Maglite mod

Here's a 2D Maglite mod. The idea is not so much the LED but the use of the full torch (no cables).



It's a 2D Maglite with a Terralux drop-in LED upgrade (3*Cree XR-E run at 12watts, manufacturer claim 700 lumens). Batteries are 2* D Cell Li-ion (7.2V 5Ah gives 2.5hrs run time). Switch is a piezo and toggle circuit.

This guy has been to 45metres on a few occassions now and compared to other PVC torches I've made is compact and 'bomb proof'. Great day torch, or back-up night torch. Feel free to use and abuse the idea.

Instructions
Take a 2D Maglite and remove the switch barrel. Remove the rubber switch cover and use a 2mm Allen key to release the barrel. This is the only way so don't try coming in from the front on that circlip, you'll never get it out. Slide the barrel out the back. Cut off the narrow front section of the barrel and discard. Push out the blue plastic insert and discard the switch mechanism. Hacksaw the blue insert in half, to free up space for the piezo. Cut off the long silver flat lead and solder a cable to what's left of it. This will be your negative take-off forward of the batteries. Solder a positive lead to the metal contact inside the barrel. Return the blue section to the barrel and permanently glue with epoxy.


Reinsert the modified barrel back into the Maglite tighten in place with the allen key. Glue a 16mm piezo switch into the space left. Before you glue shorten the legs and solder two leads to the legs. I used 2-part metal epoxy to glue the piezo to the Maglite (Devcon). Run all four leads forward through the convenient hole in the barrel.

So, 2 leads from the switch and the positive and negative leads from the battery.
Then connect the power leads to your protection circuit, and from there to the toggle circuit and whatever LED you want to use. The toggle circuit is made from a few parts; including a 556 timer chip and a logic FET. I used the following circuit. The protection circuit is because the D Cell Li-ion's from Kaidomain don't have their own protection circuits. Space is a premium here so the circuit and PCB are back to back, and go in sideways.


The Maglite head is semi-permanently glued to the body by polyeurathane sealant (Sikaflex Marine). You will not need to open this again.


The lens is 4mm glass glued permanently in place by epoxy putty (Selleys Aqua-Knead-it). The bezel is then sealed to the head by silicone sealant (Silastic). So, no O rings in the head section to leak when you don't want them to. Using silicone for the bezel instead of a stronger glue means it can be 'cracked' open if ever you need to service the front section. I made a couple of wood clamps for this; A square of wood holed with a hole saw and cut in half. Good for an even grip in the vise and won't scratch the finish.



The back end. You need to shorten the spring as in the picture. D Cell Li-ions are slightly longer than normal D Cells. The O ring needs to be upgraded to a thicker 2.5mm one. As the toggle circuit chews a few milliamps I leave the back end slightly cracked to open the circuit and save the batteries. Batteries have a charging bed with leads for both balance charging, and normal fast charging. Again, don't forget they are unprotected so don't mix up the polarity in or out of the torch!



If you prefer a lanyard connection you can always use a hose clamp.

I've made a few torches in my time and this would have to be the most solid. Maglites are a perfect host for a dive torch, and great for heat sink/dissipation, and this one sits in your BC pocket.

Thanks for all your ideas guys, and hope this is of some help to someone.

awesome mod :twothumbs,
now where did you get 4mm glass??????? i want one, no i want 5.

wait, i have 4 D li ion from kd, they are protected, mine are in black wrapper as well, kd also sells unprotected, but they are in blue wrapper.

You probably notices two different bezels in the photos. I've made two of these mods so far; one for a dive buddy and mine. The silver bezel is 4mm glass from the local glazier. I used glass lenses a couple of years ago with overdriven MR16s and this bezel was in my old bits box. The black bezel is actually 6mm Perspex. It's cheaper to buy, easier to work with and stronger, especially in larger diameter (100mm+) torches.

Comes coated in brown wax paper to protect the surface while you work on it. I've cut a thin edge ring of paper off in the photo ready for gluing into the bezel.

6mm is thicker than you need but that's all they had in the shop. The upside is it will probably last to a deeper depth than I can dive...and live!

Thick glass/Perspex is fine if you use the Silastic bezel sealing method. Using this, you don't have to screw the bezel beyond the threads to cover an O ring for waterproofing. The seal is in the threads itself so the bezel can sit prouder on the Maglite.

Interesting you say the black D Cells you got are protected because the ones I got are definitely not. I say this because I use an el-cheapo battery gauge ($3 from Dealextreme) to monitor the voltage when in the charger. Handy little thing and dirt cheap. Trouble is, I left it attached to the charger bed and me being a silly idiot forgot it chews power. Over the next few days it slowly discharged the batteries to 0 volts. I had to bin them because they were permanently damaged through over-discharge.


These are the ones I ordered, in the photo they are blue, but came black;
http://www.kaidomain.com/ProductDetails.aspx?ProductId=2708
Can I ask what is the serial# of your protected D Cell Li-ions? I wasn't aware they could get protected D Cells.

mine are these

http://www.kaidomain.com/ProductDetails.aspx?ProductId=2751

there aren't any numbers or markings on the cells themselves, but pcb is visible on positive end

Very cool mod :twothumbs

The pictures are a little bit too small. The forum allows you to post images up to 800x600, so you can make them larger so that we can actually ready the text within them

OK, here are some of the key pickies enlarged.

I know there have been several threads in the past with the concept in mind of making a Mag 100% waterproof and most all have failed due to the switch boot being the flaw in the design. But it looks like you have it figured out. Good job!

The use of a Piezo switch is a great idea.
I am very new to building dive lights and I know virtually nothing about electronic.
I am building a canister light that will have a mag-lite head.
I am using LED drivers and my battery has protection.

I was wondering what kind of circuit I would need to use the Piezo switch.
Any help would be appreciated.

Marty

The piezo switch is great for underwater use because it is 'bomb-proof', with no moving parts. Not my idea to be honest, it's been around for some years now in this underwater torch game. The downside is it is costly at around $45 each, and you have to connect it to a circuit to use it in a torch.

When you press the piezo it closes the contacts for anything up to half a second, depending on how hard you press it. the harder you press, the longer the contacts close for. So, that means it is a momentary switch. You then have to tranlsate that momentary connection into turning on and off your torch (or cycling through the modes on some of these LED drivers). The way you do this is attach a circuit to it that translates the momentary contact into a press-on/stay-on, press-off/stay-off system. We also need a component that allows the high power needed by our lights to flow without cooking the switch and the circuit it is attached to.

I've been looking around for a ready made toggle circuit for some time now, hopefully small with sub-minature compnents, but the only one I've found is the Polulu switch circuit. I tried it and it does not work with the high currents we need (recommend you don't buy it). If anyone knows of a switch circuit that saves you spending an hour soldering one up yourself then please let us know.

Failing that you have to make one yourself, and the circuit I use is above. Another solution is to program a simple computer chip yourself to do this. For that you need the hardware and software to do this and this is a bit beyond my abilities. The added benefit of this however is you can program your own lighting modes into the chip, not just the off and on.

Also, a piezo in a Maglite fits like a dream.

The popular ones made by Schurter are 16mm barrel diameter with a 20mm top. A Maglite switch hole is 16.5mm...so the 20mm shoulder sits perfectly on top of maglite stopping it from falling through.
http://www.schurterinc.com/pdf/english/drawing_PSE_M_16.pdf

A ring of glue and voila!