Community Kids' Build: Safer Rainbow LED Throwies

Coventry Makerspace took part in the Coventry Festival of Imagineers this weekend - and these LED throwies were a great make for kids! Full credit for the LED throwie of course has to go to Q-Branch. We modified the components a little to suit our purpose, and using rainbow LEDs took them to the next level!

These throwies are perfect for a public demonstration to get kids into making. They are easy, accessible, quick to make - and above all, very, very fun. As well as allowing the children to create something awe-inspiring, there is a quite a bit of stealth education in there too ;-) The kids couldn't get enough of them, and while we did explain the street-art roots of the throwies, the children treasured them far too much to throw them!

Step 1: Gather Materials

You will need:

• Rainbow LEDs
• CR2032 button batteries
• Electrical insulating tape
• Ferrite magnets
• We also used Makerspace stickers (Instructable coming soon!)

Please see safety notes for an explanation why we have changed the materials from the original throwie...

Quantities really will depend upon how many you are making, particularly if you are organising a community build. But all of the components can be purchased in bulk with good quantity discounts available.

You won't need any tools or equipment, other than a pair of scissors!

Step 2: Safety Notes

As with any activity, there are some risks that you need to be aware of. It's not about 'health and safety gone mad', it's about being aware of the risks so you can reduce and mitigate them so far as possible. We made sure that all children we worked with were old enough to understand that the throwies were not toys, and that they and their parents understood the safety advice issued. We also modified the throwies to reduce risk:

• We ensured that we used insulating tape to wrap the batteries to ensure that there was no danger of batteries ending up touching. Incorrectly stored batteries are a fire risk.
• Batteries are a risk to children if swallowed. Not just because of choking hazard, but because it can set up an electrical current, producing a build-up of sodium hydroxide internally that results in burns and catastrophic bleed. For this project we ensured that the throwies were well wrapped, making them harder to dismantle and swallow, but also educated the children that the throwies are not toys and not edible!
• The magnets in the original throwies are rare-earth (neodymium) magnets. These pose a pinch risk, a severe risk to children if ingested, can be dangerous to those with pacemakers and some other medical equipment, and are also a risk to electronics and data equipment. Because we were working with children and the general public, we chose to use weaker ferrite magnets to reduce these risks.

Step 3: How to Power Your LED!

The first step is to provide power to your LED. The LED has two legs (the proper name is leads) - one is longer, one shorter. It is really, really important to connect them to the battery the right way round! If you attach them the wrong way round, it is possible that it will ruin the LED completely, though in our experience that didn't really happen. But the LED will certainly not light up!

The long lead is positive (+). It is called the anode.

The shorter lead is negative (-). It is called the cathode.

The battery also has a positive and a negative. In batteries, these are called terminals. On the batteries that we are using, the positive terminal is the flat side and the rim, the negative terminal is the underside.

So our first step is to slide the battery between the LED leads the correct way around, so that the LED lights up.

Step 4: Wrap the Throwie

Next, take some insulating electrical tape and wrap tightly once around the battery, to hold the LED leads in place. If they are not held in place properly, the LED will not stay lit! Leave a tail of tape ready to add the magnet in the next step.

You will know if you have done this correctly, because your LED will already be lit up! We are using rainbow LEDs, so it will be flashing and changing colours.

Rainbow LEDs work because they have three different LEDs inside them. They are red, green and blue (sometimes shortened to RGB). These are the primary colours, and all of the other colours are produced by the three LEDs lighting up in different combinations and at different strengths. If you look directly down the LED you can see this happening.

Sometimes the LEDs will have three leads and you will be able to program them to show different colours at different times. The LEDs we are using have a circuit built in (called an IC or integrated circuit) so they are already programmed to flash different colours in a sequence.

Step 5: Add a Magnet... and a Sticker!

Add a ferrite magnet to the back of the bundle and wrap securely. Finish with a makerspace sticker and your throwie is ready!

Because the ferrite magnet is weaker than the rare earth magnets used in the original, they do not stick so well when thrown over large distances, but they work just great over shorter distances! They are safer for kids than the original (though not suitable for children younger than 7) and get kids interested in making as well as teaching them a few of the basics.

We talk a little more about our community outreach in this instructable. We believe it is incredibly important for all makerspaces to get out and about in their communities, if you are thinking of doing it then go for it! It is great fun and very rewarding.