Millennium Bypass
If anything needs a status LED it's a Wah pedal.
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The old SPDT switch had a PCB with three holes in it. What would Red Green do?
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R.G. Keen's Millennium Bypass lets you use the most reliable DPDT switch you can find for true bypass with LED. Plus the LED flickers when you plug the effect in, as a battery test. The Fulltone 3PDT switch is another option, if your are happy with it's reliability. Stewart-MacDonald 3PDT diagram.

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Bypass in position.
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Where to put the LED? If you Wah with your right foot, you lean to your left. So the LED goes on the left. It goes near the front of the pedal, so you can see it with your Silver Funkadelic Space Pants flaring around your Platform Space Booties. LEDs look dark viewed side on, the LED has to face skywards. So top left hand corner looks good. I used an LED bezel from Small Bear to hold it in place, epoxy didn't look great.