LED makes my orange squeezer pop

[charbot]

I built a orange squeezer using the schematic and layout from GGG. http://www.generalguitargadgets.com/index.php?option=content&task=view&id=47&Itemid=79

I used a blue 3dpt but skipped the indicator LED because I was impatient.  I sounds good but when I finally got around to hooking it up I noticed that it causes a nasty "pop" when the effect/ LED is being turned back on.   It is not the switch and I have already tried   1m pull down resistors as well as a number of Led and in line resistor combos.  the only thing that works (sorta) is to increase the in line resistance  30 times  :
10k replacing the 300   ohms required by my led....
anyway that make the pop barely audible, but the LED is barely visable.   
I guess that when the LED comes on, it is either overloading or draining the power to the circut. I suspect that it is the latter because the pull down resistors would prevent any kind of overload... right?
I'm learn' as I go.

any suggestions?

[R.G.]

You have already answered your own question - you just don't know it.

The problem is, as you say, the sudden current transition when you turn the LED on. The smaller that transition, the less the pop. I don't have the wiring diagram here, but it could be a result of the LED current and the signal ground sharing a wire; it could be a radiated pop into a high impedance point. The problem with most of this kind of thing is the wiring.

The fix? Rework the wiring to have the LED current not share any wires with the circuit, expecially the battery - wire. Band aid fixes that might be good enough include using superbright LEDs and low currents and splitting the LED load resistor and inserting a capacitor so the LED turns on slowly.

[moosapotamus]

You could also try putting a 10uF cap at the junction of the LED and the in-line (current limiting) resistor, with - leg of the cap to ground.

~ Charlie

[charbot]

Thanks!   I guess Ijust didnt expect this... all of my othe pedals are wired similarly and this is the one that pops.  And now if  I may ask another obvious question....
R.G., when you say "Rework the wiring to have the LED current not share any wires with the circuit, expecially the battery - wire." do you mean that the LED needs a seperate battery? 

I just found the pop filter thred above this and am going to check it out. 

[charbot]

I also forgot to mention the I omitted the external power jack and just attached the led wire to the board where the +9v is attached.   I guess this is where the wireing problem lies.

[Mark Hammer]

I joke with my wife that many days there is no reason to come to work before 4:30, because everything happens at 4:30 as managers come back from meetings and dump all the emergencies in our laps.  Life's like that.  Everything is running smoothly, and then BOOM, an emergency disrupts and derails all the things you're working on (one of the many reasons why big perfboard projects are a dangerous thing to start unless you have a LOT of free time).

Circuits are like that too.  The battery is just humming along providing every part of the circuit with the current it needs, and then BOOM, some other part of the circuit insists on hogging a lot of current in a short burst.  That is what you hear as a ticking in pedals with an LFO.  That is also what you hear when the LED makes a sudden demand for lots of current.  You will note that when the current-limiting resistor is increased (which means much less current from the battery can be diverted to the LED), the popping disappears.

If life gave you a "freeze" button, so that when emergencies popped up, you could stop everything, tie up loose ends on what you were doing, then "un-freeze" to deal with the emergency, life would be grand, wouldn't it.

Well, life may not be like that, but circuits CAN be.  The suggested cap that essentially goes in parallel with the LED provides two functions.  First, it slows down the current-swallowing of the LED, or rather spreads it out a bit, by introducing some lag. You will note the similarity between the RC combination of that added cap and the current limiting resistor, and the circuits often discussed in autowahs that are intended to slow down the attack time of filter sweeps.  Same principle. 

And, similar to those very circuits, the added cap provides a small reservoir of current that takes a moment to drain off.  You probably won't notice that aspect as providing any great advantage for depopping status LEDs, but when it comes to deticking LFOs, that little reservoir also tends to reduce subsequent current demands upon the next quick voltage swing that the LFO undergoes, which is a big part of reducing audible ticking.

The principle is pretty simple, actually: whenever you suspect that a part of the circuit will make any sudden excessive (relative to everything else) current demands, it is a good idea to "decouple" the power supply line to that device/segment so that it will not affect other parts of the circuit simply on the basis of what it needs from the battery.

[charbot]

Thanks for the knowledge guys.

I messed around today and so far the most effective remedy Ive found is to split load resistance  with a 220uf to ground in between. 
I have not noticed any delay or flicker when the LED turns on or off.
Also Ive found that the cap need its own wire to the circut board ground, not just placed in parallel with the LED and ground through the foot switch.   Now there is no pop but rather a void or hiccup in the power,   where the sound drops fro a moment.
this is only noticable when I switch while still the guitar is still making sound and is still less bothersome and intrusive than the pop.

Am I wrong in assuming that the the reason that Ive run across this problem with the squeezer and not an octave   fuzz face,  or Dr Quack, (for example)  is that the squeezer draws a little more power than those other effects and is thus the drain from the LED is more noticable?  ... and this same thing is going on with any pedal/effect with a footswitch/ indicator LED that is wired similarly...eg. nearly every effect out there...

I really appreciate the suggestions guys.  thanks for your time.