How to get LEDs to turn off instantly when powering down?

[Philtre]

When I turn off a shop-bought pedal at the mains the LED turns off instantly (powered by a power supply, not battery). If I do the same on one of my builds the LED gradually fades away as I assume there is some residual current in the power supply. So, how do manufacturers achieve the instant-off LED when turning off the power supply?

[matmosphere]

Mine always go off instantaneously. How long is the latency?

Is the pedal you built true bypass or buffered? How do you have things wired?

[Philtre]

Fades out over a couple of seconds.

I'm using a GigRig modular power supply.

True Bypass.

LED wired to the stomp via a 2.2k CLR and then to positive as per this layout - http://1.bp.blogspot.com/-k5Sh68yVU18/TzGRFKbiALI/AAAAAAAAAlk/CbfaaduUjYQ/s1600/!Offboard+wiring.png

Bear in mind I'm not talking about pressing the stomp switch, I mean when the pedal is on and then I power down at the mains / power supply.

[somnif]

Might be the filter cap discharging through the LED?

I don't know what style of circuit your commercial pedal is, but it may use a different type of set up to make the LED light than the brute force "just switch the ground" method we use.

[matmosphere]

What you are talking about doesn't have anything to do with your pedal, it's happening while your power supply is discharging itself. Mine do the same thing. It's not anything to worry about It won't hurt a thing.

Just a guess but the commercial pedals are probably using a relay bypass, and just behave differently when the power is cut.

http://www.coda-effects.com/2016/04/relay-bypass-conception-and-relay.html?m=1

You could change the value of the CLR to something a little larger and see if that changes it. I generally use 4k7.

[Philtre]

Thanks for replies. I'm not worried about it, just curious.