LED Lightsaber

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This is a simple LED-lit DIY lightsaber -- it is made of PVC and polycarbonate tubing, and uses a magnet and a reed switch to switch the LEDs off and on. It's pretty easy to make, reasonably robust, and looks great! This was the first project in the Monthly Make It.

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Check out our Instructional Video

You can also see these instructions as an Instructable.


Materials

If you get your kit from us, you will have the following prepared materials. Notes on how to prepare them yourself are in the next steps.

Left

The Handle + Blade

1) An 8" long piece of 3/4" diameter schedule 40 PVC pipe with two 1.5" long cuts at right angles to each other made on one of the ends.

2) A 1.5" long piece of 1" diameter schedule 40 PVC pipe with a cut made through one side.

3) A 3/4" piece of 1" diameter schedule 40 PVC pipe with a cut made through one side and a 3/8" hole drilled into the other side.

4) A 1.25" piece of 1/2" PVC pipe with a cut made through one side.

5) A 3/4" PVC end-cap

6) A 22" long 5/8" outer diameter, 1/2" inner diameter polycarbonate tube, with one end closed.

7) A length of Vinyl Electrical Tape, approximately 61cm (2 feet)

The Circuit

1) 2 AA batteries.

2) A long 2xAA battery holder.

3) A reed switch plus a 4" length of wire. We have soldered the wire to one side of the reed switch, and attached a female quick disconnect terminal to the other end of this wire, as well as a male quick-disconnect terminal on the other side of the reed switch. -- http://www.mouser.com/search/ProductDetail.aspx?R=...

4) A Strand of LEDs soldered in parallel -- 22 inches long with 1 LED per inch.

5) A 1/4" translucent diffusing tube to hold the LED strand. We get this along with the LED strands from China. If you take apart an LED sword you'll find one of these. Otherwise a bunch of drinking straws will do in a pinch.

Kit Building Instructions

1 Put the Batteries in the Battery Pack

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What to Do

The first thing we need to do is to put the batteries in the battery pack.

Make sure to put the batteries in the correct way -- with the flat (-) sides up towards the spring and the black wire.

Why

Our LED strand needs about 3 volts to light up, so we use a battery pack which holds 2 1.5 volt AA batteries together in series.

2 Test the LED Strand

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What To Do

Your LED strand has 2 terminals. Your battery pack has 2 terminals. Very gently and loosely connect the LED terminals to the battery pack terminals. If the LEDs light up when both connections are made, then you have the correct orientation. If they do not, try the other way.

Why?

LEDs are light-emitting diodes. This means that they only allow electrical current to flow through them in one direction.

You can also tell which side of the LED strand is the positive side by looking closely at the individual LEDs. LEDs will have two small pieces of metal inside of them connected to the two leads. The positive lead will generally be a longer leg on the outside connected to a smaller piece of metal on the inside, and vice-versa for the negative lead.

When you are testing, make sure that the metal parts of the separate connections don't accidentally touch -- if they do, you will cause a short circuit, the LEDs will not turn on, and the whole thing will begin to heat up.

Troubleshooting

If you can't get the LEDs to light up, no matter which side you make the connections on, check the following:

1) Make sure your batteries are in correctly

2) Check for a short-circuit. The whole circuit basically has two sides -- power and ground. The red wire + positive leg of each LED make up one side. The black wire + the negative leg of each LED make up the other. If any part of the positive side of the circuit is touching any part of the negative side, you will have a short circuit. Make sure no LED legs are crossing in the strand, and that the terminals are separate from each other.

3 Attach the Reed Switch

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How The Switch Works

Now your lightsaber should be lit up. This is great! But we don't want it to always be on. In order to control whether the circuit is off or on, we will use a special switch called a reed switch.

A reed switch is a magnetically controlled switch. It consists of two pieces of magnetic conductive material separated by an infinitesimal distance inside of a sealed chamber. When near a magnetic field, these pieces of material get pulled into contact with each other, connecting the two ends of the reed switch (and completing the circuit.)

What To Do

You should have a complete circuit with the red wire from your battery pack connected to the positive leg of the LED strand, and the black wire of your battery pack connected to the negative leg.

You will need to disconnect one of these connections. It doesn't matter which one, but the photographs in the instructions have us disconnecting the black wire, so it's easiest if you do that as well.

Once you've disconnected this wire, you'll have two free terminals, one male, one female, to attach the reed switch to. You want to attach the reed switch between these two terminals, so that the wire connected to the reed switch is attached to the LED strand and the other side of the reed switch is connected to the battery pack.

4 Test Your Circuit

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The Final Circuit

This is a complete circuit, with a switch in the middle. If everything is behaving correctly, you should be able to turn the LEDs on by holding your magnet near the reed switch.

Your circuit should have one of the wires from the battery pack attached to your reed switch. There should be another length of wire coming from the other side of the reed switch and attaching to the LED strand. And the other side of the LED strand should be attached back to the battery pack.

Troubleshooting

If it doesn't work, try moving the magnet around the reed switch -- it might work better or worse from certain angles and distances.

If it still doesn't work, try taking the reed switch out and just reconnecting the LEDs straight to the battery pack. If this causes the LEDs to light up, plug the reed switch back in (careful to avoid short-circuits) and try again. If you do this a few times and it definitely doesn't work, then you probably have a broken reed switch and will need to replace it.

Otherwise the most likely culprits are the same as they were before -- misplaced batteries or a short circuit. Check for both of these problems. Remember that if your project doesn't work and starts to heat up significantly you almost certainly have a short circuit. If so, you should remove power immediately before searching for the short.

5 Affix the Reed Switch to the Battery Pack

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Protecting the Reed Switch

The reed switch is a somewhat fragile part, and we want to make sure it isn't damaged inside the handle of our lightsaber when we swing it around. The best way to do this is to attach it to the battery pack. We do this with electrical tape, or a tiny bit of hot glue.

The reed switch consists of a black plastic enclosure with two metal leads coming off of each side. The battery pack has 2 wire holders molded into it -- small clips on the back side which can be used to guide the wires.

Where to Attach

You will want to attach the reed switch so that the metal lead attached to the wire (which is attached to the LED strand) is placed inside the wire holder nearest the LEDs. It will not fit snugly, but you can line up the plastic enclosure so that it touches the wire holder.

Tape It Down

Once you've positioned the reed switch, you will want to tape it down. Tape it in two spots -- around the point where the wire and the reed switch lead are soldered together, and around the middle. If it feels lose, feel free to tape it on the other side as well.

Why?

We have three goals here. We want to cover up the small amounts of exposed metal in the connections to prevent short-circuits. We want to anchor the reed switch in two places to the battery pack so that it can't rotate or be easily bent or twisted inside of the lightsaber handle. And we want to make sure that the leads of the reed switch are up against the back of the battery holder so they cannot be bent.

Bending the reed switch leads is the easiest way to break the reed switch.

6 Prepare the Polycarbonate Blade to Fit in the Handle

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Assembling the Blade

The polycarbonate tube will be the "blade" of the lightsaber. The LED strand, inside of a smaller, diffusive plastic tube, will fit inside the polycarbonate tubing. The bottom of the polycarbonate tube will fit into the 3/4" diameter PVC handle.

The problem is that the polycarbonate tubing is too small to fit snugly into the PVC. In order to have it snugly held in the handle, we will attach a short length of 1/2" diameter PVC around the bottom of the blade to increase its diameter.

What To Do

The further problem here is that the 1/2" PVC is not large enough to fit around the polycarbonate tubing. We have cut a slot in the 1/2" PVC which allows you to pull the pipe apart and fit it snugly around the polycarbonate.

This might be a little bit tricky, but you can do it, and once you do you will want to align the bottom of the polycarbonate tube with the bottom of the PVC so that they are flush.

7 Slide Magnet Holder onto the Handle

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Assembling the Handle

The handle of the lightsaber will consist of the 8" length of 3/4" diameter PVC with two 1" diameter PVC collars slipped around it

The larger collar will function as a clamp to hold the blade in place.

The Magnet Holder

The second, smaller of these collars has a hole drilled in it. This is the magnet-holder and slider. This will fit on the handle and be able to slide up and down freely. By moving the slider up and down we will move the magnet around the handle. The proximity of the magnet to the reed switch on the battery pack inside of the handle will determine whether the lightsaber is off or on.

What To Do

It is significantly easier to put these collars on from the top side of the handle with the slits cut into it, because you can fold these slits inward to fit the collars around it. Because of this, we will put the collars on first before we insert the blade.

Start by sliding the magnet holder onto the handle and then most of the way down.

8 Slide the Larger 1" Collar onto the Handle

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What To Do

Next you'll slide the larger 1" diameter PVC length down the handle. This larger length will function as a clamp to hold the polycarbonate blade in place.

9 Insert the Blade Into the Handle

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Connect the Blade

Now you can insert the polycarbonate tube blade into the PVC handle. The slits which separate the top of the PVC handle can be pushed or pried open so that you can fit the collar into the handle.

How?

Push the blade+collar down into the handle so that the collar on the blade is at least flush with, and possibly a tiny bit below, the top of the handle.

10 Secure the Blade in the Handle with the Collar

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Now you can slide the larger PVC collar up to the top of the handle so that it covers the joint between the handle and the blade and clamps it down firmly.

Slide the magnet holder up to the top as well.

11 Tape the Circuit

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Now that we've built the circuit and the handle, it's time to combine them! But first, before we do that, we need to prepare the circuit by covering up all of our exposed metal connections with a little bit of vinyl electrical tape. This will prevent the connections from accidentally touching each other and causing a short-circuit when we insert the circuit into the handle.

Where to Tape?

The two connections that you will need to tape up are the quick disconnect terminals where the LED strand attaches to the battery pack and reed switch.

12 Combine the Circuit and the Body

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Insert the Blade into the Handle

Now we need to slide the whole circuit into the lightsaber body through the bottom of the handle.

When you are sliding the battery pack into the handle, be careful with reed switch -- it should fit in snugly without you having to use too much force.

Push the battery pack in as far as it can easily go.

Troubleshooting

If you find that the red insulation on the quick disconnect terminal extends too far from the body of the battery pack to fit into the handle, you can gently smoosh it a bit, using your fingers or a pair of pliers. You should not need to smoosh it very much at all.

13 Cap the Handle

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Loose Battery Pack?

The battery pack should fit in quite snugly. Even so, you might find that it can move around slightly inside the handle. This will move the reed switch around and make it harder for you to know where the magnet needs to be to turn the lightsaber on.

What To Do

In order to prevent the battery pack and reed switch from sliding down the handle, you can fill the space at the bottom of the handle with a few pieces of ripped and crumpled-up paper.

After you do this, put the PVC endcap on the bottom to close the handle.

14 Calibrate your Magnet Slider

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Warning!

This next step is a bit fiddly -- be patient and you can make it work!

How It Works

We now have the circuit of our lightsaber safe and snug inside the body. We have a sliding magnet-holder that we can rotate and slide up and down the handle.

Place Magnet in Holder

The next step is to insert the magnet into the hole in the magnet-holder and figure out a good spot for it to live.

Because of very small irregularities in the size of the magnets and the holes we've drilled, sometimes your magnet will fit perfectly snugly into the hole in the magnet holder. Sometimes it will want to fall out. If it wants to fall out, you can hold it in place with a small piece of tape.

Find the On/Off Spot

Once the magnet is in the holder, you will want to slowly slide and rotate the magnet holder up and down the handle. You will find a bunch of spots where it turns on and off. You will want to find a spot where it is on, but turns off with a rotation or a very small amount of up and down movement. This is where the magnet holder is going to sit on the handle.

15 Tape the Handle

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This next step is entirely optional, but we find it to be an easy and pretty nice looking way to limit the area of motion of the slider.

Find the "Off" Spot

Now that the lightsaber is on and can be turned off with a very small motion, slide the magnet holder ever so slightly up or down the handle so that the lights turn off.

Tape the Handle

Using a bit of electrical tape, wrap the handle so that the slider cannot move any further in that direction.

If you slid the slider up the handle to turn the blade off, wrap from the top of the slider to the collar around the blade. If you slid the slider down the handle, wrap from the bottom of the slider to the endcap.

Find the "On" Spot

Now slide the slider back so that the blade is on again. Wrap the other section of the handle in tape.

You should have a small area bracketed in black electrical tape where the magnet holder can slide up and down to easily turn the lightsaber off and on.

16 Test your Lightsaber

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You should be able to turn the lightsaber off and on by twisting the handle slightly. Awesome!

17 Sand the Blade

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You're pretty much done!

What To Do

There's one more optional step you can do that we think looks quite nice. The blade of your lightsaber is a length of clear polycarbonate tube. Inside of the tube you can see the inner tube and the LED strand, and it's relatively apparent that the blade consists of a number of discrete LEDs.

Why?

In order to mask this, and make the blade look more like a continuous light, you can sand the outside of the polycarbonate tube. By sanding the tube you create lots of tiny scratches and abrasions that reflect the light in lots of different directions when it hits the edge. This makes the tube translucent instead of transparent and diffuses the light from the LEDs more evenly.

See the photos for a comparison.

Licensing

This documentation describes Open Hardware and is licensed under the CERN OHL v.1.2.

You may distribute and modify this documentation under the terms of CERN OHL v.1.2. (http://ohwr.org/cernohl).

This documentation is distributed without any express or implied warranty, including of merchantability, satisfactory quality, and fitness for a particular purpose.