multiple footswitch LEDs dimming when some are on/off

[runmikeyrun]

Hi guys.

I picked up an "antique" Peavey Roadmaster with a four button footswitch.  I added a 3mm LED to each switch and I am sending power to the footswitch via an unused pin on the DIN connector. 

I tapped 45vdc off the preamp and tried two ways to supply the LEDs...

1.  Used a current limiting resistor, however this still sends 45v to the footswitch, not ideal in case something shorts.
2.  Used a simple voltage divider to send 2.1v to the footswitch.   

In both instances, the brightness of the LEDs changes depending on how many are on/off at any given time, a problem I fully expected.  I thought to myself "self, I can't be the first person to have this issue with a stompbox."

I've done some snooping online and can't find anything really specific to solve my issue aside from small circuits using opamps and transistors, but even then are not specific enough to easily apply.

I'm hoping to find a simple solution to keep current constant despite varying loads, and simple enough to solder onto the back side of the DIN jack inside the preamp and not build out on a piece of perf.  But if that's the only way...

Thanks in advance. 

[ElectricDruid]

Can you draw us a diagram/schematic of what you've done so far? I don't know the boxes concerned, so I'm not understanding what exactly is going on. What's this DIN plug? Where do the foot switches feature in the amp schematic? How did you wire up the LEDs? (series? parallel? something else?)

[runmikeyrun]

Thanks for your reply..

Here's the first two ways I wired them, respectively, and then a possible solution.

[duck_arse]

in solution circuit, each led that turns on draws more current thru the series 5k6, thus dropping your "9V". for constant brights across any number of leds, simplest method, send the full 45V to the indicator box, use a CLR for each led.

[runmikeyrun]

Ok, that's kinda what I figured.  Just trying to avoid sending 45v to the switch box, but I might be able to find a lower voltage on the preamp PCB if I keep looking.  Thanks!

[merlinb]

In your solution diagram, replace the 1.4k resistor with a 9V zener diode.