Difference between revisions of "DIY P60"

[[File:P60-parts.jpg|thumb|400px|P60 parts: Reflector, big spring, LED, driver, and little spring]]'''The drop-in''' There are a lot of drop-ins available. Most have an 18mm diameter brass pill (some are aluminum) and come with a big spring that bears against the head of the flashlight and presses the reflector against the glass. With some hosts, you don't need this spring. The drop-in also has a small spring that will be soldered to the bottom of the driver board to make contact with the positive end of the battery. Some driver boards already have a spring there. The biggest difference between drop-ins is the reflector. You can choose smooth (SMO) or orange peel (OP). Smooth usually has a little better throw but may show artifacts or rings in the beam. OP will tend to reduce throw, have a little more spill, and smooth out any beam artifacts. OP is more common, but SMO works fine with XP-G and XM-L LED's. The other variable in reflectors is the hole at the bottom for the LED. Many times the hole is 7mm which is big enough for the metal ring around XR-E LED's, but is also ample for larger die LED's like MC-E and XM-L (a P7 or SST LED requires an even larger hole). Some reflectors have a smaller hole for XP-E and XP-G LED's. The shape of the bottom of the LED can be important as well since it will fit over the LED board and connections.

[[File:P60-ledmounted.jpg|thumb|400px|Mount the LED on the pill so that the LED is right in the center and the holes for the leads are not coverd.]]The LED needs to be mounted to the brass pill so that the pill can soak up heat produced by the LED. Use a very small amount of thermal adhesive or thermal epoxy to get good contact between the LED board and the brass without any air gaps. But even the best thermal epoxy will get in the way of the heat transfer so use as little as possible. More is not better. An epoxy like Arctic Alumina or Arctic Silver works great, but once it sets it will be impossible to remove the LED without damaging it. A silicone thermal adhesive like Fujik from DealExtreme seems to work fine and can be removed. Some people might choose to use non-adhesive thermal compound instead of adhesive, but then the only thing holding the LED in place is the soldered lead wires and pressure from the reflector.

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). 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.

[[File:P60-driverdry.jpg|thumb|400px|File the driver down until it fits snugly in the bottom of the pill and file one side flat for easier removal.]]In the picture above you can see the driver still has nubs left over from the production of the circuit board. These need to be filed down so that the driver will fit snugly in the bottom of the pill. It is helpful to file one side of the driver flat so that you can pry the driver out of the pill with a small flat head screwdriver. Test the fit as you file down the nubs. Sometimes drivers run a little large or small.

[[File:P60-leads.jpg|thumb|400px|The driver board with the lead wires soldered in place.]]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.

If the LED is working, you can go ahead and solder the driver board to the pill. This isn't easy to do because the pill will soak up the heat from the soldering iron. It is easy to get a blob of solder on the outer ring of the driver, but harder to bridge over to the pill. However this is essential, not just to hold the driver in place but to complete the path from the negative end of the battery, through the switch, up the metal body tube of the flashlight, to the pill, and to the driver via the solder bridge. Try to get two good solder bridges in place. Use your DMM to make sure there is continuity between the pill and the outer ring of the driver.

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. Now you can put the drop-in in a light and see if it works!