not the ususal LED indicator question!

[delbowski]

hi...

i'm trying to go about a project making a true bypass strip with four loops in it (4 switches).  i also want to make it so that i can insert other pedals (already true bypass) into the signal chain between each switch of the bypass strip.  i have that all figured out, but i would like to make it so that when i insert other pedals into the chain an LED will light up to show where in the chain i have a pedal inserted.  so, how can i wire this so that the an LED will light up when i plug a cable into a jack?  i'm using NC mono jacks for this part of the design as well as an adaptor as opposed to battery.  this seems really simple, so hopefully im overlooking something easy.  i want to plug a cable into the 1/4" jack and make it turn an LED on.  my searches have come up empty... any help would be great!  i can always use a humbling experience...

[R.G.]

Oh, c'mon - that's an easy one.

You make one jack of each loop be a stereo jack, then hook and LED/resistor up from +9V to the ring terminal. That way a mono jack plugged in shorts the LED to ground and makes the LED come on.

That's the first order version. It will make a HORRIBLE pop as you put in a plug if you do this live. The second order version cold switches the LED by using a PNP transistor to turn on power to the LED/resistor by using the stereo jack trick to ground a 10K resistor on the base of the PNP. It still pops, but not as badly.

There are other ways as well, including jacks with switches.

[delbowski]

thanks R.G.

i'll consider myself humbled...  if overlooking the obvious paid any money, i'd be a millionaire!  thanks!

del

[R.G.]

Humbled? Not at all - you'd have figured it out, and in not very long. That's why I said "Oh c'mon...".

[delbowski]

yeah i think i would have gotten it sooner or later.  i knew that i had to get the LED to ground when i plugged the 1/4" in, but i was stuck in the mindframe of "mono jack, mono jack, mono jack!"  i think i'm gonna use your first suggestion, as i will have everything set up before i turn my amp on.  thanks again!  i really appreciate it. 

del