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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoPlainText>To possibly solve my HUM induced problem in my Cry Baby Wah’s 500mH inductor<o:p></o:p></p><p class=MsoPlainText>I saw that some expensive Wah’s (like the Clyde Wah’s) use MuMetal shielded inductor<o:p></o:p></p><p class=MsoPlainText>to get rid of any surrounding EMI.<o:p></o:p></p><p class=MsoPlainText>These shielded inductors are not available from any sources..<o:p></o:p></p><p class=MsoPlainText>A company named Fulltone uses custom made inductors like these<o:p></o:p></p><p class=MsoPlainText>But would not sell any..<o:p></o:p></p><p class=MsoPlainText>BUT… last weekend I checked my parts bins and found some<o:p></o:p></p><p class=MsoPlainText>professional matching transformers the size of what I’d need.<o:p></o:p></p><p class=MsoPlainText>MICROTRAN S111-S<o:p></o:p></p><p class=MsoPlainText>I checked the actual inductance of windings and found that<o:p></o:p></p><p class=MsoPlainText><b>The primary reads 530mH (DC resistance at 60 ohms). !</b> <span style='font-family:Wingdings'>ß</span>-<o:p></o:p></p><p class=MsoPlainText>Secondary reads 140H (DC resistance at 2000 ohms).<o:p></o:p></p><p class=MsoPlainText>See the picture :<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><span style='mso-ligatures:none'><img width=451 height=338 style='width:4.6979in;height:3.5208in' id="_x0000_i1026" src="cid:image004.jpg@01DAD11E.7DF28200"></span><o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>I was wondering if using the 500mH primary inductance only,<br>leaving the secondary wires unconnected would harm the transformer.. ?<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>> On 2024-06-13 19:46, Jean-Pierre Desrochers via Synth-diy wrote:<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Hi list,<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> I have a guitar pedal board that uses 8 pedals.<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> The first pedal (receiving the guitar) is a Jim Dunlop Cry Baby Wah-Wah.<o:p></o:p></p><p class=MsoPlainText>> The following pedal is a switchable overdrive with high gain.<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Then the pedal chain goes on with 6 other pedals to a final tuner<o:p></o:p></p><p class=MsoPlainText>> that drives a guitar amplifier. Ok.<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> 4 of these pedals are powered with there separate AC supplies (9VAC,<o:p></o:p></p><p class=MsoPlainText>> 9VAC, 7.5VAC & 22VAC).<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> The other pedals are powered using 9VDC standard BOSS supplies.<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Here is my problem :<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Since the Wah-Wah is connected at the 'head' of the pedal chain and<o:p></o:p></p><p class=MsoPlainText>> uses an internal 500mH inductor in its circuit<o:p></o:p></p><p class=MsoPlainText>> it acts like the secondary of a transformer picking up 60Hz<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> from all the nearby transformers of the board.<o:p></o:p></p><p class=MsoPlainText>> I had to unsolder the inductor from the inside PCB and,<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> using short lenghts of wires connected to it … place it in the<o:p></o:p></p><p class=MsoPlainText>> Wah-Wah housing<o:p></o:p></p><p class=MsoPlainText>> at a 'specific' place and angle to get the less 60Hz pickup.<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> This is annoying..<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Now I can play with a little back ground hum when the Wah-Wah is<o:p></o:p></p><p class=MsoPlainText>> activated..<o:p></o:p></p><p class=MsoPlainText>> I was wondering if I could use an active inductor simulator circuit<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> In place of the 500mH passive inductor.. (??)<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Feasable ??<o:p></o:p></p><p class=MsoPlainText>><o:p> </o:p></p><p class=MsoPlainText>> Here is the Jim Dunlop Wah-Wah schematic : <o:p></o:p></p><p class=MsoPlainText><span style='mso-ligatures:none'><img width=845 height=464 style='width:8.802in;height:4.8333in' id="Image_x0020_2" src="cid:image001.jpg@01DAD11B.C31E3570"></span><o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>________________________________________________________<o:p></o:p></p><p class=MsoPlainText>This is the Synth-diy mailing list<o:p></o:p></p><p class=MsoPlainText>Submit email to: mailto:Synth-diy@synth-diy.org<o:p></o:p></p><p class=MsoPlainText>View archive at: https://synth-diy.org/pipermail/synth-diy/<o:p></o:p></p><p class=MsoPlainText>Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy<o:p></o:p></p><p class=MsoPlainText>Selling or trading? Use mailto:marketplace@synth-diy.org<o:p></o:p></p></div></body></html>