Customized Surefire MN03 Bulb Burns Out from Surges

[DR_MARK]

Probem: Customized Surefire application using MN03 bulb powered by 6VDC 1400mA power supply burns out from power surge.

Anyone have any ideas for a protection circuit that could be used to prevent surges from causing the bulb to burn out?

e.g.: a resistor in the circuit to DIM the light or a fast-burning fuse?

I tried a rheostat in parallel with the bulb. Rotating the rheostat caused the metered output voltage to drop, but the bulb would not even illuminate when the rheostat was at maximum "open-least resistance".

 

[kosPap]

not up to mu league, but I believe that someone suggest a pack of NTC resistors of very low value...it is a resistor that allows current to flow only once it gets warm...

 

[Bullzeyebill]

If we could talk AW into producing a SF E series soft start switch like his C series model, that would do the trick. I think that your fix, for now, is to use the LumensFactory lamps for your E2. They are very hardy, and should not instaflash due to turn on inrush current.

Bill

 

[Jumi]

You are overdriving the bulb.
Bulb is meant to be used with 2 Primary CR123 which nominal voltage is 3V but voltage sags due to battery internal resistance at MN03 1.1A current.
If you are driving MN03 bulb from powersupply I would start at around 5V, not 6V.

Juha

 

[Bullzeyebill]

Whoops, I missed that it was being driven off of a power supply. Yes, the MN03 would be, at the most, a 5 volt lamp. Can not overdrive it, as it is on the edge already, probably a 20 hour bulb. Look at common mag bulbs and the voltage rating for them is always lower than the cell requirement to run them at spec.

Bill