Pop and click and led resistor

[Kipper4]

i've seen several time folk say put a resistor in to stop those pops when you bypass and kick the effect in.
What resistors are best for this and how is it done?

Also i've seen folks say put a resistor on the anode of leds. My dumb question What resistor to use for this as i figured it would make goos stock item. Value and wattage pls.

[Kesh]

1M to 2M2 from input to ground.

LEDs have to have a resistor somewhere to stop it burning out, doesn't matter if anode or cathode. For 9V battery and a normal red LED that can take 20mA you want AT LEAST 390 ohms, but this will wear down your battery a lot, so a lot of pedals go way higher, up to 4k7. You don't lose as much brightness as you'd expect.

You can combine 2 resistors and a cap to prevent LED pop, too.

[Pyr0]

The less current a LED draws, the less likely it will cause a pop. I tend to use anything from 3k to 5.1k for regular leds, and up to 20k for the clear bright LEDs. They tend not to be so blinding too - no need to have them glow like a beacon. 

[snarblinge]

look here

http://www.muzique.com/lab/led.htm


this is the method I have used, bumped the cap to 33uF and it has solved all my popping issues.

[Kipper4]

brilliant stuff guys
thanks
Another snippet for my little note book.

[R.G.]

As background for understanding why things happen, which is important to me, clicks and pops are always symptoms of sudden edges in the signal voltage. Since most pedal electronics have no ground noise rejection whatsoever, any ground noise is coupled right in too.

So anything that makes the ground reference move will also cause ticks and pops.

The LED click issue is a result of ground current issues. No wire is a true short circuit. They are all resistors, even if low-value ones. When you funnel current through a resistor, a voltage develops across it. In a pedal, an indicator LED is often the single largest current user, and it's switched HARD on and off. That sudden on and off current causes a resulting on and off small voltage in the ground wires that carry it.

If the ground wire carrying the LED current is the same wire carrying the input stage ground reference voltage, the input stage amplifies the small change in voltage.

You would think that this would be avoided as a bad way to wire things. Sadly, it's not. On most pedals the use of the input jack as a switch to switch power from the battery and/or adapter puts 100% of the whole pedal's current flowing on the same wire as the input signal. What is surprising is that this is not more of a problem than gets mentioned. Chalk that up to general luck.

Moving the LED return wire may remove the problem. Changing the way input power is switched may remove the problem.

There is another way to remove the problem, and that is what the illustrated snippet does. The human ear cannot hear sounds below some minimal frequency. Another way of saying that is the ear is blind to signals moving slowly enough. The illustrated circuit slows down the sudden voltage applied to the LED, and so slows down the speed of any suddenly generated ground currents. They're still there, they just move slowly enough to be in- or less-audible.

[Kipper4]

Thanks for the concise and easy to understand explanation RG.
Its always good to understand whats going on.
I'm just starting my journey into pedal building. I love it i'm now on my third circuit.
This time I'm attempting the AMZ muffmaster.
Previous builds treble booster,bipolar booster, and a deacy amp kit build.
Rest assured i will be asking lots more questions that you will have answered a million times already.