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

[rburnett at richieburnett.co.uk]

If it's an open core inductor then putting high-permeability shielding 
material close to it will likely increase it's inductance.  (If it was a 
closed core design with no air-gap in the magnetic path, then it 
probably wouldn't be sensitive to external magnetic fields anyway.  The 
bigger the air-gap the more susceptibility to external magnetic fields, 
but the air gap also stabilises the inductance and makes it more 
resistant to saturation.)

You could always try shielding the offending mains transformer that is 
the *source* of the interference, rather than tackling it at the 
destination end.  Aren't toroidal mains transformers supposed to be 
better in this respect?

-Richie,



On 2024-06-14 17:37, Jean-Pierre Desrochers via Synth-diy wrote:
> After reading some forums, it seems that shielding an inductor
> 
> Will change its caracteristics a lot..
> 
> If so, not acceptable for me..
> 
> De : Synth-diy <synth-diy-bounces at synth-diy.org> De la part de Mike
> Beauchamp
> Envoyé : 13 juin 2024 20:43
> À : synth-diy at synth-diy.org
> Objet : Re: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor
> replacement with an inductor simulator circuit.. Feasable ??
> 
> Maybe try some magnetic shielding. I've used this product in the past
> with good success:
> 
> https://www.amazon.com/WOREMOR-Magnetic-Shielding-Amorphous-Alternating/dp/B08JKVMRB7
> 
> I've used this stuff to shield 60hz getting into reverb tanks, and
> it's actually worked better than another product called mu-metal - at
> least in my testing. The shit is razor sharp though, watch out.
> 
> If you're confident the inductor is picking up the interference, you
> can build a little shield around it it using this stuff. I'd even
> desolder the inductor so I can place shielding on the bottom as well.
> You can also use it to place shields around the AC supplies as well.
> 
> Mike
> 
> On 2024-06-13 19:46, Jean-Pierre Desrochers via Synth-diy wrote:
> 
>> Hi list,
>> 
>> 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 ??
>> 
>> Here is the  Jim Dunlop Wah-Wah schematic :
>> 
>> ________________________________________________________
>> 
>> This is the Synth-diy mailing list
>> 
>> Submit email to: Synth-diy at synth-diy.org
>> 
>> View archive at: https://synth-diy.org/pipermail/synth-diy/
>> 
>> Check your settings at:
>> https://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> Selling or trading? Use marketplace at synth-diy.org
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org
> View archive at: https://synth-diy.org/pipermail/synth-diy/
> Check your settings at: 
> https://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org