Author Topic: Yet Another Pull Down Resistor Question  (Read 1295 times)

effectsbay

Yet Another Pull Down Resistor Question
« on: March 22, 2010, 08:36:08 PM »
Sorry guys, but I have to ask. I've been digging, reading, experimenting, but I'm still having problems with with pops in my pedals. I've tried adding pull down resistors (1M from input to ground and 1M from output to ground). I've also tried adding caps in there.. but the pop is always the same.. never changing. I've avoided the resistor from tip to ground lug though (I've read that's not the best since your signal would be going through that.. even though the circuit is bypassed, so I'm opting to not go this route). The thing that is weird.. all of these attempts did not affect the pop in the slightest. I feel like I'm barking up the wrong tree.

I was initially getting this with a MOSFET clean boost, but my latest project, a buffer pedal does it as well. I also thought I'd try an experiment with the the PCB boards for the 3PDT switches (claims to help with pops) but no go. I guess my question is this. How do I begin tracking down the pop. Is there anything I can measure, etc? I feel like I'm blindly sticking resistors around, etc. and not making any progress.

I definitely feel this is a result of the caps that are leaking. It seems like the pops build up, and are mostly heard (if not always) when the circuit is bypassed. My MOSFET boost, I even added 10M resistors at input/output to ground on the circuit board.. and made no change. I started to suspect my switch (the reason why I tried the PCB). I'm at a loss and want to learn and get this fixed. Any suggestions is greatly appreciated.

hank

rpjones

Re: Yet Another Pull Down Resistor Question
« Reply #1 on: March 22, 2010, 11:02:56 PM »
I too had a serious popping problem with my mosfet booster, I even tried the fix presented in this AMZ article:

http://www.muzique.com/lab/led.htm

but the pop was still there. Finally, I just wired up the 3PDT switch to ground the input when bypassed and presto, no more pop!

effectsbay

Re: Yet Another Pull Down Resistor Question
« Reply #2 on: March 22, 2010, 11:10:52 PM »
I too had a serious popping problem with my mosfet booster, I even tried the fix presented in this AMZ article:

http://www.muzique.com/lab/led.htm

but the pop was still there. Finally, I just wired up the 3PDT switch to ground the input when bypassed and presto, no more pop!

Hmm.. that's interesting. I keep thinking it's with the switch portion, since the changes I made to the board never affects the pop. Do you have a diagram of that switch you used? I think I've done 3 different true bypass switches with the MOSFET.. I want to say that one of them had the ground jumped to the input on 'off', but I might be wrong... digging through my notes now.

Thanks!
hank

rpjones

Re: Yet Another Pull Down Resistor Question
« Reply #3 on: March 22, 2010, 11:54:31 PM »
I used this, diagram number 5:

http://www.tonepad.com/getFile.asp?id=76

effectsbay

Re: Yet Another Pull Down Resistor Question
« Reply #4 on: March 23, 2010, 10:33:17 AM »
This is great. I think I've done this one though.. but I'll try it again, I'm making another buffer pedal in the next few days, and I'll give this one a shot. I might bust out the MOSFET and redo that as well.

Thanks!
hank

effectsbay

Re: Yet Another Pull Down Resistor Question
« Reply #5 on: March 23, 2010, 10:42:49 AM »
I actually take that back. I just cracked open the MOSFET boost I put together and the 3PDT switch is following this wiring scheme? Only difference, is the input jack. In my MOSFET I have battery snap negative going to sleeve, and the board/center lug ground is going to ring? This diagram is the opposite? It shows the board/center lug grounds going to sleeve and the battery going to ring? My MOSFET doesn't have 9VDC Jack. Would that make a difference?

Thanks!
hank