I did not think this would work...

I decided to try out my luck with modding an old 3D MugLight. I bought a 1 watt LS, heatsink, Fraen optic w/ holder and a 1ohm, 1watt resistor from Elektrolumens. I sat down to start the mod and I realized that I had an older MugLight that had a larger ID than the OD of the heat sink.

After a few calls, I convinced my brother to trade MugLights. I did not realize that he gave me a 4D Muglight until I got home. Being an impatient person, I decided to try it anyway.

After making the connections to a broken and cleaned out bulb base, attaching the resistor in series, putting the wires though the heat sink, attaching the leads to the star, desoldering and resoldering the leads because I forgot to place the bulb retaining cap on, I tucked the wires in and pressed on the heat sink. I hit the switch and got lots of bright light!

I placed the centered optic holder on the heatsink, took the lens out of the head and carefully screwed the head until the lens touched the optic holder.

At this point, I was quite impressed that the light worked. I wanted to measure the current, because I did not think this light could work with 6 volts. I unscrewed the tailcap, attached a lead of my DMM to the barrel, and the other lead to the bottom of the battery stack. With the scale on the DMM set to 10 amps, I was getting 2.0 amps running through the circuit.

I was honestly expecting to release the magic smoke, but the light still works after a week of playing. The barrel gets warm, but not uncomfortably warm, so I guess the heat sink is working.

My questions are: Did I measure the current correctly?
Given that there are 4D cells and a 1 ohm resistor, I did not think that this light would last too long. I did not take note of the Vf of the LS Star, but I do remember is was a Q3. I am not sure how to measure the Vf either. I would appreciate your thoughts or comments on this mod.

Thanks!

Myron

put a dummy D-Cell in there. You get minimal gain in light past about 800mA. You can make a dummy cell with a piece of wood dowel, and a bolt/nail/wire/something as a center conductor.

No big rush to measure Vf, but if you want to know how, just unscrew the lens and measure the voltage directly across the LED.

No real need to, though. If you really have six volts and two amps then there's two volts across the one ohm resistor leaving four for Vf at this extreme current. All quite realistic.

Now there's 8 Watts (two amps times four volts) developed in the LED, a considerable over drive. Now at 17 degrees C per watt die to slug, that's 138 degrees C rise. Given the Tj max of what C unless that slug is what 18 degrees below zero (meaning the case is liquid nitrogen temperatures) the die is being abused..

IMO you've every right to be surprised, I am........

Doug Owen