Building your own custom P60 allows you to pick out whatever LED and driver you want to make a P60 drop-in perfect for you.
Things you will need
- Empty drop-in. This includes brass pill, reflector, big spring, and little battery spring.
- Driver. The circuit board. See Popular drivers for some examples. Usually includes leads to the LED.
- LED. Make sure you get one already mounted to an aluminum board, no bigger than 16mm diameter.
- Isolation disk. Or you can make your own. Keeps the aluminum reflector from making electrical contact with the LED board.
- Soldering iron
- File to smooth edges and shape the circuit board
- A vise to hold the work
- Magnifying lens or jeweler's loupe to check your solder joints
- Digital multimeter (DMM) to check continuity
- Thermal adhesive or epoxy
LED The LED should already be mounted to an aluminum board which will have solder pads for connections to the negative and positive leads from the driver. Unmounted LEDs can be mounted to a board using reflow soldering, which is more than most people want to deal with. 18mm boards or larger simply won't fit. A 16mm board is a tighter fit and 14mm is about perfect. Smaller boards and square boards are sometimes used as well. The boards usually have indentations in the edge so the board doesn't block the holes where the leads will come up out of the pill.
Driver The driver should be 17mm in diameter. This is the most common size anyway, but still requires some very tiny soldering joints. The key thing with the driver is that you pick one that will work with the battery voltage you are supplying and with the LED you want to use. Sometimes the leads are already soldered to the driver, which is helpful. There is usually a solder pad marked with a + for the positive lead to the LED. Sometimes the negative to the LED is marked by a -, but not always. Look on discussion boards if you aren't sure. The drivers themselves usually don't have instructions.
Mount the LED
You want the LED centered on the pill for the best beam quality. You can get it close by eye and then screw a reflector over the LED (don't tighten it all the way down or it could move the LED) to make sure the LED is in the middle of the opening. If the reflector has a big enough hole you may be able to make adjustments with the reflector in place. Once the LED is centered, you can clamp LED down until the adhesive sets. Use something hollow like a pen cap over the LED so you don't damage the dome. Once the adhesive sets up, check the centering again to make sure it didn't shift.
Get the driver ready
Next you will need to solder the leads to the driver board. The black wire connects to the negative pad and the red one to the positive. This can be challenging because the board is small and the wires are surface mounted to small pads. It helps to silver the ends of the leads with solder so they will stick better. It may also help to bend the exposed wire ends. It is nice to have some kind of vise to hold the driver and a magnifying lens doesn't hurt either. Once the leads are in place, give them a tug to make sure they are on there good and use your DMM to test that there is not a short between the positive and negative pads due to oversoldering.
Wire the LED
Once this is done, you can test the drop-in by holding the positive end of the battery up to the middle of the driver board and then use a piece of wire to connect the negative end of the battery to the brass pill. The LED should light up. If the driver has modes, you can test whether they are working by breaking contact and then touching the pill again with the wire. If it doesn't work, then check your soldering.
Usually you also need to attach the small spring to the bottom of the driver board. Put two blobs of solder on the outer parts of the center of the driver. Then put the spring in place and re-melt the solder. It is essential for the spring to be very secure. If it comes loose, it could cause a short between the negative and positive parts of the driver board. This would produce a dead short for the battery when the light is switched on, possibly causing a fire or explosion. Give the spring a good tug and check it from time to time as you use the light to make sure it is not coming loose. If you turn the light on and it does not light up, turn the light off immediately and make sure there is not a dead short.
With the spring in place, you can put an isolation disk over the LED and screw down the reflector. Since the reflector is made of conductive aluminum and would otherwise touch the two solder points on the LED board, the isolation disk is essential to avoid a short. Attach the big spring to the pill and screw the reflector down (sometimes the big spring isn't needed). Now you can put the drop-in in a light and see if it works!