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Adding LED "Power On" lights to pedals and amps

Hi, I am making a few effects pedals for a friend, and also a kit form preamp for a home stereo system. The pedals are battery powered and the preamp uses an AC current. I would like to add power on style LEDs so people can tell if the thing is switched on or not. Can someone suggest a way of doing this for both power types or either one? Do you need details of circuits and the like, or is it a simple process. Let me know what info you need.
All the best from Bill. :D

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Permalink Reply by Blues Frog on June 24, 2015 at 3:15pm

Depends on your circuit and what you want to show as powered. If you're trying to show the AC circuit, put an AC led in series with the circuit on the powered side.

If trying to use the DC side(battery) wire in the DC circuit.

Here's an discussion on LEDs on this site http://www.cigarboxnation.com/forum/topics/led-hookup

Make sure your LED is rated for the type of voltage you are wiring into.

Hopes this helps.

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Permalink Reply by John Sawyer on June 24, 2015 at 4:14pm

Most pedals run on 9v, even when AC powered. The trick is to find a clean DC source, or one that is live when the pedal is "HOT".

LEDs can vary in their voltage requirements, but most have a voltage drop of 1.7 to 2.1v, and blues in the 3.4v range... ok.. back up...

Get some cheap red or green LEDs. do NOT get the clear ones.. those are high-brightness LEDs, and it'll be like having a flashlight...

You'll need 680 ohm resistor. That'll work with red, yellow, or green led's and be close enough... you won't be running the full output of the LED, but it will be bright enough to see..

On the LED, there are 2 leads... The longer one goes to the Positive (+) power, the other to ground. Somewhere you will need the resistor, and it really makes no difference which leg you solder it to.

Make sure you put some heat shrink over the exposed wires to avoid shorting something out.

If you post a Pic of the pedal (opened) I'm sure we can identify where to get power from. The best bet is to use a digital voltmeter.

John

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Permalink Reply by Bufo Bill on June 25, 2015 at 7:08am

Thanks for your help guys. John, the pedal I am doing first is in kit form and currently is a little bag full of bits. Shall I get back to you when I have assembled it, or can you tell where to place the LED from a circuit diagram?

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Permalink Reply by John Sawyer on June 25, 2015 at 8:50am

Circuit diagram would be great!

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Permalink Reply by Bufo Bill on June 25, 2015 at 9:32am

Hi John, the link below takes you to the product I have and if you scroll down there is a PDF to download, and there is a schematic in there . . . Don't you love it when websites are this accessible - not!
http://shop.pedalparts.co.uk/AstroTone_Fuzz_-_Sam_Ash_Fuzzz_Box/p84...