Updated SSI2130 VCO Datasheet available...

[Rengel]

Thank you,
no I populated the pcb myself - was my first time to do reflow soldering at home. Unfortunatly the pcb is a little bit to small and one fell off at the end of the soldering process. The frequency of the fan / resonating sheet changed with temperature and at some point the pcbs started to move over the grill of my pizza oven.

[neil.johnson]

Ah, I see
One suggestion: next time get your PCB fab to panelise up the boards for you into one larger board with each board routed with mouse-bites to hold them in. One larger board is easier to handle securely than lots of little ones.

Neil

[anotherlin]

no I populated the pcb myself - was my first time to do reflow soldering at home. Unfortunatly the pcb is a little bit to small and one fell off at the end of the soldering process. The frequency of the fan / resonating sheet changed with temperature and at some point the pcbs started to move over the grill of my pizza oven.

You mean, you used an actual "cooking" oven?
It seems to work pretty well! Resistors, capacitors, and SOT-23s look good. However, at least one of the QFN32 has some solder bridge.

By the way, what is your plan for your module?
Is it for sale as complete module or DIY? I would be interested by one.
If you've looked at the previous posts, I've designed one for the yet to be available SSI2131.
But I've a few SSI2130 at hand that I need to test.

[Rengel]

Hello again,
completing my test-circuit - the module seems to work as expected. The only thing I noticed is the sine-shaper: at lower frequencies there is a little 'bump' where the direction changes - but I think that is normal.

Bye

[Rengel]

Hello again,
and that mixer is quite cool, too - have to test that more.

Bye
Ray

[neil.johnson]

completing my test-circuit - the module seems to work as expected. The only thing I noticed is the sine-shaper: at lower frequencies there is a little 'bump' where the direction changes - but I think that is normal.

How are you coupling the triangle into the sine shaper input?

Neil

[neil.johnson]

and that mixer is quite cool, too - have to test that more.

Oh yes There are many things you can do with that mixer!

Neil

[Rengel]

Hello,

-- You mean, you used an actual "cooking" oven?
Yes a normal small pizza oven - OK baking pizza after using it as reflow oven isn't that good - but it's a cheap solution.

-- It seems to work pretty well! Resistors, capacitors, and SOT-23s look good. However, at least one of the QFN32 has some solder bridge.
Yes was a little bit to much solder paste I think, but you can remove the bridges quite easy.

-- By the way, what is your plan for your module?
-- Is it for sale as complete module or DIY? I would be interested by one.
Don't know at the moment - 1st take look at the schematic. As I already wrote - I didn't route all SSI pins to the socket.
If you can live with that I have some spare pcbs - at the moment I don't have any SSI2130 left, so I couldn't populate them anyway.

Bye
Ray

[Rengel]

Hi Neil,

-- How are you coupling the triangle into the sine shaper input?
Quit like it is in the data sheet - coupling AC with about 10µ (ceramics) and then using a divider 4k to 4k7 into GND. The other pin is connected to GND via 4k7. I made some jumpers in my test circuit - don't think that the open (not jumpered parts) do any harm.

Ray

TEST_VCO_V02b.pdf

(32.99 KiB) Downloaded 13 times

[neil.johnson]

-- How are you coupling the triangle into the sine shaper input?
Quit like it is in the data sheet - coupling AC with about 10µ (ceramics) and then using a divider 4k to 4k7 into GND. The other pin is connected to GND via 4k7. I made some jumpers in my test circuit - don't think that the open (not jumpered parts) do any harm.

Yes, so at low frequencies the capacitor will reduce the signal going into the sine shaper. It's okayish for audio frequencies but not good for LFO, in which case you need the DC-coupled circuit instead. See datasheet Figure 6.

Neil

[oldenjon]

Just saw the 'ideal diode' 3-way crossfader in the datasheet. Very cool. Anyone know of a circuit for a 4-way crossfader? Would love to get sine in the mix.

[anotherlin]

Don't know at the moment - 1st take look at the schematic. As I already wrote - I didn't route all SSI pins to the socket.
If you can live with that I have some spare pcbs - at the moment I don't have any SSI2130 left, so I couldn't populate them anyway.

I've taken a look at schematics, looks good for me.
I don't need all 2130 pins, there's just so many functionalities and for a first test, that's not needed.
It's much more useful to have voltage regulator, references, and basic timing caps already installed.

I send you a PM.

[neil.johnson]

Don't know at the moment - 1st take look at the schematic.

Looks good
I would add a 10k pull down on the HARD SYNC pin - if it floats then the VCO will stop.

Neil

[anotherlin]

I would add a 10k pull down on the HARD SYNC pin - if it floats then the VCO will stop

Damn, I've missed that. :(
Datasheet explicitely states that HARD SYNC must be grounded/pulled down if unused.

[neil.johnson]

I would add a 10k pull down on the HARD SYNC pin - if it floats then the VCO will stop

Damn, I've missed that. :(
Datasheet explicitely states that HARD SYNC must be grounded/pulled down if unused.

Well, you can do that off-board, but just would have been a little bit easier

Neil

[Rengel]

Don't know at the moment - 1st take look at the schematic.

Looks good
I would add a 10k pull down on the HARD SYNC pin - if it floats then the VCO will stop.

Neil

Yes I noticed that already - I've made a small test-board that has a pull-down and a capacitor for AC-coupling from an input pin. Unfortunately - as ever - I put the pull-down on the wrong side of the capacitor and was then wondering why the modules wouldn't work

[Rengel]

I would add a 10k pull down on the HARD SYNC pin - if it floats then the VCO will stop

Damn, I've missed that. :(
Datasheet explicitely states that HARD SYNC must be grounded/pulled down if unused.

Well, you can do that off-board, but just would have been a little bit easier

Neil

Yes would be easier if it was on the pcb - as I used copper-fill GND is right next to the socket pin, so I can put an additional resistor there easily.

Ray

[Rengel]

Hello,
I was a little confused for a moment when I was looking further n the mixer - but the mixer cannot do anything about that:

The input of the comparator is connected to the output of the triangle - therefore the pulse is symetrical with the edge of the saw.
Doesn't any harm in the first place and for the mixer it makes then much more interesting outputs:

If you want the pulse in phase with the saw / square output, it would be better to connect the input of the comparator to the saw output - but for the mixer that would make things a little bit less interesting.

Bye
Ray

[neil.johnson]

If you want the pulse in phase with the saw / square output, it would be better to connect the input of the comparator to the saw output - but for the mixer that would make things a little bit less interesting.

This is mentioned a bit on page 7 of the datasheet, you get slightly different results if you drive the PWM comparator with the triangle compared to sawtooth when the control signal is varying.

Neil

[Stab Frenzy]

I've run into a peculiar quirk when testing my prototype on a variety of Eurorack power supplies. I have one supply where the -12V rail comes up around 8ms after the +12V, using this supply the 2130 locks up with the voltage on tcap at around 3.5V. I'm not using the Strobe pin in this design so it's not broken out, otherwise I'd see if I could reset it after both rails were up. The 2130 is supplied by +5V and -5V regulators, the -5V rail floats at around +0.7V until the -12V rail is up.

Any thoughts on what's going on internally and how it might be avoided? This situation isn't that unlikely in the wild west of Eurorack power so I'd like to design the module in a way that can tolerate it on startup.

I've encountered the exact same issue, anyone else?

Is there a possible solution for this?

Have you confirmed it works fine on other supplies? Some more testing with mine found that it would lock up with the 8ms delay between rails, but a longer or shorter delay wouldn't be an issue. None of the suggestions I received made any difference to the issue, so I'm hoping it's just a one off issue with that particular unit.

[neil.johnson]

I've run into a peculiar quirk when testing my prototype on a variety of Eurorack power supplies. I have one supply where the -12V rail comes up around 8ms after the +12V, using this supply the 2130 locks up with the voltage on tcap at around 3.5V. I'm not using the Strobe pin in this design so it's not broken out, otherwise I'd see if I could reset it after both rails were up. The 2130 is supplied by +5V and -5V regulators, the -5V rail floats at around +0.7V until the -12V rail is up.

Any thoughts on what's going on internally and how it might be avoided? This situation isn't that unlikely in the wild west of Eurorack power so I'd like to design the module in a way that can tolerate it on startup.

Besides the grounding of STROBE, not connecting the bottom pad to ground, and not grounding the mixer control inputs, it looks like you have a power sequencing problem.

If your -5V rail is "floating" at +0.7V then I would be very concerned about that. 0.7V is a forward-biased diode so current is flowing into that rail and somewhere a diode is holding it there.

One thing you could try is a Schottky diode from the -V rail to common (anode at V-, cathode at common). This would keep the V- rail below the normal silicon diode switch-on voltage. Worth a try?

Neil

[oldenjon]

If the current is supposed to be symmetrical (which is the part I’m not sure about) wouldn’t it be better to use a 500k resistor directly on the LIN FREQ pin (R11 on the below schematic) for supplying the 5uA. And then leave out the level-shift resistor R4 on above schematic. This would give a symmetrical current since the comparator correctly detects the zero-crossing of the input

If you do that then in effect you set the carrier frequency to 0.

No, but it might actually be desirable to have a potentiometer connected to +/-5V instead of the Vref offset at the InTZFM summing amp though. Maybe via a switch. That would give you a symmetry control like Rubicon right?

[neil.johnson]

If the current is supposed to be symmetrical (which is the part I’m not sure about) wouldn’t it be better to use a 500k resistor directly on the LIN FREQ pin (R11 on the below schematic) for supplying the 5uA. And then leave out the level-shift resistor R4 on above schematic. This would give a symmetrical current since the comparator correctly detects the zero-crossing of the input

If you do that then in effect you set the carrier frequency to 0.

No, but it might actually be desirable to have a potentiometer connected to +/-5V instead of the Vref offset at the InTZFM summing amp though. Maybe via a switch. That would give you a symmetry control like Rubicon right?

Yes that's right. And similar to the Rubicon, when set to the extreme ends of the range you will get linear FM, and also when set to the middle position the oscillator will stop (Rubicon2 manual page 24).

Neil

[lickspittle]

Neil,

Can I point out a couple of (what I believe to be) typos in the data sheet which you may want to pass on to your contacts at SSI.
In Figures 8 & 9 the HF Tracking pin is listed as 7, should be 6.

Also there seems to be a general conflation throughout of the terms "Pulse" (the waveform), "Pulse Width" (the duty cycle) and "Pulse Width Modulation or PWM".

Cheers.

[neil.johnson]

Hi lickspittle,

Thanks, I'll pass on your corrections!

Neil