Vintage Rat problem

[eltigre1985]

Hi, I'm new here and was hoping someone could tell me how to add an LED into my "Vintage Rat" pedal. I know its a very easy mod, but I'm a complete novice.

The switch is 3pdt with the middle row completely unused. I checked all the contacts with a voltmeter and soldered the LED circuit into the only pin which had a polarity change. My pedal is now a third of the volume when switched on, and the LED is always on (bright when the switch is off, dull when on).

Help!

[Sic]

not my picture btw, just did a quick search in the site. it is an excelent example

Aron posted both of these pictures, all credit to him

and here

[eltigre1985]

Thanks. I'd seen that diagram, but the wiring doesn't correpond with the way the switch is currently wired. Is there any way to add an LED indicator without changing any of the existing wiring?

[smoguzbenjamin]

The middle row is completely unused, right? Then use your DMM to check in which state the effect is on, and wire the LED accordingly

See, checking a switch for potentials won't work right and you might get wierd data.  Could you draw up a diagram for how the switch is wired?

[amz-fx]

The switch is 3pdt with the middle row completely unused.

So you can use that row of contacts to control the LED...

Set your meter set to ohms and find which outside lug of the middle row is connected to the center lug on the middle row when the effect is on.  That is the pair of contacts in the middle row that you want to use.

Connect a wire to a source of +9v on the Rat pcb and run the wire to the anode of the LED.  Solder a 1k resistor to the other leg (cathode)  of the  LED  then a wire from the opposite end of that 1k resistor to the outside lug of the middle row on the switch.  Run a wire from the middle lug of the middle row of the switch to ground.

So you have a series connection from +9v to LED to resistor to switch, through switch to ground.  All new switch connections are on the middle row of contacts only.

regards, Jack

[eltigre1985]

Thanks for the info! I'll give it a go tomorow.