A L1 body and tailcap have been modified to host 2x123 cells and the switches resistor was
changed from a 10 ohm 1/8 watt to 33 ohm 1/4 watt resistor. The KL4 head was modified with a
Luxeon III LED emitter and the circuit and circuit housing were replaced with a DownBoy 917
converter in a custom housing.
In the photo above, clockwise from LH top corner, are:
Anode contact board (back side), DownBoy converter seated in front end of housing, tail switch PCB
showing the new resistor, old tail switch resistor, stock heat sink with Lux III LED and the lead
wires for LED to converter connections.
The brass housing for the converter and anode contact board drops down into the back side of the
LED heat sink. The heat sink mounting holes were counter sunk for flat head screws allowing for
the brass housing to drop all the way down. In order to have this light host 2x123 cells, the axial
stack of components need to utilize all available space. The brass housing has an inner lip which
both the converter board and anode contact board seat against. The boards are held apart by .045".
Between the two boards, the soldered ground lead from the brass housing has room to lead in and
pass into the ground via on the converter where it is soldered, completing the connection. The +
anode lead is a tinned post soldered first to the converter board and it lines up with a mating hole in
the anode board. As brass housing and converter assembly is dropped down into the heat sink, the
LED leads come up through their associated vias in the converter board. A thermal epoxy was used
for potting and bedding the housing and heat sink on assembly. Once in place, the LED leads were
soldered and trimmed. The anode contact board was then dropped down into the housing as it
allowed the anode lead wire to pass through. It was also bedded with thermal epoxy. Once in place,
the anode lead wire was bent over the anode contact pad and soldered with a dome build of solder.
The KL4 could have remained with the stock 5W LED and a BadBoy boost driver could have been
used for a driver. In either case, the result is a flashlight slightly shorter than the L4 but with the
advantage of having a two step switch providing typically 70 to 80 mA of current to the LED in the
Low mode and somewhere around 700 to 1000 mA to the LED in High, depending on the choice of
driver. In this case, High is about 917 mA.
Below, this light is shown below a stock L4:
