Harness the power of modern lighting technology by converting a standard lantern torch into an LED torch. LEDs provide the advantage of longer bulb life, reduced power consumption (originally 750mA, now 320mA) and reduced heat. This project uses 32 LEDs which provides slightly more light than stock while using under half the juice.
- 1x 6v Lantern Torch / Flashlight
- 5mm White LEDs. Any multiple of two. I used 32 LEDs for this one.
- 1 Ohm 1/4W Resistors. One resistor required for every two LEDs used.
- Disc shaped wooden or plastic object that fits inside the reflector to mount the LEDs. I used a jar lid that I trimmed down.
- Thin gauge wire.
- Soldering equipment
- Drill, tape and stationary
Remove the lens from your torch. You may need to remove the bulb before you can get the reflector out. Ensure nothings securing the reflector in as it can be a bit delicate and may break if removed with force. In my case, the lens was attached directly to the reflector and had to be removed also.
Find or make a circular disc like object made from a thin wood or plastic that will fit in the reflector. I used a jar lid with the threaded section trimmed off for some bonus kludge points.
Apply a layer of masking tape over your disc and rule a grid that will evenly space your LEDs over its surface. Keep in mind that you need to have an even number of LED mounting holes. Once you're happy with your measurements, use a small drill bit to drill pilot holes. This helps to accurately reproduce your grid on the disc. Drill out the pilot holes with a 5mm bit. I used some sand paper to clean everything up afterwards.
LED pairs are going to be connected in series with a resistor. Each pair will then be wired in parallel. Install a pair of LEDs and bend the legs to connect the positive leg of one LED to the negative leg of the other creating a pair with a single positive and negative leg. Apply some solder to the join to secure the pair together. Continue until all the pairs are installed.
A resistor will be added to limit the current applied to each LED pair ensuring only a safe amount will be supplied. This will ensure your LEDs lives are not tragically cut short and you can enjoy the LED benefit of longer lamp life. Clip the negative leg and resistor leg to around 5mm in size and solder. Repeat for each pair. Although it doesn't matter which way you attach the resistor, I'm a stickler for installing them all in the same orientation. You can now test each LED pair using the 6v battery for the torch.
We now need to connect each LED pair in parallel which basically involves soldering all the positive legs together to make a single positive leg and the same for the negative. Bend each positive leg over to connect to the one next to it, clip them to size and solder them together until only your single vertical positive leg remains.
When connecting the negative legs, ensure you're making the connection after the resistor so you don't bypass it. Adding the resistor raised the height of the negative legs allowing you to make connections over the top of your positive ones easily. Be careful not to accidentally connect any of the negative and positive legs together as your light won't function.
Once all your pairs are connected in parallel and you have a single positive and negative, connect a wire to each and extend these connections. It's not a bad idea to insulate the solder points for these two wires with some tape or heat shrink tube. Test your light with the 6v battery and ensure all the LEDs light up. If they don't, examine the connections to the LEDs that didn't light. Run the two wires through your reflector and secure the disc in with some glue. You now have a completed LED lamp ready for installation.
Wire our new LED lamp into the current circuitry of the torch. A standard lantern torch simply has the battery connected to the globe through a switch. We're going to connect the lamp in the globes place. Cut the wire between the switch and globe terminal as shown in the attached image.
Solder the positive lead from your lamp to the wire connecting to the switch and the negative lead to the wire connecting to the globe terminal (I soldered my to the terminal directly). The globe used to make a connection between the globe socket and terminal (see images) however as he's absent we need to bridge this connection with a piece of wire to complete the circuit. Install your reflector and assemble the torch. Push the button and be smug, you have the Prius of lantern torches.