[sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement .. Found a small professional MuMetal shielded matching transformer @ 530mH on primary..

[Jean-Pierre Desrochers]

To possibly solve my HUM induced problem in my Cry Baby Wah’s 500mH inductor

I saw that some expensive  Wah’s  (like the Clyde Wah’s) use MuMetal shielded inductor

to get rid of any surrounding EMI.

These shielded inductors are not available from any sources..

A company named Fulltone uses custom made inductors like these

But would not sell any..

BUT… last weekend  I checked my parts bins and found some

professional matching transformers the size of what I’d need.

MICROTRAN S111-S

I checked the actual inductance of windings and found that

The primary reads 530mH (DC resistance at 60 ohms). ! <---

Secondary reads 140H (DC resistance at 2000 ohms).

See the picture :

 



 

I was wondering if using the 500mH primary inductance only,
leaving the secondary wires unconnected would harm the transformer.. ?

 

 

 

 

 

> 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 : 



 

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