Amp-Powered Foot-switch LEDs

[tdvt]

I am getting ready to finish up a Hoffman AB673 for my son & he would like LEDs added to the foot-switch. I am thinking of adding a 3rd conductor(+shield) to the foot-switch cable & tapping off the heater supply to power the LEDs. Then just use DTDT's to switch the LEDs to the common ground. Would filtering the LED tap off the heater AC in the amp be a good idea? I am also using an LED for a pilot light, fitted to a standard jewel mounting so I could use the same tap for both.

I was planning to hard-wire the switches anyway so no connector issues.

Any caveats or something I'm not considering? Seems as though foot-switch cables can generate noise/hum, so I thought I'd ask.

[phsyconoodler]

You need to rectify any supply to make it DC power first.Then use a relay to change the LED power on or off.You will need to change the footswitches to DPDT switches to separate the actual function from the LED switching.You don't want to mix the two up.
then you need to use another twp conductor cable to the footswitch to feed the LED's.So you will need a 4 conductor cable.
  It would be better to add a battery inside the footswitch and two DPDT switches and do it inside the foot switch itself.

[Geezer]

You don't mention it, so.....are you using relays, or are you just planning on running the signal all the way out to the footswitches, then back to the amp?

Relays are the way to go, and there is probably going to be enough voltage on the wires going out to the footswitches to run the LEDs.

I use the Weber relay boards & run the LEDs off the voltage present @ the footswitches.

G

EDIT: I'm seeing AB763 now   , so I suppose you're just footswitching the normal reverb & trem, (correct?)

Personally, I would expect noise introduced into the circuit by running 6.3v alongside the other conductors.

Maybe a 9v battery in the footswitch box itself would be the easiest(?)....def the quietest. Don't forget the CLR's (current limiting resistors)

EDIT #2....I see 'noodler & I are sort'a on the same page here......

[phsyconoodler]

Yeah we are on the same page.Do it inside the footswitch.Use mini-switches and two LED dropping resistors.Easy as pie.

[TIMBO]

DID someone mention PIE!!!!!

[tdvt]

Thanks for the feedback.

I re-did a Peavey footswitch for a friend a few years back with a battery & DPDTs, he may still have the same battery in there for all I know.

The only down side with that set-up is remembering to make sure the LEDS are off when stowing the amp since they function independent of amplifier power. Any ideas to deal with that?

I was worried about introducing noise using amp power, that would not be a good thing.

[Willabe]

If the foot switches are for reverb and vibrato, you don't need an LED to tell if their on or off.

It might look cool but, music is in the ears not the eyes.


                       Brad     

[phsyconoodler]

Quote:"Any ideas to deal with that?"

Sure,take out the battery.

[cbass]

Could a person conect the battery groud to the sheilding? Then when you unplug the footswitch the battery will be disconected.

[Geezer]

Could a person connect the battery groud to the sheilding? Then when you unplug the footswitch the battery will be disconected.

Yes, do it like they do on stompboxes....use a TRS (Tip/Ring/Sleeve) jack, and have the "Ring" connection on the jack make the ground connection when the  cord is plugged in, and the connection is broken when the cord is unplugged.

Switchcraft 12B is the one, found on this page of Doug's catalog>>>
http://www.hoffmanamps.com/MyStore/catalog/parts8.htm

G