The other day a friend of mine stopped by with a problem he thought I could help him out with. He's a servayer and his old style military type flashlight wasn't up par with the new LED flashlight. What to do? Take that new LED flashlight (freebie) and put the guts into the old flashlight.
*the only extra parts I needed was some wire, a 3AAA battery holder and some 1in. SCH40 PVC pipe.

Step 1: Take It Apart

This is the easy part. CHECK THE PHOTO

Step 2: Wire Up the Lens

1. DESOLDER SPRING off the LED PCB and save for use later.
2. Take the LED PCB and solder on some wire leads
3. Take the OLD LENS and drill a hole ( big enough for the POSITIVE WIRE LEAD ) somewhere near the metal contact ring.
4.a. Thread the NEGATIVE WIRE LEAD thru the rear of the old bulb holder.
b. Thread the POSITIVE WIRE LEAD thru the hole drilled near the contact ring.
5.a. SOLDER the NEGATIVE WIRE LEAD to the metal part of the old BULB HOLDER.

It's ok if the LED lens floats, it will self center and tighten up when reassembled.

Step 3: The Battery

The problem: The old flashlight uses 2 D cell batteries and the LEDs use 3 AAAs.

The solution: Find another battery holder like the one that came out of the freebie flashlight and run those two series battery circuits in parallel.


1. SOLDER a WIRE LEAD to the POSITIVE end of one of the battery holders
2. SOLDER a WIRE LEAD to the POSITIVE end and a WIRE LEAD to the NEGATIVE end of the other battery holder.
3. HOT GLUE the POSITIVE battery holder ends together.
4. HOT GLUE the POSITIVE WIRE LEADS down and out to the negative end with the wire lead.
5. HOT GLUE the NEGATIVE WIRE LEAD down and out to the negative end without the wire lead.
6. SOLDER the NEGATIVE WIRE LEAD to the edge of the negative end.

Step 4: The Battery Holder

1. Cut a 4.5 in. piece of 1 in. SCH40 PVC pipe.
2. DRILL a 1/16th in. hole into one end of pipe.
3. REMOVE 2 negative and 1 positive caps off of the D cell batteries.
4. SOLDER the SPRING to the outside end of one of the negative battery caps.
5. Take the positive wire leads from the battery and run thru the plastic gasket thing that came off one of the batteries.(this is an insulator, very important)
6. DRILL a 1/16th in. hole near the edge of the other negative battery cap.
7. SOLDER the POSITIVE WIRE LEAD to the inside end of negative battery cap with hole.
8. SOLDER POSITIVE BATTERY CAP and NEGATIVE BATTERY CAP with spring together, let cool and HOT GLUE to PVC pipe end without drilled hole.
9. Put battery into new battery holder NEGATIVE end first.
10. Screw the new positive cap to the PVC pipe.

Step 5: Reassemble

1. Reattach the lens assembly.
2. Slide new battery holder with batteries NEGATIVE end first.
3. Reattach the base of the old flashlight and go have some fun in the dark.CFH
nice. I wonder, what happened to my us army flashlight? I can't find it.
Great conversion! I have an old flashlight like this kicking around and I am going to give it a try... always nice to see somebody come up with a practical hack for a vintage tool.
Looks good. I might ask what a servayer is, but I think you mean surveyor? L
yep, it is surveyor. I don't know why spell check didn't fix it so I thought it was spelled right. I was an Engineer for two years before I learned how to spell engineer. Thanx for my first comment, you're awesome.
Thanks - it's a good Instructable, hope you've got some more to come. L
lemonie, you make me chuckle ; )
If you can fit them, I'd recommend AA batteries over AAA, they tend to have much higher capacity so will last longer but have the same voltage so will work fine with the LEDs. Ideally it would be cool to keep the two D batteries and use a voltage boost, because two D batteries have even more capacity than 3 AAs, but that's adding complexity.
Simplicity is cool but usefulness is coolest. How would I get this voltage boost? Please reply and send me toward the light. CFH
Actually, it wouldn't be necessary to use the second set of batteries in this light. The extra space would be good for storage or a second set of batteries. You could use Velcro or a small magnet to keep the first set of batteries in place.
My original plan was to use just the three AAAs and fill the void with a snake bite kit. I didn't have one to spare ( we're in the middle of a drought here in So. Texas and the Copperheads and Rattlesnakes have moved closer to the houses looking for water ). I thought that the battery configuration I used would extend the time between battery swaps, no? Cool name Atombomb.

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