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

[Mike Bryant]

It won't harm the transformer.   What you may find is the resonance is too peaky so if so put some resistance (by trial and error to get the right sound) across the secondary.


________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Jean-Pierre Desrochers via Synth-diy <synth-diy at synth-diy.org>
Sent: 08 July 2024 15:06
To: Synth-diy at synth-diy.org <Synth-diy at synth-diy.org>
Subject: [sdiy] Jim Dunlop Cry Baby Wah-Wah.. 500mH inductor replacement .. Found a small professional MuMetal shielded matching transformer @ 530mH on primary..


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 :



[cid:image004.jpg at 01DAD11E.7DF28200]



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 :

[cid:image001.jpg at 01DAD11B.C31E3570]



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