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I have an aluminum heat sink that threads into the end of a Mag D cell light. I have 3 Seoul Semiconductor U2SVOH stars that are artic-silver epoxy'ed onto it.
The LED stars are wired in series and so the Vf is around 10 volts. I'm also including a boost circuit that will boost a voltage up to needed output in order to hold a constant regulated current. This is my design and is based on Linear Technologies LT1619 boost controller. This circuit is 90% efficient. It employs feedback amplification to accomplish minimal IR losses in the current sense feedback resistor. Components were chosen so that it will operate on input voltage below 2 cell voltage. It also has an open circuit shutdown protection. The circuit is very heavy duty and while its size is about 1 inch square, it fits easily in the top portion of a Mag D flashlight. The best part is that the circuit is repairable because you'd have the schematic………..however, I have never blown one of these circuits.
I've had this configuration with a 3 D-cell light, a 4 D-cell light, a 6AA to 2D converter, and a 4AA to 1D converter. A 2-cell light will work if the output current is toned down a bit.
Remember power in = power out and since the output is around 10v multiplied by whatever you set the current to, 2 cells struggle to provide much over a 1 amp discharge rate.
Output current is set by R5. Schematic is shown below.
I have an aluminum heat sink that threads into the end of a Mag D cell light. I have 3 Seoul Semiconductor U2SVOH stars that are artic-silver epoxy'ed onto it.
The LED stars are wired in series and so the Vf is around 10 volts. I'm also including a boost circuit that will boost a voltage up to needed output in order to hold a constant regulated current. This is my design and is based on Linear Technologies LT1619 boost controller. This circuit is 90% efficient. It employs feedback amplification to accomplish minimal IR losses in the current sense feedback resistor. Components were chosen so that it will operate on input voltage below 2 cell voltage. It also has an open circuit shutdown protection. The circuit is very heavy duty and while its size is about 1 inch square, it fits easily in the top portion of a Mag D flashlight. The best part is that the circuit is repairable because you'd have the schematic………..however, I have never blown one of these circuits.
I've had this configuration with a 3 D-cell light, a 4 D-cell light, a 6AA to 2D converter, and a 4AA to 1D converter. A 2-cell light will work if the output current is toned down a bit.
Remember power in = power out and since the output is around 10v multiplied by whatever you set the current to, 2 cells struggle to provide much over a 1 amp discharge rate.
Output current is set by R5. Schematic is shown below.
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