Lantern Torch LED Conversion

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Introduction: Lantern Torch LED Conversion

About: A tech and gadget enthusiast who enjoys building and creating DIY projects. Check out my projects and tutorials on Instructables and x2Jiggy.com!
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. I've made a video showing the basic steps involved in making the project. You'll be building a small LED light and installing it in the reflector. This light is then connected to the circuitry in the torch so it operates as per normal. If you're keen, take a few minutes to view then continue on to the detailed instructions. If you enjoyed the video, please consider subscribing to my youtube channel as this helps towards producing more videos and projects.



 

Step 1: Equipment

Parts:
- 1x 6v Lantern Torch / Flashlight (Amazon)
- 5mm White LEDs ( Amazon / DealExtreme ) Any multiple of two. I used 32 LEDs for this one.
- 1 Ohm 1/4W Resistors ( Amazon ) 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.

*Affiliate links provided to suitable products on Amazon.com and DealExtreme.com

Tools:
- Soldering equipment
- Drill, tape and stationary

Step 2: Disassemble Reflector

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.

Step 3: LED Mounting Holes

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.

Step 4: Install LEDs

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.

Step 5: Complete LED Light

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.

Step 6: Install Lamp

We need to 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.

More projects and videos at x2Jiggy.com. You can also follow my twitter feed @x2Jiggy.

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57 Comments

user

This will definitely help me with my Boat spotlight.
Thanks !

but does it boast the same focus as it had previously....i don't think so....i would consider the same task being done with 26k cmd leds in a tighter arrangement so that it fits deeper down the reflector...also you have a plane reflector...not the ones with tiny individual rectangular reflectors arranged within the reflector surface ...i aave one and will modify it but with some design inputs from my side too...

If I wanted to run a configuration of this off the 12 system on my truck, what kind of resistors should i use so not to blow the leds?

nice idea,

i have an old rechargeable lantern that has busted 4.8volts halogen light bulb, i think i can convert it to this kind of design.. i want to use a smd hi intensity single led bulb the one used for gun flashlight!!

Is it still possible without the reflector? Cause when I opened my old flashlight, it was broken. Is there anything I can do? In exception of getting a new reflector or buying new one.

Are you using a rechargeable 6volt battery or Alkaline Battery?

See my POWER PACKED LED FLASHLIGHT

which uses a rechargeable 6 volts 4.5 Amps leak proof lead acid Battery. The Charging is done outside the light casing with a 6 volt charger. Published:Aug 8, 2010.
Its the same game with a different name?

1 reply

Just a standard 6v spring terminal lantern battery. You weren't kidding, that flashlight is power packed! Plenty of LEDs there. Nice touch with the rechargeable battery.

Nice work, looks like a project for me.... but I wouldn't be smug about owning a prius lol

1 reply

lool True good project. wish one day I can make one I love LEDs things this for me as well look like a project specially because I dont know NOTHING about electrics lol. Good Work! May be one day I will try this.

Now this is a sexy flashlight.

I'm looking at www.superbrightleds.com and there are white led's that have a luminous Intensity of 18,000 millicandelas. They have a typical forward voltage of 3.4 volts with a max of 4 volts. Would a resistor still be necessary ? I don't pretend to understand this but it seems to me that a pair of led's in series that operate at 6.8 volts each and i'm only providing 6 volt to the pair i should be under the typical voltage and surely be under the max voltage of 4 volts.

9 replies

You must ALWAYS use a resitor with LEDs, or it'll burn itself with time (or very fast).
I recommend you to use an online tool for the design, and try different (parallel and series) setups:

http://ledz.com/?p=zz.led.resistor.calculator

Hmmm, I am lead (led) to believe otherwise, by persons that know on various 12v and electronics forums,that is one DOESNT always need to use resistors...but hey ! tell me Im wrong , I like to learn !

One of the big benefits of LED lighting is long life and LEDs are very sensitive to increases in current. Unless you can guarantee the current supplied (usually by building or purchasing a regulated driver) it's good practice to add a resistor or risk an early death for your LEDs.

Some people choose not to use a resistor when their input voltage matches the LED forward voltage, however without a resistor a small change in voltage can produce a large change in current. Resistors are cheap, easy to install and when you add the resistor a change in voltage will produce a proportional change in current protecting your LEDs.

In-ter-esting ! As a digression , the situation I had in mind was a string of leds that were to be fitted to a car as day running lights . I inquired about resistors and was told that since the forward voltage etc ,blah,blah, (what you said above !) I didnt need resistance added.
I have been worried that the current change produced by the voltage range on a 1990s land rover, roughly 12 and a half to 14 and a half volts dc would indicate the need for a resistor and since I cannot find out what even using online calculators I havent fitted them.

If you have a source of power (like a D cell battery) that never exceeds the max forward voltage of the LED you can do without the resistor.

But a automotive electrical system has a constantly varying output as noted in other post here. If I wanted to use LEDs from a automotive electrical system I would buy or build a circuit that limited the voltage and as well preferably limited the current going to the LEDs and included spike protection.

Years ago I connected an oscilloscope to a car battery and noticed that the ignition coil was inserting high voltage spikes into the 12 volt systems of over 1K volt every time the spark plug fired. This was in the days where they used "points" before they switched to electronic ignition systems. So an older car could be really rough on LEDs and other electronics. Most car radios and common auto electronics have built in spike protection to prevent this problem.

Has anyone ever connected an oscilloscope to a modern electronic ignition car to check things like this?

Diode for spikes, cap across neg/pos supply for smoothing ? In my case Im talking diesel,traditional diesel,always diesel.Not common rail or electronic injection . And yeah , the current variation caused by that 2v range....well,doesnt sound a lot until you look at it as a percentage of total.

To respond to your situation, yes I think the diode and cap would work for a diesel.
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But I "think" it would NOT be enough for a gasoline engine (of any type). Spikes and short over voltage situations often only "weaken" the transistor based components like IC chips and diodes which then fail after some unknown time period. That is why that after lightning damage to your home, your home electronics continue to fail for months afterwards.
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The more times the electronics are subjected to surges the weaker they become. Since a "spark ignition" system, if in bad condition, "could" hammer the diode and other electronics in you car thousands of times a minute I think I would install 24 volt MOVs to reduce the strength of any surges before they reach your surge protection circuitry in this type of car.
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MOVs are devices that short out above a specific voltage and revert to a high ohm resistor when the voltage drops. They look like large (even giant) ceramic disk capacitors. They also wear out after X number of high power spikes and have to be replaced. In the case of an ignition system I don't think the power would be high enough to make this a problem.
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The time the MOV conducts is limited to the duration of the spike plus a few milliseconds. In the case of spark ignition caused spikes, these only last for a few milliseconds and the voltage during that spike is limited to 24 volts.
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Normally 24 volts would "burn out" any 12 volt electronic component. But because this "burn out" is caused by heat generated relative to the duration of the over voltage--"usually" the heat generated by this over voltage during the few milliseconds or less that the spark induced voltage is over 24 volts is not enough to damage the device. But given the thousands of times a minute that your electronics could be subjected to this over voltage it could be possible that the heat build up over time could destroy the LED or other circuitry.
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I don't think this would happen in a car where the ignition system was in good shape, but if it had problems and was feeding large spikes back into the 12 volt system it could. Also late model cars (which are dripping with electronics) must have installed something to prevent this or designed it in such a way that this was not a problem.
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thanks for all the replies. as this project uses a 6 volt DC battery i guess my question was answered.

If the power supply outputs less than the LED's maximum voltage, you don't need a resistor. But if the voltage drops too much you will lose a lot of light. So it's best to use a higher voltage supply and drop the excess voltage through resistors. The more voltage goes through the resistors compared to the LED(s), the wider voltage range it will tolerate without changing brightness too much. But you waste more power and dissipate more heat that way.