Spent last night around the table with my brother, the high school physics teacher, trying to figure out how one might calculate the resistors and type of battery that would be needed in a circuit powering 200 LEDs.
I know there are some calculators online, as Mike had suggested earlier, but because I really don’t know the first thing about electricity, I think I was probably confusing the problem… as well, our Internet connection was down, so we were googless. However, as you can see above, we eventually came out with the right number.
Then I found this formula earlier tonight…
(SupplyVoltage – LEDForwardVoltage)/ NominalLEDCurrent = ResitorValueThen I ordered a whole bunch of 270 ohm resistors and a 9v wallwart from Jameco to hopefully get these LED projects moving forward.
Related Posts: We Learned Electricity! New LCDs and Serial Ports and some Max/MSP for good measure Quick Update: LEDs Survived, Postcards are Being Distributed!
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LED circuits are fun to learn on. Once you play with stuff a bit make yourself do the math on doing say 50 LEDs in series, then in parallel and then 5 strings in parallel with 10 LEDs in series each.
From there you can make strings into 7 seg displays, learn about decade counters a bit and make a clock with a 555 timer. Takes time to learn but each step adds to your knowledge. It can make you mad, but it’s a fun thing to do when it’s crappy outside.
Good luck!
Hi Barry,
completely agree… looking forward to spending some cold days playing with these. I want to make something like the LED Fan Sign, maybe with less flashing.
Can’t wait to find out what you ACTUALLY HAVE PLANNED for these LEDs.
I mean, what can’t you do with them to get attention?
Also, I need to ask you some deets about seed-bombs.
Can’t wait to see some BCLers tomorrow afternoon (Thursday at 1pm).
Here are some details on our recipe for seed bombs, but we can get you more specifics anytime.
see you tomorrow!!