Popping noise on Orange Squeezer.

[glesconz]

Hi, I just finished my very first project, an Orange Squeezer compressor...fired it up, didnt work - flat 9v batt !!!!    But once i fixed that, she powered itnto life and worked beautifully, except for switch popping. I have a pulldown resistor (2.2M) at the input, just before the 0.047 cap. I see on some circuits there is a pulldown resistor of 4.7 M and other circuits none at all. I read most people use a 1M resistor in their circuits.
Im using tantalum caps, not electrolytics.
I dont have a pulldown resistor at the output as the circuit has a 10k volume pot there. I read you dont need one there if there is a pot there....should I put one in after the 1.5k to ground?

http://www.geofex.com/FX_images/orgsqz.gif

Thanks for your help,
Glenn

[PRR]

Check polarity on the electrolytics (in this case, all the 4.7uF caps).

In R.G.'s notation, the curved electrode is the Negative.

[glesconz]

Hi, thanks, no all polaritys are good. I'll try taking the LED off the 3pdt switch and see what happens...assuming it still does it ill change the wiring on the switch. At the moment I have

1 2 3
4 5 6
7 8 9

where 456 are the common terminals (4 connects with 1 or 7 when switched etc).

I have it

1 - 2 Jumper
3      NC
4      Input Jack
5      Output Jack
6      Ground
7      Effect Input
8      Effect Output
9      -ve lead of LED

Thanks,
Glenn

[spargo]

I just had this same problem with a pedal I built with pulldown resistors - the problem was in how the switch was wired.  The input of the board should be connected to ground when bypassed.  This fixed it for me.

I believe if you simply jumper 3 and 7 in your switch that should do it.  This grounds the input while in bypass and magically took care of popping on the pedal for me.  Good luck!

[glesconz]

Thanks Spargo, that seems to have helped alot...theres alot of different ways to wire a 3pdt switch shown on the net!!! When you wind the vol up on the compressor the noise is still there though, is a dropdown resistor needed on the FX output, in this case the number 2 contact on the pot, to ground? Contact number 1 is already grounded.

Thanks,
Glenn

[spargo]

Glenn, I'm no expert (about to start only my 3rd pedal  ), but my understanding is that if the circuit ends with a volume pot then you don't need a pulldown resistor at the output - the pot serves this purpose.  And there appears to already be a pulldown resistor at the input.  I have also heard (especially if you are using superbright LEDs which I love - 270ohm resistors  ) that you may not be able to COMPLETELY get rid of the popping.  If it is faint with the volume turned up high, that may be as good as you'll get.  But if you're using a breadboard and it isn't much trouble to try it, I'd try a 1M resistor right before the output anyway, it couldn't hurt to see what it does.  The exact value isn't important, but I think around 1-2M is good.

My main concern with pops is if they are large, specifically if the pedal is being switched while my delay is on, in which case you get pop pop pop pop pop......

Also, as a side note you mentioned tantalums.  Are you using tantalums for the 4.7uF caps or for the others?  I recently had a bad experience with tantalums and determined they are BAD to put in the place of a film cap that is non-polarized.  Also, they are generally noisier in audio circuits so you may take that into consideration.

[glesconz]

Hi spargo, thanks. The tantalums were for the 4.7uF's, the others were film. Ill try a 1M and see. Once its all boxed up and star ground wired and sheild cabled instead of the hookup wire Im using for everything it may help too....

Cheers,
Glenn