MicroSquirt.com read only forum (Jan.15,2018)

I did a search and came up blank so if any one can give me a maybe well explained answer I'd be happy. I am planning my wiring for a MicroSquirt V3 install and want to add these lights into an instrument cluster I'm building. In the wiring instructions for the MicroSquirt is states that if using a 12v power source then a 1K ohm resistor needs to be used. To be safe I checked some on-line calculators and no matter how far, within reason, I pushed the inputs the resistor value suggested was never more than about 600 ohms, I believe 510 ohms was correct for true inputs. I don't want to break anything before I get to at least play with it for a little while, bad memories from my childhood, so if someone can explain that would be great. It's not a cost thing as resistors are dirt cheap, but I want the lights to shine bright enough to see in daylight without causing any damage to the unit.

Thanks and Merry Christmas to all

dd,

Sure, you can use 510 Ohms (as long as the LED you choose can handle 30 mA - most can). The output on MicroSquirt itself can handle much, much more.

The resistor is there to limit current, not necessarily to control brightness (PWM is a much better way to do that). To my eyes, the resistance value doesn't make a lot of difference unless it is on the extremes of the permissible range, but you may see it differently. And if you want every last percentage of brightness, then run as much current as the LED can handle. The only drawbacks are that the LED will get hotter, so it may not last as long (but this shouldn't be a huge issue), and it may make for a LED that's too bright at night when driving (if you do any night driving).

Lance.