The Corruptor - CMOS Ring Modulator

[anotherjim]

At minimum resistance, that gate/release trimmer should definitely stop the oscillator (it will then be forcing the inverter input to ground, whatever the signal does, then it's holding the oscillator input high via the diode, bypassing the timing). Have you got a diode the wrong way around?

[peterg]

Diodes are good. The oscillation starts at the straight joined inverters and continues throughtout the circuit

[digi2t]

Should the unused quad on the 4070 be tied high (or low)?

[Freppo]

Should the unused quad on the 4070 be tied high (or low)?

The unused inputs on the CD4070 can be tied either both high or both low. It doesn't matter.

[digi2t]

Well, here's my initial layout for the "all bells and whistles" version. I've gone over it one time, and I think it's OK, but another set of eyes would be welcome. I'll go over it again over the next few days. Let me know if you see something amiss.

[Freppo]

Well, here's my initial layout for the "all bells and whistles" version. I've gone over it one time, and I think it's OK, but another set of eyes would be welcome. I'll go over it again over the next few days. Let me know if you see something amiss.

Sweet! That's great. I'll have a look later this weekend after I get back home from x-mas.

[digi2t]

Did a second pass, one cut under IC4 in the wrong place (for +9 jumper to pin 16). Should be one hole to the left. Other than that, everything seems to follow the schematic.

I'll update it tonight, and include the BOM.

Crap... I really want to build this now, but I've got too much on my bench at the moment. I have to make some room.

[digi2t]

Corrected and updated.

[peterg]

Need some debug help please. I am working on the original circuit. There were problems with oscillation when I breadbboarded the circuit. I resolved that by swapping 4069 chips. Now that I have completed a PCB I have the problem again. There is a hum generated by the chip to the input signal when I test with the multimetre although there is no voltage present. Below is the schematc with the voltages clouded. Any suggestions?

[anotherjim]

Need some debug help please. I am working on the original circuit. There were problems with oscillation when I breadbboarded the circuit. I resolved that by swapping 4069 chips. Now that I have completed a PCB I have the problem again. There is a hum generated by the chip to the input signal when I test with the multimetre although there is no voltage present. Below is the schematc with the voltages clouded. Any suggestions?

Are you using all the same components in the board that you used on the breadboard?
Just wondering if you have a faulty component other than a 4069.

[Freppo]

Need some debug help please. I am working on the original circuit. There were problems with oscillation when I breadbboarded the circuit. I resolved that by swapping 4069 chips. Now that I have completed a PCB I have the problem again. There is a hum generated by the chip to the input signal when I test with the multimetre although there is no voltage present. Below is the schematc with the voltages clouded. Any suggestions?

Sorry about the late reply.. I'm too busy too do any DIY stuff for the moment as I am moving my studio to the new house for a recording starting tomorrow
I can't see your picture of the schematic. Can you upload it again? I have built the original version on breadboard, vero and PCB without any issue. 
/ Freppo

[peterg]

Jim. I checked the components. They seem to be intact.
Freppo. Hopefully you can see the attached documents. They are yyour original schematic with my voltage readings and the pcb layout I created. It is my first attempt at using all board mount  componts
https://db.tt/8fwQTod7
https://db.tt/c39i8Lba

[anotherjim]

Voltages suggest circuit "should" be silent.
If you hook up a probe wire connected to ground, use it to "ground out" any signal at 4069 pins  8 then 4. If the noise stops with either one it should help determine the source.

I have a suspicion it could be the schmitt trigger (4069 pins 11 to jittering because it's input voltage is "half way". It shouldn't jitter. Maybe R3 needs increasing - try 33-47k.

[peterg]

Jim. Thanks for the probe/ground suggestion. I think you noticed on the marked up schematic that the circuit starts at pin 13 down to 8 and then from 1 to 6. Grounding 13 to 8 and 1 kills the noise. Grounding 2 to 6 slightly quiets it. I haven't changed R3 yet but will give it a go.

[peterg]

Thanks Jim. 47k worked.

[Freppo]

Thanks Jim. 47k worked.

I'm glad you got it sorted! That's an awesome looking pedal, and the PCB layout looks great aswell.
Nice job! I have yet to finish my build.. Too much work at the moment.

/ Freppo

[peterg]

Thanks Freppo.

[digi2t]

Voltages suggest circuit "should" be silent.
If you hook up a probe wire connected to ground, use it to "ground out" any signal at 4069 pins  8 then 4. If the noise stops with either one it should help determine the source.

I have a suspicion it could be the schmitt trigger (4069 pins 11 to jittering because it's input voltage is "half way". It shouldn't jitter. Maybe R3 needs increasing - try 33-47k.

Which one is R3? 

[peterg]

It's the 10k between the first and second inverters

[digi2t]

It's the 10k between the first and second inverters

Wait... which version are you talking about? On the "full version" I see a 10K after the second inverter.