Here I have built the LM2621 into a dummy D-cell battery.
It is designed to be placed in a 2 or 3 cell light, replacing
one of the batteries while allowing regulated voltage output
from the remaining cell(s). The case is a Fuji 35mm film case.
A small bolt serves as the positive contact for the Voltage
out. The head of the bolt is seen resting on a stand off washer
to give it the appropriate height. Inside the case is a lockwasher
and a nut with the Vout wire from the LM in between the two
for contact. The negative lead for the board is protruding through
a hole drilled in the top of the case for attachment to the
switched negative side of the flashlight circuit. Turning on
the light turns on the board as well. I had to drill 3 holes
in the top of the device to avoid overheating the board while
attached to a Luxeon Star.
Inside the case from the bottom looking through to the top.
The nut inside is covered with electrical tape.
The bottom contact of the unit is a brass finger pull found
on older sliding closet doors. I just happened to have one lying
around and it fits exactly in the recess of the Fuji film case.
The top of the unit showing the bolt head and stand-off washer.
The negative lead of the board protrudes through a hole in the
top. That lead is passed through the head of the light and wedged
under/attached to the switched negative side of the flashlight
circuit. The bottom of the case is to the right.
Here you can see the shape of the brass fingerpull and the
lid of the film case and how they match up. I soldered the positive
wire to the fingerpull using a modified spade connector. With
this device in the circuit I can supply a regulated constant
current to an array of LEDs or an LS module with the advantage
that the LEDs will not dim as battery life diminishes.
