How to connect CD4070 to power circuit in schematic?

Yes, I did move those. I realized in the earlier schematic I posted that I had not routed any power to the circuit. I forgot to connect the +12V and -12V to any of the 100n caps so it was just running in a circle through the diodes and electrolytics to ground. I pulled up a previous schematic that I had used, referenced it, and placed the +/-12V symbols in the same place that they were on in this other schematic. I’ll move them back to where I had them before. Thanks for the help!

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Also, pins 4, 6 and 8 on the IDC header aren’t connected to ground. :wink:

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@analogoutput would you be willing to look at the original schematic I posted towards the top of this thread and see if you could tell me what the RV3 B100k potentiometer is being used for here? (It’s on the far left about 1/3 up from the bottom.) The rest of the pots and jacks are labeled except that one. I know sometimes you can tell just by looking at the schematic but I don’t have the knowledge to be able to decipher the circuit in order to tell.

It’s being used as an offset for the CV input below it. The voltage from the pot is added to the voltage from the jack using the TL074 in an inverting summing amplifier configuration.

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So would you just label it on a panel as “Offset?”

I’d label it as whatever it does, not just ‘offset’. It’s like a manual CV to adjust a parameter, so label it after that. Cheers!

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Is there a way to tell what value of pots were used for all of the other potentiometers aside from the RV3? That’s the only labeled as a B100k. I emailed the guy who created the circuit but received no response.

I also just noticed that one of the pots is actually labeled as “CV Offset.” So maybe I’ll label this one as “Manual CV?”

RV4 is an input attenuator, it’s value determines the input impedance of the CV in. I’d recommend you use B100k here. The other ones are voltage dividers between two rails, so their value is not critical. I’d recommend anything between B10k and B100k, but basically any value will work.

Regarding the labeling, what does it actually do? “CV offset” and “manual CV” are names which don’t say anything, they give me no clue what I will hear if I twist the knob. Is it a frequency, is at resonance, is a bitcrushing amount? I’d label it after that.

Also, notice that that RV1 and RV2 are marked as trimpots, not panel-side potentiometers. Not sure whether that’s intentional?

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I get what you’re saying about the labels. I’m asking because I was planning to get both the panel and the PCB made at the same time. I wouldn’t be able to hear what they do before I label it. This is too complicated for me to put on a breadboard. I was hoping the guy that made the schematic would answer but after 2 weeks I don’t think that’s going to happen. I’m also not sure what the switches do either. Ugh…

How can you tell that RV1 and RV2 are trimpots? Based on how they’re used in the circuit? They look identical to me as say RV3.

RV3&4 have an arrow on the wiper connection, RV1&2 have a little bar.

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Thank you! Completely missed that! :woman_facepalming:

image

That’s a regular pot, with a little arrow

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That’s a trim pot, with a little line

The switches seem to do some logic concerning the ‘gate’ input, not sure what the actual function is…

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Watch the loading, though. Unless there’s some reason you actually want non-linear pot response, normally you want the pot value to be less than or at least not much more than the load.

RV1 just connects to an op amp input so anything should work there.

RV2 drives a 10k to a virtual ground so for linear response would best be 1k or 2k or 5k. But 1k would draw 12 mA, probably too much. 10k would be okay. 100k would give non linear response. Though if it’s really a trim pot it maybe doesn’t matter that much.

RV3 is labeled 100KLIN but again drives a 10k to a virtual ground. However here (and possibly at RV2?) the non-linear response you’d get might be intentional. It makes it more like a log pot.

If you want log-like response there, you can do that.

RV4, same thing, 10k to virtual ground, giving log-like pot behavior if you use a 100k linear pot.

If you don’t want log-like behavior I’d say R18, R26, R30 should be 100k, and 100k for RV4. The response won’t quite be linear but close enough.

In fact I’d say those resistors should be 100k anyway, and if you want log-like behavior, use log pots. Otherwise the input impedance at J6 is too low when RV4 is turned up.

On the other hand I’d use 10k resistors for R17, R24, R31. Why use 100k there but not in the preceding and following stages? Seems silly. 10k is generally better for lower noise floor when input impedance is not an issue. 10k will draw more current through R17, 1.2 mA vs 0.12 mA; if you care about that, keep 100k.

Is there an RV5? I don’t see one but then I didn’t see RV4 for a while.

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I agree with you, that’d be the real solution here.

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From the description I guess the CV controls the frequency of the internal oscillator which then determines the coarseness of the sample and hold that does the sample rate reduction. If you wanted a 2-word description of it’d be something like “crush level”. Note that turning the rate up turns the effect down, so the panel pot may need to be wired backwards from the usual. Maybe. Or maybe the response is inverted in the circuit, I can’t tell.

RV1 is labeled “pulse length” so maybe governs the duty cycle of the oscillator? Not clear what that accomplishes. Anyway it’s a trim pot so labeling is less of a concern. RV2 is labeled “CV offset” and sets a baseline level, i.e. maximum crush level, looks like. RV3 gives a manual adjustment of the crush level, which is added to the CV, and RV4 controls the sensitivity of the module to the crush level CV.

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Thanks so much for your help! I really appreciate it. I’m changing all of the resistor values to the ones you suggested. I’d prefer a linear response.