Overview
Dreidel, dreidel, dreidel, I made it out of clay
And when it's dry and ready, I'll play with it all daySamuel S. Grossman (lyrics) and Samuel E. Goldfarb (music)
Decorate your dreidels with magic lights this holiday season. These little wireless LED lights are one of the coolest things in Adafruit's catalog. When they get in proximity to a powered induction coil, the lights wirelessly power themselves up and glow! No batteries, controllers, or wires are required.
Put them into your dreidel and the dreidel will light up when it spins over the coil!
This project is an easy and fun one to do with kids. There's no soldering or tricky electronics knowledge required: just a drill press and a little belief in the magical power of physics.
I used the small coil shown above for my project. We also have a larger version that runs on a 24v power supply and can light up your whole table.
If you'd like the no-soldering version of this project, this power supply and screw terminal combo will make it possible to power the smaller version of the coil using only a screwdriver. Use the 5v power supply for the smaller coil or the large 24v power supply for the big coil.
If you're using the smaller coil and aren't afraid of a little soldering, you can power it with an old USB cable. I'll show you how to do this on the next page.
Additional Materials
- Wooden dreidels
- An old picture frame
- Mirror glass spray paint (optional)
- Clear packing tape
- CA glue
- Acrylic paint / decorations for the dreidels
Page last edited December 24, 2024
Text editor powered by tinymce.
How it Works
From Wikipedia:
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.
History
In Faraday's first experimental demonstration (August 29, 1831), he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal transformer). Based on his understanding of electromagnets, he expected that, when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. He saw a transient current, which he called a "wave of electricity", when he connected the wire to the battery and another when he disconnected it. This induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected. Within two months, Faraday found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near the bar magnet with a sliding electrical lead ("Faraday's disk").
Faraday explained electromagnetic induction using a concept he called lines of force. However, scientists at the time widely rejected his theoretical ideas, mainly because they were not formulated mathematically.
Page last edited December 24, 2024
Text editor powered by tinymce.
Powering the Coil
The small coil wants 5v, which is easy to get using any USB cable. I found an old USB mini cable in the bottom of the drawer and decided to upcycle it into my power supply for this project.
Cut the small end off and expose the wires. A good pair of wire strippers is really helpful here.
Normal USB cables have 5 wires inside: look for a red and black wire as well as a few colored data wires. You can just ignore these for this project. Trim them to get them out of the way.
Some USB cables are charge-only cables. If you have a charge-only cable, there will be just 2 wires in there: red and black. You're golden.
Solder the red to the red wire on the coil and the black to the black wire.
Plug in your USB cable to a normal wall socket and hold the coil over your LEDs. When the coil gets close enough, the LEDs light up like magic!
Page last edited December 24, 2024
Text editor powered by tinymce.
Table Assembly
To house the coil, I got an old picture frame from my local Goodwill. I removed the picture and painted the back of the glass with silver mirror-effect spray paint.
It turns out, this paint is slightly conductive! It must have real metal flakes in it. I attached the coil directly to the painted surface with clear packing tape, and it stopped working. The metal in the paint was enough to disrupt the coil's magic from doing it's thing.
Page last edited December 24, 2024
Text editor powered by tinymce.
Dreidel Assembly
Decide where you'd like the LEDs to be placed on your dreidel. For my first prototype I put all the holes right in the center of the four sides and used a different colored LED on each side. This created a "blended" color effect when the dreidel was spun.
For my second prototype I put the four holes at different heights on each side and added all white lights. This created a very interesting effect where all four lights created their own line of light when the dreidel was spun. Watch the video at the beginning of this guide to see the different effects.
I used a vice to hold the dreidels in place and a drill press to drill the holes. I used a 3/8" drill bit, which was the perfect size for the small LEDs. The depth gauge helped me drill the holes to the perfect depth so the tops of the LEDs are flush with the sides of the dreidel.
Paint or decorate your dreidels before putting the lights in, to avoid getting paint on the face of the LED lights.
Once you're happy with the paint job, put a drop of CA glue (krazy glue) into the hole and slide the LED in with the light facing outwards.
If you get too much glue in the hole and in squishes out, remember that CA glue makes a terrific wood finish! Smear it all over the dreidel and it will seal your paint and keep your dreidel looking brand-new for years.
Finish your dreidels by adding your Hebrew letters on each side. I used my Cricut vinyl cutter to cut iridescent stickers that catch the light and reflect beautifully. Here's a file you can upload to the Cricut Design Space, or for $0.99 you can find ready-to-cut files in the Cricut downloads.
Rules of the game
Each player begins with an equal number of game pieces (usually 10–15). The game pieces can be any object, such as chocolate gelt, pennies, raisins, etc.
- To start the game, every participant puts one game piece into the center "pot". Every player also puts one piece into the pot when the pot is empty or there is only one game piece in the pot.
- Each player spins the dreidel once during their turn. Depending on which side is facing up when it stops spinning, the player whose turn it is gives or takes game pieces from the pot:
- If נ (nun) is facing up, the player does nothing.
- If ג (gimel) is facing up, the player gets everything in the pot.
- If ה (hei) is facing up, the player gets half of the pieces in the pot. If there are an odd number of pieces in the pot, the player takes half the pot rounded up to the nearest whole number. If hei is facing up and only one piece is in the pot, the player can either take the piece or not.
- If ש (shin) is facing up, the player adds one of their game pieces to the pot (sometimes accompanied by the chant "shin, shin, put one in"). In some game versions, the player adds three game pieces to the pot, one for each stem of the letter shin (ש).
- If the player is out of pieces, they are either "out" or may ask another player for a "loan".
Page last edited December 24, 2024
Text editor powered by tinymce.
