Hello everyone. I don't post very often but have a couple of questions and maybe something to offer the board.
A year or so back I built three 3D Mag lights with the PTS-2D heatsink and three P4 LED stars in series. I designed my own boost circuit utilizing Linear Technologies LT1619 IC. (I'm an electrical engineer that has a bunch of experience with dc-dc converters, so why not).
It turned out to be 90% efficient and held regulation down to 2.50 volts. After that the efficiency started dropping off. I was only pumping out about 0.400 amps through the LEDs as I wanted to get a number of hours out of the batteries. However it's adjustable up to near 2 amps through a resistor value change associated with the gain of an op-amp feedback network. The reason for the added circuitry was that I didn't want to waist power through a current sense resistor but rather use a small value and then amplify this up to the desired feedback (ie: current set point). Also the circuit has built in over voltage shutdown in the event that one of the wires to the LEDs goes open circuit.
This last weekend I chaperoned a youth group in a campout and boy was that light fun. So I want to do another one. My question to the board is:
Is it worth doing another one with all the cost of custom stuff or is there something on the market now that is already designed like this? I think I was into it around $90.00
I happened to use three 2500 NiMh cells in those micky mouse plastic adapters just because I didn't want to run my D-cells down for a one night trip. When the light was on they were pulling a little over an amp out of them. As it was the batteries held up as I didn't keep it on all the time…..so now I'm thinking of doing a one D-cell size with the AA to D cell adapter.
So this is my next question. If I do another mod, I'd like to find or make a one cell D mag host where I put in at least three AA cells that are configured in series. Does anyone know of anyone offering this service? And also the 3AA cell or 4AA cell to D-adaptor?
[FONT="]Thanks in advance[/FONT]
A year or so back I built three 3D Mag lights with the PTS-2D heatsink and three P4 LED stars in series. I designed my own boost circuit utilizing Linear Technologies LT1619 IC. (I'm an electrical engineer that has a bunch of experience with dc-dc converters, so why not).
It turned out to be 90% efficient and held regulation down to 2.50 volts. After that the efficiency started dropping off. I was only pumping out about 0.400 amps through the LEDs as I wanted to get a number of hours out of the batteries. However it's adjustable up to near 2 amps through a resistor value change associated with the gain of an op-amp feedback network. The reason for the added circuitry was that I didn't want to waist power through a current sense resistor but rather use a small value and then amplify this up to the desired feedback (ie: current set point). Also the circuit has built in over voltage shutdown in the event that one of the wires to the LEDs goes open circuit.
This last weekend I chaperoned a youth group in a campout and boy was that light fun. So I want to do another one. My question to the board is:
Is it worth doing another one with all the cost of custom stuff or is there something on the market now that is already designed like this? I think I was into it around $90.00
I happened to use three 2500 NiMh cells in those micky mouse plastic adapters just because I didn't want to run my D-cells down for a one night trip. When the light was on they were pulling a little over an amp out of them. As it was the batteries held up as I didn't keep it on all the time…..so now I'm thinking of doing a one D-cell size with the AA to D cell adapter.
So this is my next question. If I do another mod, I'd like to find or make a one cell D mag host where I put in at least three AA cells that are configured in series. Does anyone know of anyone offering this service? And also the 3AA cell or 4AA cell to D-adaptor?
[FONT="]Thanks in advance[/FONT]
