04-10-2010, 09:18 AM
torikoos Wrote:that's somewhat right indeed. They do have a load, be it a very small one, up to 1.5V for a standard led, no resistor is required, but in our situation, with higher voltages on tracks and leds build in as headlights etc, we do need one. The site has resistor info too.
it has to be said- you should be very careful about using LEDS without a series resistor
I am experimenting ATM with building my own streetlights/trafficlights etc using SMD led's of various types
I have a rather nice dual output variable voltage powersupply with current limiting at my disposal (about 200 bucks worth)
while testing out the various leds I was looking at for traffic lights, I managed to burn out an amber led within about 3 minutes, although the voltage was only 3.6v instead of 3.5v, the current rose from 10ma to 60ma in that .1 of a volt
with even a low value resister it wouldnt have happened (or if i had turned on the current limiting on my power supply)
but having a power source without a series resister that isnt a `current limited' type will damage the leds longterm if its voltage isnt extremely tightly regulated
JFYI
poopsie chicken tush