Thread: MMP Problem
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Pdelcast
RC-Monster Titanium
 
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01.12.2011, 10:41 PM

Quote:
Originally Posted by What's_nitro? View Post
All LEDs need resistors, as they are basically a short circuit otherwise (Light Emitting Diode). The voltage drop of an LED is pretty large- ~2.5 volts is pretty common, so at 5v you could get away without a resistor. Each string should have a 200-300 ohm resistor in it's series to limit current to 20-30 mA. This is more to protect the LEDs from popping than it is to prevent overdrawing the BEC circuit in an ESC. Patrick would know better than anyone if the lack of a resistor could cause a problem, and why.
200-300 ohms might be a bit much -- but I'm thinking the LEDs might be somehow triggering the overcurrent sense on the BEC. Not sure what mechanism (maybe a negative resistance slope on the LEDs, as they turn on, is the cause??)

I'd try 100 ohms in series with the LEDs to see if that fixes the problem. I'd be happy to try to reproduce the issue in the lab, and see if I can find an easy fix.

Thanx!

Patrick


Patrick del Castillo
President, Principle Engineer
Castle Creations
   
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