# quick LED question



## ezcomes (Jul 28, 2008)

i want to put some LED's into my amp head...can i try into the power at the jewel and run it from there...so when the jewel comes on, the LED would come on?

curious is all


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## greco (Jul 15, 2007)

What make and model of amp do you have?

Do you know the voltage at the jewel/pilot light?

How many LED's are you considering? 

Cheers

Dave


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## ezcomes (Jul 28, 2008)

18W marshall kit
not yet...once i build it i will
somewhere between 4...and buying a string of these:
QKits Electronic Kits: LDB1-HS3018AR, Flex LED Strip Module - Red - 18 LEDs


i want to do either like what i've done here with a 9V battery











or make a plexiglass front panel and make a H&K style front panel a la:


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## greco (Jul 15, 2007)

I am not an amp tech...but these are some thoughts:

I *think* you *might* have 6.3 *VAC* from the power transformer to the pilot light. Any chance of a link to the schematic of the kit you are going to build?

These are the specs from the website Re: the LED flexible strip module you are considering:
[h=1]Specifications[/h]

color: red
LED quantity: 18 pcs
power consumption: 2.16W
*power supply: 12VDC*
current per LED: 18mA ± 2mA
*min. cut length: 3 LEDs*
life span: ± 70 000h
dimensions: 5/8" x 12 1/8"

The LED's require a power supply of 12 *VDC* (possibly less if you aren't going to use all 18 LED's).
It appears that you can make sections of a minimum of 3 LED's

There are several calculators on the internet for circuits of multiple LED's. They will show the power required and dropping resistors (if needed).
Here is a sample:
Current limiting Resistor calculator for leds

Page 2 of the attached will show how to use diodes to make a bridge, etc (if you can't find a way of "stealing" the appropriate VDC form the amp's circuit.

http://www1.jaycar.com.au/images_uploaded/Using%20LEDs%20-%20Its%20easy%20(JA).pdf

Personally, I would keep it simple and use a 9 volt battery and whatever resistors are required along with a small on/off toggle as your LED circuit.

I'm looking forward to reading the comments of other GC members.

Cheers

Dave


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