I fixed my Wah pedal popping with a weird circuit, did I do bad?

[bobindah]

Hi folks,

Happy Christmas!

I decided to have a go a fixing the annoying popping that happens on the crybaby that has been modified for true-bypass withh a 3PDT and an LED. I have been looking on here and tried several solutions, 1M resistors to ground at the input caps etc and it would still make a pop when I turned it on. So I decided to re-work the LED circuit, I read in various places about using constant current sources to reduce the current change. Looking through my random parts draw I found one of the 78L05 voltage regulators - I knew these things can be used as current regulators also so I thought I'd give one of those a try (note I got a whole load of these for pennies so wasn't worried about frying it)  So my circuit is essentially straight out of the datasheet -

I used a 120k resistor for R1 to set the output current (it was what I had lying around and seemed to still light the LED bright enough for my uses)

The LED is the connected to the output of the regulator to ground (I put a little 1K resistor on the LED to protect it). This works a treat, to turn LED off I short the output of the circuit to ground (using the spare poles on the switch.) Now this works a treat and the little regulator doesn't get hot or anything and it seem to pretty much get rid of the pops (when used in conjunction with the 1M resistor to ground on the input cap). I am just wondering if this is a bad way of doing it, will it make chip unhappy? Have I stumbled on a fairly simple (if not a bit odd?) method to reduce LED popping in wah circuits? Or have I just got lucky and its not making any difference?

Cheers

Bob

[Earthscum]

As long as you are simply shunting across the LED to turn it off, it is a solid circuit. I'm using the same idea in a wah I'm building, although for different reasons. I need an LED to stay at a constant brightness over a range of voltages to not affect the LDR when the battery gets low. The indicator LED is gonna be normal Millenium style, since I'm using CMOS switching.
So, you did good, IMO. There's other ways of doing that, but I think you found the easiest.