Warm-up and Accel LED wiring

Forum for discussing how to install MicroSquirt(TM), choose and troubleshoot sensors, wiring, and communications for MicroSquirt (TM) and MicroSquirt Module(TM).
Forum rules
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Post Reply
dumbdumb
MegaSquirt Newbie
Posts: 1
Joined: Fri Dec 23, 2011 12:58 am

Warm-up and Accel LED wiring

Post by dumbdumb »

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 :yeah!:
Bernard Fife
Super Squirter
Posts: 1009
Joined: Mon Feb 16, 2004 3:15 pm

Re: Warm-up and Accel LED wiring

Post by Bernard Fife »

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.
Post Reply