Footswitches for Clean Boost/Fat Option
Here are some footswitches that have a TRS (tip, ring, sleeve) or stereo plug and two switches. Some have LEDs, but they won’t light because the Blues Junior senses the position of the switches by sending a -15 volt signal through the switches. When it’s grounded by the appropriate switch, the Fat or Clean Boost turns on. It’s possible that you could rewire one of the LED-equipped pedals by reversing the polarity of the LEDs and putting them in series with the switch. It may require a dropping resistor to prevent damage to the LED and too large a dropping resistor may prevent the amp from sensing the switch position.
I haven’t tested this modification, however, so you’re on your own.
You might be able to rewire the LEDs on this one by putting them in series with the switches, positive side to ground:
Here’s an inexpensive footswitch with a built-in 9V battery, so the LEDs work independently of the amp. Looks like a winner, reasonably priced: