Schadenfreude wants to tap, tap, tap

[jeffwhitfield]

Hey folks, just finished a Schadenfreude a few days ago. I think it's working...but I'm getting a weird tap from it whenever it's engaged and I'm not playing. It's at a rhythm of ever 2 seconds and appears to be coming from the CD4046BE. I switched it out and it doesn't seem to fix it. Could it be I'm using the wrong CD4046? Or maybe the 100n film caps I'm using need to be changed out? Thx in advance.

 

[Chuck D. Bones]

Have you tried a different power supply? I have a 9V PS that does not like powering 4049s running in linear mode.

A 1K resistor in series with the power (downstream from the LED) might just fix it. I think running CMOS in linear mode on 9V is a bad idea. I get less current draw and more gain by reducing the Vcc.

 

[fuzzynumbnuts]

I wonder if your "tap tap" is my "tick tick" in the Super Heterodyne Receiver:

Ticking from SuperHeterodyne Receiver

I've poked at this one several times now, boxed it up, unboxed, rinse, repeat and I'm finally throwing it out there to see if anyone has any tips. This isn't the first time this has been mentioned: https://forum.pedalpcb.com/threads/mini-heterodyne-receiver.462/post-2722 The ticking only...

forum.pedalpcb.com

Does it sound like this?

https://soundcloud.com/user-74207647%2Ftick%2Fs-q25YU2uUSou

Mine seems to be coming from IC6 which is a 4046 as well. I'm sure there are a boat load of other reasons why this could be occurring, but I've been watching this thread to see if you came to any conclusions. I too switched out the chip for one I bought directly from TI and the problem still existed. When I last pulled it off the shelf I feel like for a brief moment the noise went away when I unplugged the input (this isn't the case so I must have been delirious at the time), so I threw a shielded input cable on it just for the hell of it and no dice. The only thing that I've found that "fixed" it was knocking the voltage down to 8v.

!!!!!! I think I solved the constant tick on the super heterodyne receiver. I put a 1m ohm resistor from pin 7 of the cd4046 to ground. I had the same ticking and now it's completely gone, and no noticeable change to the pedal! Maybe someone smarter can explain why this worked, I was messing around with a putting it at pin 9 to see if maybe it was something in the VCO path, but my hand slipped and discovered this!