Cool Solution, or Old Man's Folly?

MrWookiee

Country Gent
Jun 17, 2020
1,253
SoCal, USA
I was disappointed that my Supro Blues King footswitch didn't have status indicators. The amp doesn't either but at least you can look at the toggle switches' positions. I wrongly figured that adding a couple of LEDs would be an easy deal. I say wrongly because the power to the footswitches is -13.8vdc and -15.2vdc on the Gain and Boost switches, respectively. Furthermore, the Gain is ON when the switch is open (not shorted to ground) while Boost is OFF when not shorted to ground. When using 12V LEDs with the proper resistor values added the darned functions wouldn't work, even though the LEDs switched on and off. Also, the amp's functionality with resistors but no LEDs worked fine. The saving grace was that the original switches each had 2 rows of 3 pins that were isolated electrically with one row on each switch being unused. I eventually decided to add a 9vdc jack (standard pedal power) and switch power to the two LEDs independent of each other and not affecting the original circuitry in any way. It came out pretty well, I think, and isn't overly bright since It is 9v into 12v LEDs. I forgot to include a fuse on the 9v power though.
 

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Last edited:

DennisC

Country Gent
May 11, 2017
1,327
Germany
Very nice, and very useful!

I don't think spending more time than most would on some detail like this is a mistake, but it is ... cool.
 

Henry

I Bleed Orange
Apr 9, 2014
18,344
Petaluma
Awesome. Yea pretty lame that the switch doesn't have lights. My 2 amps have switches with lights and the lights are powered through the cable to the amp so no separate power needed.
 

ruger9

Country Gent
Nov 1, 2008
3,455
NJ
:cool: I'm willing to take a risk with my own stuff now and then but wouldn't have the nerve to try it on someone else's! :D

It's nice, clean work!

Awesome. Yea pretty lame that the switch doesn't have lights. My 2 amps have switches with lights and the lights are powered through the cable to the amp so no separate power needed.

Most Fender footswitches are also light-less; a few people on eBay/reverb make a pedal like in the OP with LEDs. I think they're $50? The 2 amps I have that have reverb and tremolo aren't gig amps for me, so it's not really a big deal. (Supro Tremoverb and Fender PRRI)
 

Ricochet

Senior Gretsch-Talker
Nov 13, 2009
21,245
Monkey Island
I was going to use green and blue LEDs - green for Gain and blue for Boost - but they were what my sons would call "stupid bright"; they were blinding even at 9v, so I went with the two least-bright colors I had.

Why not tame the brightness with a couple of resistors?
 

MrWookiee

Country Gent
Jun 17, 2020
1,253
SoCal, USA
Why not tame the brightness with a couple of resistors?
The yellow and red are really not as bright as they appear in the photos, though they are bright enough. Honestly, I went through a frustrating few weeks of intermittent trial-and-error in figuring out how to make the mod work. After doing some testing I thought I'd found the solution so I drilled the LED holes, only to find that the amp wouldn't function when the LEDs were in the loop ("Oh, great... it doesn't work AND I've ruined the cover... <filth flarn filth>").
I really wanted to power the LEDs via the footswitch cable; maybe having to reverse the LEDs due to the negative DC voltages caused them to block the sensing current the amp needed(?). There probably is a way to do it without the 9v power jack but I'm a software guy who can build kits, not an electrical engineer. By the time I found a combination that worked I was over it. :p So I'm happy with the result and the learning experience but there was far more drama than one would expect for a mod that should have taken 20-30 minutes. o_O
 

Ricochet

Senior Gretsch-Talker
Nov 13, 2009
21,245
Monkey Island
The yellow and red are really not as bright as they appear in the photos, though they are bright enough. Honestly, I went through a frustrating few weeks of intermittent trial-and-error in figuring out how to make the mod work. After doing some testing I thought I'd found the solution so I drilled the LED holes, only to find that the amp wouldn't function when the LEDs were in the loop ("Oh, great... it doesn't work AND I've ruined the cover... <filth flarn filth>").
I really wanted to power the LEDs via the footswitch cable; maybe having to reverse the LEDs due to the negative DC voltages caused them to block the sensing current the amp needed(?). There probably is a way to do it without the 9v power jack but I'm a software guy who can build kits, not an electrical engineer. By the time I found a combination that worked I was over it. :p So I'm happy with the result and the learning experience but there was far more drama than one would expect for a mod that should have taken 20-30 minutes. o_O

It all sounds too familiar. :rolleyes:
I’m no EE either, but you can not reverse LEDs. They just work one way, Anode+, cathode-. You will have to find a way to reverse everything else.
 


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