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How can I add LEDs safely to an existing power source?? Answered

I'm working on designing a way to light the interior of a NES (the original Nintendo Entertainment System.)  What I would like to do is remove portions of the case and replace them with plexiglass... then wire some LEDs together to light the interior of the unit.  I have a couple of questions. 

1.  Can I wire the LEDs and resistors into another piece of plexiglass that I've drilled holes into to accommodate them or simply affix them with hot-glue?  Do I need to wrap bared bits of wire with electrical tape or should I spray them down with more hot glue?  I've seen both in DIY projects...

2. How can I safely find a place on the system board to tap off of (power source and ground) or multiple sources if need be?  How much power can I tap without causing problems with the system's primary functions themselves?  Would I need to add any other setup to do this or is it possible to simply solder wires onto the source(s) and then "tap" the power from them to the LEDs/resistors?

Thank you in advance for your answers and please bare with me if I seem totally ignorant to the world of electronics as I am just starting off!

3 Replies

lemonie (author)2010-02-10

If you tap the main power supply, around the smoothing capacitors / voltage-regulator(s) you should be OK for power.
Hot glue is messy, you'd be best using insulated wire and mounting them neatly.


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frollard (author)2010-02-10

As rick says, use that wizard to calculate proper resistor values.

2 options:  Google 'nes mod' and see if anyone points out where on the motherboard to find power...or Poke around there with your multimeter. 
Start right next to the power barrel connector - and see if you can find ground (should be a huge solder plane that surrounds the board), and power.  Should be easy to find and solder to with those ancient huge solder pads.

How much power you can draw:  A hundred mA shouldn't kill the system, but theres no guarantees.  I think I recall the nes runs on 12 volts, which means you can run a string of 4 leds on 20mA so you could have 20 leds to your 100mA @ 12 volts (double check the voltage because I'm making that up). 

Do as the wizard says!  Run series led strings with resistors on each - in parallel.  Do not run parallel leds on single resistors.

"How to insulate the wires" - Heat shrink always looks professional and then you don't need to worry about gobs and gobs of glue mucking up the look.  Why bother to mod it with a window if you're just gonna glob the crap out of it? :D

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rickharris (author)2010-02-10

led.linear1.org/1led.wiz this will give you all the LED information you need also calculate various values for you.

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