Current Draw for 178 RED LED's @ 20ma each. Is this really going to require 12vdc 3560ma power supply?

Want to be sure before I purchase AC/DC Wall Wart. I was thinking a 1000ma supply would be ok. I'm I wrong on that or I'm I missing something.

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keydogstony (author) 8 years ago
I guess we were all wrong. I completed the project with 177 LED's and it actually works with a 9 v battery. Not sure how long but it work for the few minutes I hooked it up. Wire 5 LED's in series with 68 ohm resister for each segment and then wired them all in parallel. I hooked up the 9v battery just to see what would happen. They all lit up bright. I may add more about this later.
AndyGadget8 years ago
You're right with your calculation - 3.56 Amps. If you haven't already bought then, consider low current (2mA) LEDs (but don't get them from Maplin - Pricy!)

What are you making?
keydogstony (author)  AndyGadget8 years ago
Making a sign. The real intention was to put into my Truck and run off battery. A 4 amp 12vdc supply would be pricy as well. It needs to be bright. :) But would also like to use with a Wall Wart for inside use as well. I don't guess a LED Driver would help? Any idea?
If you're running off your truck battery, you've got 12VDC at "infinite" amps already :-) Make sure you put a 4A fuse inline with the sign, just in case.
If you're looking at having all LEDs on at once rather than individually controllable (which would be a wiring nightmare), you might be able to do something with these flexible LED strips. The ones I looked at draw 100mA for a 15 strip, so total would be a bit over an amp. They're meant for auto use so should be bright enough.
keydogstony (author)  AndyGadget8 years ago
Well, I did find on eBay some 4amp 12vdc supplies for around $12.50. Not too bad. LapTop Supplies. But something less expensive would be better.
kelseymh8 years ago
Yes. Current adds linearly, and your calculator has told the truth: 178×20 = 3560 = 3.56 amps. You will need a 4A rated power supply. Or, as AndyGadget suggested, get yourself low-current LEDs instead.