MMP Problem

[Pdelcast]

Originally Posted by What's_nitro?

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

[What's_nitro?]

Originally Posted by Pdelcast

200-300 ohms might be a bit much -- ... I'd try 100 ohms in series with the LEDs to see if that fixes the problem.

Thanx!

Patrick

I was thinking of general 6v operation- 20-30 mA is fine those small LEDs. If less resistance is needed to fix it then you'll have some brighter LEDs is all. Probably shorter lifespan, but oh well...

[Pdelcast]

Originally Posted by What's_nitro?

I was thinking of general 6v operation- 20-30 mA is fine those small LEDs. If less resistance is needed to fix it then you'll have some brighter LEDs is all. Probably shorter lifespan, but oh well...

But don't forget about 5V will be dropped by the LEDs, leaving about 1.1V to drop across the resistor. 100 ohms would limit current to about 11ma.

[What's_nitro?]

Originally Posted by Pdelcast

But don't forget about 5V will be dropped by the LEDs, leaving about 1.1V to drop across the resistor. 100 ohms would limit current to about 11ma.

Oops, I forgot.