PR Bulb to MR16 bi-pin base HOWTO

Hi all,

Well I promised a HOWTO for those wanting to convert your PR base bulbs into MR16 bi-pin bases, but I forgot all about it and ended up taking pictures only near the end. /ubbthreads/images/graemlins/banghead.gif Sorry.

I haven't perfected these, and everyone I do comes out different. They're all ugly, and I'm embarassed to let anyone see them /ubbthreads/images/graemlins/blush.gif, but here goes:

You need to acquire:

PR Bulb
(2) female Molex power pins. Jameco #224215 http://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=429703&cgrfnbr=501&ctgys=
small heat shrink tubing
high temp epoxy
masking tape
22awg wire

- First put the bulb into a plastic bag and crush the glass with a pair of pliers or a hammer.

- Remove the glass and use a small standard screwdriver to scrape out the remaining glass and potting material. This will take a while, but you can get it all.

- I use a dremel with a small round grinding bit to grind out the last bits of potting material. When you're done you should have bare metal on the inside.

- Break out the black insulating bottom and center nub.

- strip about 4" of 22awg wire

- cut the Molex pins just behind the cylinder. You only need the part that's shaped like a tube

- solder one wire to each tube

- bend the barbs of the Molex pins flush with the body of the tube

- cut heatshrink and use to cover the tubes.

- once cooled, trim top flush, bottom just longer than the Molex tube

- mix up a small bit of epoxy and glue one heatshrink covered tube to the body of the PR base and let dry making sure the wires exit near the center of the bulb base and do not touch the base

- repeat for the other tube

- now you have the recepticles for a MR16 bulb and wires attached

- cut a slit in a short piece of masking tape, and pass the wires through. Use the tape to seal the bottom of the PR base.

- mix up some more epoxy and fill the bulb base. I like to stick toothpicks in the Molex pins to keep the epoxy out.

- after the epoxy dries, remove the tape and trim up any rampant epoxy



- bend one wire over the rim of the PR base and solder. Trim off the tail. Negative connection is now made





- position the other wire so that it sticks straight up from the center of the base.

- mix up more epoxy and let a couple large drops fall onto the base on either side of the wire. Rotate the bulb base by spinning the wire slowly horizontally to keep the epoxy from running. When it sets up, you'll have a nice bulbous base with a wire sticking up.



- you can either clip it off and tin it, or coil it up and make a nice solder blob.



- VERY IMPORTANT. You need to make sure you haven't shorted the pins, so test with a multimeter. One pin should be connected to the metal PR base, and the other should be connected to your solder blob and NOT THE BULB BASE.

- All done!

Wow, very nice, very nice indeed! Perhaps you should make me one /ubbthreads/images/graemlins/smile.gif And while you are at it, you can make me one with pins for a tigerlight lamp assembly, and another for pins to a newbeam module /ubbthreads/images/graemlins/wink.gif Instead of breaking the glass, you can hold the glass in a pair of pliers, hold the metal over a flame for a short while, then pull the metal off (with gloves or a cloth) and the bulb is intact. No broken glass to mess with, and very little potting material.

Spud

That's some nice work! (in my best Chief Wiggum voice)

If you used the MR16 lamp itself to hold the Molex pins in place during the potting, could you eliminate the step of gluing the heat shrink tubing to the PR body? Or is it too unwieldy to maintain alignment that way?

John

Yeah I tried without the heatshrink and it's just too hard to hold the pins in alignment without shorting them. Plus you have to figure out how to keep the epoxy out of the Molex pins but fill the PR base while holding the base and bulb. A big PITA.

Thanks a bunch for inspiring me to finally do something I've been meaning to do. When I get a 4D mag I'll get around to doing the mr16 base, but I just now made a tigerlight base. Except mine doesn't come out. I soldered wires to the pins on a tigerlight LA from flashlight lens. It has a D cell mag retainer between the LA and the bulb base so I can even screw in the LA if I add a bit more epoxy to the LA and retaining ring. Now I'll be able to take that 2D mag with 6AA's and use a 14 watt light instead of that weak 5 cell bulb that is in it.

Spud (I'll post some pics here shortly)

Excellent. This is the tutorial that I've been anxiously awaiting. /ubbthreads/images/graemlins/smile.gif I had previously theorized a slightly different approach, but I have to say that I like the way that your final adapter turned out. I had considered using heat shrink tubing previously, but I figured that in such a small space and with such small tubing that it would be a real pain in the butt to work with, but if it works well for you, I think I might just give it a shot to. /ubbthreads/images/graemlins/smile.gif

Here is the route that I was considering trying. I thought that I would just take the negative connection and simply solder it to the spot on the base that the original bulb's negative contact was made at. Then, for the positive contact, I would drill a small diameter hole (just large enough for the wire to pass through) down the center of the bulb and then solder it in place. Now I may just try a blending of the 2 ideas and see what I can come up with.

I only wish I had a digital camera so that I could take pictures just in case I do come up with a really neat design. Those are some great close up pictures that you posted. It just amazes me how you guys can get such great and clear looking close-up pictures like that. /ubbthreads/images/graemlins/smile.gif

With any approach a person may take on building one of these, I pity the person that is trying to do one of these without a Dremel tool or some near equivalent. Of course I figure that most flashlight modders here have already "seen the light" and have one of these handy modder tools on hand anyway. If not, you are missing out on one of the most handy tools that you will ever buy. Mine has already saved me much more money than it originally cost.

You know, I just was thinking and I bet a drill press might also be quite effective on drilling out the insides of one of these bulbs, assuming that you could position and hold the base just perfectly. It would probably go a lot quicker than using a Dremel tool if just the right technique could be perfected. Just think, with one flick of the wrist, you could have a base cleaned out in a matter of seconds.

Hmm... I bet you could use a pair of Lock-Jaw pliers to hold the bulb in place and then use a drill press to hollow out the inside of the bulb base. I think it would be important to get an efficient technique such as this going if a person was going to do a lot of these. Every little optimization to the process would help.

Too bad that Carley still refuses to make up some of these adapters for us. It would be a piece of cake for them to do a run of them because they are already set up to do this sort of thing. It would be almost pure profit for them. Oh well, their loss...