array of LEDs

Forum 2005-2010 (read only) General Bar Sport
1

So I am building my FTIR touch screen and I need to solve a few issues:

The best and easiest way to wire up all the LEDs (they are in 2 x 25 and 2 x 14 arrays - not yet wired up so could be parallel or series) - they are held in 15mm aluminium channel with 5mm holes. I don't really want to be messing with loads of resistors on every LED.

The best and easiest way to power them - I don't really want to mess around with this so something built for purpose is preferable (you know what I mean! :slight_smile: )

Each LED is 100mA and 1.5 volts - so almost 8 amps of power to cover all 78 LEDs

James

2

Wire them up in strings of 7 LEDs each, with a 15 Ohm, 1/2W resistor.

For the 2 strings of 4 LEDs, use a 62 Ohm, 1 or 2W resistor.

Then you can power them all with a 12V, 2A or more, regulated power supply.

It's true that you'll only be drawing abouyt 1.2A, but running the power supply at 60% or less of its capacity will make it run cooler and last longer. Oversizing the resistors also makes them run cooler. They won't last noticeably longer, but your fingers might if you accidentally touch them ;D

Ran