write them down.
ashleym wrote:
Wed Mar 25, 2020 8:20 am
IN the gate/trigger the "multi" box is low in relation to the labels around it. "Clock source" is low. Does "glide out" need to be that and not just "glide" as you have coloured bananas to show something is in or out. This also applies to some of the other outs. EXT clock doesn't say in. Is there an overall 'style guide' you are working to? I see you have most things as 'long hand' but you do have trig and trigger- thats why I ask.
You absolutely have a point regarding the consistency of the labels, I need to fix it, it could save me some words but I'd like to keep the "out" or "in" sometimes anyway.
ashleym wrote:
Wed Mar 25, 2020 8:20 am
As an aside, I included a quantiser with my MFOS sequencer (and the range control and A & B outputs).
I thought about that too, unfortunately I don't have enough space for the board. It was that or the vary clock...and I've always loved to be able to ratchet sequences since the first time I discovered the technique listening to Tangerine Dream :hyper: I will have a quantiser in the future, for sure.
ashleym wrote:
Wed Mar 25, 2020 8:20 am
For the oscillator panel:are the fine tune controls 5-0-5 or 0-10, ie is 12 o'clock in tune or half of the maximum fine tune offering plus tuning only?
That's another good point. Having them 5-0-5 would improve the way I can play with the pitch, and it should be just a matter of trimmers and calibration. Never thought of it!
ashleym wrote:
Wed Mar 25, 2020 8:20 am
I will ask if you need 3 v/oct inputs? VCO1 has LIN CV, VCO2 has none and VCO3 has MOD- for lin mod (or whatever you prefer to call it). This is a key part of what makes modular fun- modulation, the more the merrier.
Actually now that I think about it, I could probably even the number of cvs between 1v/oct and linear...
ashleym wrote:
Wed Mar 25, 2020 8:20 am
In the mixer i can't see a VCO1 level, does this have a fixed 'max' output?
I left it out from the mixer section. The other VCOs have only two waveforms so it's either one or the other (thus I can use only one switch). VCO1 has 4 waveforms so instead of using a rotary or two swiches I decided to just leave it out. I can use the ext to patch it in, plus I can sum at the input so I can easily have two of the waveforms in the mixer and one modulating a VCO for example.
ashleym wrote:
Wed Mar 25, 2020 8:20 am
I assume you have 1/4' output jacks for the main and headphone out?
yep

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Re: Front Panel Proof Reading Thread

Post by ashleym » Fri Mar 27, 2020 6:02 pm

kriaction wrote:
Fri Mar 27, 2020 2:25 pm
Thank you ashleym, I very much appreciate all the suggestions and the fact that you took the time to write them down.

yep
:banana:

That is why you posted, I offer you a bit of help and I am sure you will do the same or even just inspire people with your build. I understand more about your decisions. I hope the build goes well and stay safe and healthy.

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Re: Front Panel Proof Reading Thread

Post by JohnnyBang » Sun Mar 29, 2020 9:51 am

A big thank you first of all. I am struggling with this complicated 13700 for a long time :eek:
devinw1 wrote:
Fri Mar 27, 2020 1:39 pm
When you say it doesn't work do you get any sound or it just doesn't modulate?
There's strange behaviour going on. Sometimes it worked almost, but most of the time there is just noise and clicking. When it works, there is an outputsignal, that gets modulated, but just for short.
devinw1 wrote:
Fri Mar 27, 2020 1:39 pm
Or you can put a ~10k resistor after your 22k to -12V.

Additionally, since you have an output op amp after the OTA, you don't need to use the Darlington buffers at all. You can use the output amp in a transimpedance configuration.
So I would like to mod this existing circuit to get it working, without printing a new pcb for now.
What would you suggest to to do?
would the Resistor to the negative Rail, solve the CV Problem? :love:

Then I can mod the output Buffer to a TIA. That'd be possible.

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devinw1
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Re: Front Panel Proof Reading Thread

Post by devinw1 » Sun Mar 29, 2020 3:11 pm

JohnnyBang wrote:
Sun Mar 29, 2020 9:51 am

There's strange behaviour going on. Sometimes it worked almost, but most of the time there is just noise and clicking. When it works, there is an outputsignal, that gets modulated, but just for short.
OK, that sounds like there's something else going on. I'll look at your schematic some more and think about it. But, when you have intermittant problems, it usually means there is something wrong with the actual construction of the circuit. Look for solder bridges, bad/cold solder joints, bad DIP sockets, little stray balls of solder/metal, etc.. Maybe reflow all the joints to be sure.

As far as the CV mod, yeah you can just solder that 10k from the node after the 22k to the -12V rail and it should work better as a VCA.

BTW, one final thing; you have this in the Front Panel Proof thread, so if you want more exposure to some of the REALLY smart and helpful people here, make a new thread with a descriptive title in the DIY forum. :tu: :tu:

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Re: Front Panel Proof Reading Thread

Post by JohnnyBang » Mon Mar 30, 2020 12:10 pm

devinw1 wrote:
Sun Mar 29, 2020 3:11 pm

OK, that sounds like there's something else going on. I'll look at your schematic some more and think about it. But, when you have intermittant problems, it usually means there is something wrong with the actual construction of the circuit. Look for solder bridges, bad/cold solder joints, bad DIP sockets, little stray balls of solder/metal, etc.. Maybe reflow all the joints to be sure.
That was the first thing I did. I resoldered every joint about 5 times :hihi:
And I tried two different pcbs.
I checked almost all connections.
It seems like every signal gets lost in the 13700.
devinw1 wrote:
Sun Mar 29, 2020 3:11 pm

BTW, one final thing; you have this in the Front Panel Proof thread, so if you want more exposure to some of the REALLY smart and helpful people here, make a new thread with a descriptive title in the DIY forum. :tu: :tu:

I will start a new thread at a better place :)
Thank you :)

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