burger2227 wrote:Converting a D cell flashlight to LED involves soldering a 10 mm LED into an old flashlight bulb base:
Carefully break the old bulb and dig out the socket insulation enough to get to the bottom of it. Unsolder the
existing wire so that a small hole can be seen through the bottom. Insert the long LED leg through the hole
while bending the cathode leg toward the notch in the side. Some larger LED leads may not bend, but the
cathode leg may be wide enough to slip into the side slot. I had to cut the notch out a bit for some leads.
I used a 2 AA battery holder to keep the circuit protected and soldered the coil center tap to the spring of the leading battery.
This will give the positive 1.5 volts from the second battery in the holder as the circuit is in the first battery's holding place.
The battery minus wire goes to the bottom spring. Use extra wire to allow the wire to be twisted when the end is screwed back on.
The black circuit ground wire goes to the LED side of the grounding switch. In this case it was the long bus
coming from the switch to the reflector. The reflector back may be used as common too, but is hard to solder.
In this case I just wrapped the solid black wire around the bus and slid it down until it was spring held to the
side of the flashlight switch. The bus does not move with the switch. If it did, I would have had to solder it.
Instead of using the red wire from the holder (I cut it short) , I ran a red wire from the circuit to
the LED bulb base tab directly as shown at the bottom of the picture above.
My next project will make a rechargeable flashlight that comes on when the electric power goes off.
It will incorporate the trickle charging AC circuit I used with the power failure outlet boxes.
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