Maglite LED Conversion
Turn a Maglite into a LED FlashlightBy Jack Arcade
Assembly Time: 2 hours
Flashlights are always useful especially if you like to camp. Out in the woods, when you are away from your iPhone flashlight, a Mini Maglite comes in real handy. Now, what if you hate its yellow color and carrying extra batteries? What if you want a white color for your flashlight and a longer battery life? Sound exciting? Let's make one.
Required tools and components:
(1) 3mm Nylon Spacer
(1) 10-Foot 24AWG Solid Bus Bar Wire
(1) 0805 0.22µF SMT Capacitor
(1) 1206 1µF Multilayer Capacitor
(1) Schottky Diode SOD-523F Package
(1) LED Driver IC, TSOT23-5 Package
(1) 22µH Inductor, 1210 Package
(1) White LED, T1.75 Package
(1) 12Ω Resistor, 0805 Package
(1) Printed Circuit Board
Mini Maglite Flashlight
Fine Tip Soldering Iron
Solder Paste or Liquid Flux
Tapered Reamer or #12 (4.8mm) Drill Bit and Drill Motor
Project BuildThis project requires SMT soldering skills and quite a bit of patience to build it. If you have not done surface mount soldering before, practice surface mount soldering first. It took me a bit longer to solder as I didn't use all the proper equipment for SMT soldering.
To get started, dismantle the head of the Mini Maglite and pull off the bulb by applying some force as it might be stiffly mounted.
Once you have all the parts with you, figure out the capacitance of C1 and C2 using a multimeter. When distinguishing parts, keep in mind the resistor, inductor and IC are very distinct. Figuring out the terminals of the diode could be challenging though. You could either use the multimeter to determine the terminals of the diode or simply use a magnifying glass – just find the faint silver line on the diode, which should be the cathode, or the negative terminal.
SolderingUse solder paste, solder flux and a soldering iron with a bevel tip to solder the parts perfectly. As the PCB is very small, you will need delicate hands and some patience while soldering.
Soldering the LED could be challenging as you need to keep some distance (0.1") between the LED base and the top surface of the PCB. Use a thin cardboard as mentioned in the instructions to do it. The PCB doesn't show the terminals of the LED but the instructions do. The cathode (shorter lead) of the LED is closer to the J1 on the PCB, thus install and solder in that fashion.
AssemblyAfter you solder the 24-gauge wires, make sure the total length of your assembled kit matches with that of the original Mini Maglite LED. The length needs to match the original length so as to properly close the focus control and lens cap. Make sure to use the spacer so the inductor doesn't get damaged while you adjust the focus.
Make sure everything is properly aligned and that you drill an optimum hole so that the LED doesn't slide against the body of the Mini Maglite (otherwise it gets caught to the surface and might twist the 24-gauge wire leads). Don't rush in assembling the Mini Maglite – take your sweet time doing it.
It was fun building – even though I had to do it twice. My first attempt with SMT soldering did not go well but after some practice it came together. This will surely be a useful flashlight – I think it will provide you with a constant current drive, giving you a constant light output independent of the battery voltage. And, you won't need to carry that extra set of batteries as your Mini Maglite's life expectancy just increased!
Jack Arcade earned his master's degree in Mechanical Engineering from Santa Clara University. He specializes in the design and control of robots. Jack's interests include traveling, camping, trekking, river rafting, bungee jumping and mountain climbing.