Mangler - LED wiring question

[Bret608]

Hi everyone,

So, I'm making use of the Mangler wiring diagram for a Marshall Supafuzz I built on vero and hope to box up soon. I know I only want a battery for power (to keep it old school), but I'm on the fence as far as LED/no LED.

I am a little confused by the wiring for the LED. I get how the positive leg is wired to the switch. But with the black battery lead that attaches to the LED's negative leg, does the battery lead still need to get to the board as well, and if so what's the best way to accomplish that?

Thanks,

Bret

[jkokura]

Basically, think of the two circuits independently.

- The 9V battery needs to be wired backwards compared to a typical pedal. This means, that the Black wire of the battery snap is the 'power' going into the pedal, and the Red wire is the 'ground' connecting all the rest of the circuit. So, instead of using +9V power like you do in most pedals, in this case you would be using -9V power. It's what happens if you put the positive lead of your multimeter on the negative pole of you battery, you read -9V instead of +9V, but it's still 9V of power, and ground is still 0.

- The LED needs to see the higher voltage on the long lead, the positive lead of the LED. Usually, that means you connect the long lead to the Red connection on the battery, which would be supplying +9V. However, in this case, the Red Lead is also connecting to ground, and is your 0V. The short, negative lead of the LED usually wants to see the lower voltage, which is usually 0V or Ground, but in this case it's actually -9V. So, because of this, we need to flip the LED from your typical orientation. That means, the long, positive lead of the LED will connect to your 0V, or ground setup. In this case, hooking it up to that empty pad on the switch that the Red lead of the battery also will connect to, and the ground of the circuit board connects to, and the sleeve of the jacks connect to. Then, the negative/short side of the LED, in series with a CLR resistor, connects to the same point that the lower voltage (-9V, black battery lead) connects to. You can do this at the circuit board, or at the battery, or some other way, that's up to you.

Jacob