chimo
Flashlight Enthusiast
I finally got around to making something with the LTC3490 chips I picked up. These are minimal component 350mA constant current ICs that make it easy to power a LuxI. I had originally planned on creating a Solitaire Pill, but I got a couple of empty ArcAAA heads from cy and decided to change hosts.
I started by a quick etch of a test board to check the inductors I had on hand.
Since that worked OK, next I planned on a dead bug style pill. After working out the layout, I found out that pbarrette had done a very nice one. I used a modified version of his (Thanks pb). I had to choose between emitters - I had one hand a R3K (LuxI) and a TW0H (LuxIII). I tried them both on the test board, asked the wife and we both preferred the TW0H.
I polished the reflector and bored out the ArcAAA head a bit to make it a little "roomier" and assembled the pill (sorry, no photos ). I potted the pill in Arctic Silver to help conduct heat away from the components.
Here is a photo of the finished head.
A beamshot against the back of the sofa.
Beamshot compared to an ArcAAA with the LED replaced with a great performing CS LED. The mod had a hotspot about twice the intensity of the ArcAAA but the flood portion blows the Arc away. The colour is also much nicer. This beamshot does not do the output justice. I tried a ceiling bounce test and this is significantly brighter than three ArcAAAs (on at the same time) with the CS LEDs.
Left - ArcAAA(w/ a CS LED), Right - 3490 TW0H
What's the price for this increase in brightness? Runtime. This little baby is a real pig on batteries. It also gets pretty warm/hot. The LTC3490 chip is supposed to have a low battery cutout of 0.85V (when configured in single cell mode) so it should protect your NiMH collection. The chip is also supposed to PWM the output if battery voltage is too high and the current starts to rise above the setpoint. (good for Li-ions??).
Between 15-20 minutes runtime was typical using some oldish 750mAh Energizer NiMH AAAs.
Here's a runtime graph:
This was a fun mod but I have used up all my enjoyment making this one .
Paul
I started by a quick etch of a test board to check the inductors I had on hand.
Since that worked OK, next I planned on a dead bug style pill. After working out the layout, I found out that pbarrette had done a very nice one. I used a modified version of his (Thanks pb). I had to choose between emitters - I had one hand a R3K (LuxI) and a TW0H (LuxIII). I tried them both on the test board, asked the wife and we both preferred the TW0H.
I polished the reflector and bored out the ArcAAA head a bit to make it a little "roomier" and assembled the pill (sorry, no photos ). I potted the pill in Arctic Silver to help conduct heat away from the components.
Here is a photo of the finished head.
A beamshot against the back of the sofa.
Beamshot compared to an ArcAAA with the LED replaced with a great performing CS LED. The mod had a hotspot about twice the intensity of the ArcAAA but the flood portion blows the Arc away. The colour is also much nicer. This beamshot does not do the output justice. I tried a ceiling bounce test and this is significantly brighter than three ArcAAAs (on at the same time) with the CS LEDs.
Left - ArcAAA(w/ a CS LED), Right - 3490 TW0H
What's the price for this increase in brightness? Runtime. This little baby is a real pig on batteries. It also gets pretty warm/hot. The LTC3490 chip is supposed to have a low battery cutout of 0.85V (when configured in single cell mode) so it should protect your NiMH collection. The chip is also supposed to PWM the output if battery voltage is too high and the current starts to rise above the setpoint. (good for Li-ions??).
Between 15-20 minutes runtime was typical using some oldish 750mAh Energizer NiMH AAAs.
Here's a runtime graph:
This was a fun mod but I have used up all my enjoyment making this one .
Paul
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