[sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..

Tom Wiltshire tom at electricdruid.net
Fri Jun 14 21:14:24 CEST 2024


Yes, exactly!

Tom


> On 14 Jun 2024, at 19:29, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
> 
> This schematic is a later generation… with input buffering :
>  
> <image001.png>
>  
> De : Tom Wiltshire <tom at electricdruid.net> 
> Envoyé : 14 juin 2024 13:52
> À : Jean-Pierre Desrochers <jpdesroc at oricom.ca>
> Cc : synth-diy at synth-diy.org
> Objet : Re: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement with an inductor simulator circuit.. Feasable ?? follow up..
>  
> Ok, so it's clear that yours is one of the original old-school Crybabies. Nice.
>  
> It may not sort out your current issue, but you should really try putting a buffer between the guitar and the wah. At the moment, that input transistor with its low impedance is hanging off your input signal and killing the treble, even when the wah is switched out of circuit (the switch only switches the output). That will affect the whole rest of the pedal chain.
>  
>> On 14 Jun 2024, at 15:54, Jean-Pierre Desrochers via Synth-diy <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> wrote:
>>  
>> To answer some questions :
>>  
>> ….. With so many power sources, you may be hearing a ground loop.  Never assume that the common return of multiple power sources are all the same potential.
>> There are no ground loops in my pedal board. Unselecting the Wha makes the 60hz hum completely go away.
>> And placing the inductor in a specific way in the Wha metal box almost kill completely the hum.. so no ground loop for sure.
>>  
>> ….. I'd start by looking at some of the *other* pedals to see how many could be converted to standard 9V centre-negative, and then reduce the number of transformers to reduce the noise.
>> > 4 of these pedals are powered with there separate AC supplies (9VAC, 9VAC, 7.5VAC & 22VAC).
>> > The other pedals are powered using 9VDC standard BOSS supplies
>>  
>>  
>> The 4 x AC powered pedals :
>> 2 x LINE6 modelers that could be run using 6VDC supplies (they can run on 4 x 1.5vdc C cells) eliminating two transformers..
>> 1 x Blackstar DS2 powered by 16VAC (no possible DC powering):
>> <image001.png>
>> 1 x Electro Harmonix Hum Debugger pedal powered by 7.5VAC (no schematic available)
>>  
>> The following pictures shows the real actual schematic of my Wha.
>> It’s an Italian Jen Cry Baby with a FASEL branded inductor.
>> The bottom picture shows what I’ve done to ‘place’ the inductor at the ‘sweet spot’ to get the less hum possible. Not bad..
>> But a shielded inductor could be fine (but expensives..) 
>>  
>> And again, this is not a ground loop problem..
>>  
>> <image004.jpg>
>>  
>>>  
>>>> 
>>>> 
>>>> On Jun 13, 2024, at 4:46 PM, Jean-Pierre Desrochers wrote:
>>>> > I have a guitar pedal board that uses 8 pedals.
>>>> > The first pedal (receiving the guitar) is a Jim Dunlop Cry Baby Wah-Wah.
>>>> > The following pedal is a switchable  overdrive with high gain.
>>>> > Then the pedal chain goes on with 6 other pedals to a final tuner that drives a guitar amplifier. Ok.
>>>> > 4 of these pedals are powered with there separate AC supplies (9VAC, 9VAC, 7.5VAC & 22VAC).
>>>> > The other pedals are powered using 9VDC standard BOSS supplies.
>>>> > Here is my problem :
>>>> > Since the Wah-Wah is connected at the ‘head’ of the pedal chain and uses an internal 500mH inductor in its circuit
>>>> > it acts like the secondary of a transformer picking up 60Hz
>>>> > from all the nearby transformers of the board.
>>>> > I had to unsolder the inductor from the inside PCB and,
>>>> > using short lenghts of wires connected to it … place it in the Wah-Wah housing
>>>> > at a ‘specific’ place and angle to get the less 60Hz pickup.
>>>> > This is annoying.. 
>>>> > Now I can play with a little back ground hum when the Wah-Wah is activated..
>>>> > I  was wondering if I could use an active inductor simulator circuit
>>>> > In place of the 500mH passive inductor.. (??)
>>>> > Feasable ??
>>>> 
>>>> 
>>>> 
>>>> 
>> 
>>  
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