Introduction: Light-Up Minecraft Torch Using a Joule Thief
For everybody who’s ever wanted to make their own light-up Minecraft torch, and would like to play around with some fun electronics in the process, this Instructables project is for you! The electronics are explained well enough (and with links to everything needed) that somebody with absolutely zero electronics experience should be able to make this joule thief and torch.
Why a Minecraft torch?
The Minecraft torch is a real recognizable symbol of the Minecraft game, and I think having one that actually lights up is a lot more exciting than one that doesn’t. And, it’s probably obvious that I really enjoy Minecraft – I also made a Minecraft-themed candle-powered paper carousel and a Mooshroom hat. Plus, it keeps the monsters from spawning nearby!
Why a joule thief?
A joule thief is basically a relatively simple circuit that allows somebody to use “dead” batteries to power something that requires more voltage than the battery has left (it sacrifices current for increased voltage). So, it’s a great way to re-use dead batteries, and learn some electronics in the process! The circuit typically includes an LED, which is lit up by the dead battery. In this Instructables project, I use a joule thief to power three orange LEDs on a breadboard, which all conveniently fit inside of the torch.
Why a breadboard?
Most of the Instructables projects on making a joule thief require soldering (because for people trained in electronics, this isn’t a big deal and produces solid connections between wires). But for a beginner who hasn’t soldered, it’s much easier to use a breadboard. (I wanted this project to be super novice-friendly.) Additionally, it's a lot easier to include multiple LEDs in the joule thief circuit when doing it on a breadboard.
I am not an electronics person by education or training, but I am slowly learning! I’d like to give special thanks to my father, who is an electronics engineer, and my husband, who dabbles in electronics, for much help in figuring out how to adapt the joule thief circuit to the breadboard for this project (and searching for toroids in Akihabara, Tokyo with me). Thanks for all your help!
Also, thanks to these other Instructables projects on making a joule thief:
Step 1: Materials You’ll Need
You’ll need these electronics materials to make the joule thief circuit – note that most of these items are linked directly to the product page on Jameco Electronics:
- Battery holder for one AA battery with wires that are at least 3 inches long
- General purpose transistor, 2N3904 NPN
- Tiny breadboard. The one I use measures 1.9” by 1.3” and has 170 holes. It fits in the Minecraft torch design I give in this Instructables project.
- Slide switch with 3 pins that fit in the breadboard
- Three ultra yellow LEDs. You could use other LEDs instead, but these are the exact ones I used in this project so I know they work.
- Jumper wire kit or insulated wires and wire strippers
- 1K Ohm resistor
- Common mode choke inductor from Digi-Key (through-hole) (this is basically a toroid bead with two wires wound around it). Other through-hole common mode chokes should work fine — I picked this one because it has long wire ends (to easily go in the breadboard) and I tested it so I know it works.
- Alternatively, you could make an inductor like this using enamel-coated magnet wire, 20 gauge or larger gauge (smaller diameter)
(two different colors is ideal)and a sharp knife or fine sandpaper to remove the enamel on the ends, and a toroid inductor (which is a toroid bead with one wire wound around it, which will be removed) or a round ferrite toroid (also called a toroid bead — it has no wires wound around it).
- A round ferrite toroid can be salvaged from a compact fluorescent light bulb by following this video (but be careful not to release the mercury in the bulb!). This should only be done with adult assistance.
- Alternatively, you could make an inductor like this using enamel-coated magnet wire, 20 gauge or larger gauge (smaller diameter)
You’ll also need these other common items that you probably have lying around your home already to make the rest of the light-up Minecraft torch:
- Utility knife
- Pen or pencil
- Glue. A toothpick is also recommended to spread the glue and insert it into small crevices.
- Piece of corrugated cardboard at least 17 cm by 19 cm. (I used an old, long, rectangular FedEx box for this.)
- Adhesive Velcro strip to attach the breadboard and battery pack to the cardboard interior of the torch. I used Velcro so I could remove the breadboard/battery pack easily if I wanted to, but you could permanently attach them to the cardboard using epoxy or super glue (with adult assistance).
- Small paperclip
- Small, sharp knife
- Printer and paper
Step 2: Making the Inductor
If you’re using a common mode choke inductor (like the one from Digi-Key linked above), you can skip this step.
If you’re making the inductor using magnet wire and a toroid inductor that only has one wire wound around it, start by unwinding the wire on the toroid inductor. See the pictures in this step for how to do this. (If the inductor only has one wire wound around it, it will have two metal prongs — the inductor needed for this project must have two wires wound around it, giving it four metal prongs.) Once the wire is removed and you are left with the toroid bead, you can wind new magnet wire around the bead as described in the next part of this step.
If you’re making the inductor using magnet wire and a round ferrite toroid (that has no wire around it), start by cutting two lengths of magnet wire, each the same length and around 70 cm long. (If possible, use two different colors of magnet wire.) Twist 2 to 3 cm of the ends of the wires together. Next wind the wire around the toroid, through the opening in the middle and around the sides (leaving about 5 cm to 10 cm of wire “tail” with the ends twisted together). See the pictures for details. While you wind the toroid, do not let the wires overlap each other (keep the two wires side-by-side, and do not wind them over wire already wound on the toroid). Wind the toroid tightly until you get back to where you started winding it. (It doesn’t matter how many loops you make exactly – in the pictures, you can see I made an inductor with 12 loops [paired], and later I re-did the wire on this toroid bead with higher gauge wire to get 14 loops on it, but there’s a lot of flexibility in what will make the circuit work.) Once at the beginning, cut all four wires so that they have around 5 cm of wire loose. Then use fine sandpaper or carefully use a sharp knife to remove the enamel coating on the last 1 cm of the wires.
Step 3: Making the Joule Thief
Brief overview of the circuit
As mentioned earlier, a joule thief is basically a relatively simple circuit that allows somebody to use “dead” batteries to power something that requires more voltage than the battery has left (it sacrifices current for increased voltage). In this Instructables project, a dead battery is used to power three yellow LEDs. Current first flows from the battery through one of the wires of the toroid inductor, which creates an electromagnetic field (EMF). From the toroid inductor’s wire, the current then flows through the resistor and the transistor.
Transistors are basically like a type of switch, and when the current goes through the transistor (specifically to the base and out of the emitter), this causes the transistor to switch and let current go through the other wire of the toroid inductor (traveling specifically through the collector and emitter of the transistor). When the current goes through the other wire of the toroid inductor, it goes through the wire in the opposite direction compared to the first wire, which means the EMFs made in the two wires oppose each other. This opposition decreases the current and causes the transistor to switch, again only allowing current to go through the original wire in the toroid (to the transistor’s base and out the emitter). But then this switches on the other path in the transistor (allowing current to flow in the collector and out the emitter), which switches itself off due to the opposing EMFs in the toroid, etc. This whole process causes the circuit to oscillate, which generates a higher voltage (at the expense of current) and powers the LEDs.
Assembling the circuit
The order in which you assemble the circuit doesn’t really matter (although it’s best to attach the battery last since it’s hard to know what the off position of the switch is). Here I’ll walk through assembling the circuit based on the order shown in the pictures above. This breadboard doesn’t have labeled holes, but, holding the breadboard so that the dividing groove goes up and down, I will refer to the columns as A–J (going from left to right, continuing across the groove) and the rows as numbered 1–17 (going from top to bottom). (Note that it doesn’t matter which end is “top” — it works either way.)
- First insert the four metal prongs of the inductor into the breadboard. To do this, look closely at the inductor — two of the four prongs will eventually be connected to the battery. These two prongs must be from the different wires on the toroid and from opposite ends of it. Take these two prongs and put them in row 16, somewhere between columns A and D (I put mine in hole 16A and 16C). Take the other two prongs (which should also be from different wires on the toroid and from opposite ends of it) and place one in hole 10C and one in hole 11D (it doesn’t matter which prong goes in which hole, and which exact hole they’re in as long as they’re in those rows). See the pictures for details.
- How can you tell the wires apart? If you are using a common mode choke inductor, it is easy to tell which are different wires since one wire is wound around one half of the inductor, and the other wire is wound around the other half. If you wound your own inductor, I recommend using two different-colored wires or marking the tips of the different wires, such as by using a permanent marker, so it’s easier to tell the two wires apart.
- The inductor in the pictures: The inductor used in the pictures in this step is a common mode choke inductor (purchased pre-wound). I also tested the circuit with the inductor made in step 2 and it worked fine, but I just ended up buying and using the common mode choke inductor.
- Why use a resistor? The resistor in this circuit is important to include because it protects the transistor.
For those of you who like that kind of stuff, I've included an oscilloscope image of the circuit (it's the last picture in this step) -- it was taken from collector to emitter. Enjoy the pretty square wave!
If the LEDs don’t light up when you turn on the circuit, there are some things you can try:
- Make sure that the position and orientation of all of the wires is correct. Go through the step-by-step directions above, and the pictures, to check this. Be especially careful when checking the orientation of the wires on the inductor, LEDs, and transistor, as they are easy to do incorrectly.
- Make sure all of the connections in the holes are good. In particular, check the battery pack wires and inductor wires for this.
- Make sure the inductor is wound properly. Check out step 2 for tips on this.
Step 4: Making the Torch’s Flame
I specially made a torch flame for this Instructable that includes the top part of the torch’s flame — you can see this top part in the game, but I’ve never seen it in a real-life version of the torch, and I wanted to include it.
Print it out
To make the torch flame, start by printing the torch flame PDF in this step. Refer to the arrows for how to fold the different parts together as you go through this step.
Cut it out
Cut the out the flame from the print-out, making sure to leave the white tabs (they’ll be used for gluing). You can cut out the hand-drawn arrows and refer to them in the PDF itself. Take your time carefully cutting everything else.
Fold the four separate sides of the flame, as shown in the pictures. Then fold each of the white tabs backwards, towards the interior of the flame (except for the four tabs on the bottom – leave those unfolded). Next fold the sides of the flame faces to give them ridges – see the pictures for where to do this folding.
Once you’ve folded it into the right shapes, and can see how the sides will be attached to each other, start carefully gluing it together (using the tabs). Start with a face on one end and work your way around the sides of the flame to the other end. Look at the arrows in the PDF and the pictures to see how to glue everything together using the tabs. I recommend using a toothpick to reach those hard-to-reach crevices with glue. Do not glue the tabs on the bottom.
Step 5: Making the Torch’s Wooden Base
The folding for this is much easier than making the torch’s flame, so enjoy!
Print it out
To make the torch’s wooden base, start by printing the PDF in this step. (The bottom square will cover the underside of the bottom of the wood base.)
Cut it out
Cut out the wooden base from the print-out, making sure to leave the white tabs (they’ll be used for gluing). Then cut out a small flap, which will be how you can access the inside of the torch – this is the edge that does not have a white tab (see the pictures).
Fold between the four separate sides of the wood base, as shown in the pictures. Then fold each of the white tabs backwards, towards the interior of the wooden base.
Making the cardboard interior
On a piece of cardboard, use a ruler and pen or pencil to make two long lines that are 18.25 cm apart. Between these lines, and going perpendicular to them, make five lines that are spaced 4.06 cm apart from each other. See the pictures for details. Using the utility knife (so you get clean cuts) and ruler, cut out the large rectangle that encompasses the lines. Then, along the lines that are 4.06 cm apart, use the utility knife and ruler to cut the lines, but not all the way – leave the back side of the cardboard intact.
You’ll next want to cut a small flap which will be how you can access the inside of the torch. On the wood base print-out, this is the edge that does not have a white tab — you can lay the print out on top of the cardboard to see where the flap will end up. To make the access flap, you should go to one of the edge sides of the cardboard and cut a line across the side that is 2.25 cm from the top, and then another line 9.2 cm from the top – see the pictures for details. Cut all the way through the cardboard.
Making the latch
You can make a simple latch that seals the cardboard flap shut. To do this, take a paperclip, unfold it and cut off part of it as shown in the pictures above. Then orient the cut-up paperclip so that the cut part goes down into an open groove of the cardboard, and the rounded part sticks out through the edge of the cardboard. Use a knife to open part of the edge of the cardboard so the rounded part of the paperclip can easily slide up and down inside the cardboard flap. Then slide the paperclip into place as you planned — when the paperclip is up, the flap is “unlocked,” and when the paperclip slides down, it should go into the groove on the bottom part of the cardboard, “locking” the flap shut in place.
Step 6: Attaching the Joule Thief Circuit
You’ll next attach the breadboard and battery pack to the inside of the cardboard frame you just made. You can use epoxy or super glue (with adult supervision) to attach the circuit to the cardboard, or, if you want to be able to remove the circuit at some point, you can use adhesive-backed Velcro to attach the circuit. Because I want to be able to remove the circuit, I used adhesive-backed Velcro.
Open up the cardboard frame so you are looking at the interior side. Where you made the access flap, attach the battery case to the cardboard. This will make it easy to open the torch and access/replace the battery when needed. Then, next to the battery case (on the left), attach the breadboard in place. Make sure that the LEDs are pointing up, that the parts are positioned so that you can completely close the flap (without bumping the switch, etc.), and that you can easily access the switch when you just open the flap from the outside.
Tip: Check again to make sure the joule thief still works, lighting up the LEDs, since you’ve been moving it around a lot! There could be some loose connections that need to be fixed.
Step 7: Attaching the Print-Outs to the Cardboard
Fold the cardboard into its torch shape (with the four sides coming together) and place a few pieces of tape on the inside to hold the sides together while you glue on the paper exterior. Then attach the flame to the top of the torch. Carefully line a thin layer of glue on the inside of the four bottom white tabs, and then lay it over the top of the cardboard frame — it should nicely fit around the cardboard. Hold it on the cardboard a moment to let them glue together.
Then figure out how the wooden base print-out will fit around the cardboard frame. Identify where the access flap will go. (The square sticking out on the base print-out should cover the bottom of the torch.) Glue the print-out on the access flap first because it is most important that this part is lined up correctly. Then glue the rest of the wooden base print-out on the cardboard (using a thin layer of glue) — make sure to glue the tabs for the bottom square before gluing the sides around it.
Step 8: Enjoy Your Light-Up Joule Thief-Based Minecraft Torch!
Enjoy showing off your Minecraft torch! You can carry it around with other Minecraft gear, or use it as a “green” nightlight, reusing all of your “dead” batteries. Enjoy its warm yellow glow, and be happy that it keeps monsters from spawning nearby!
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