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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!


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.


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