For this easy STEM project, we’ll make a fun doorbell. We’ll use a few household items and an electromagnet, along with several other Snap Circuits pieces.
This project and all Geek Pack Hack activities must be undertaken with a suitable adult completing their own risk assessment and supervising their children at all times.
We originally made this doorbell to deck out one of our boys’ blanket forts.
One of the most magical parts of childhood is letting your creativity run wild.
It’s fascinating to watch kids blur the line between fantasy and reality. They get completely wrapped up in their own imaginary worlds playing dress up, engaging in sandbox construction with toy bulldozers and backhoes, or wearing a doctor’s stethoscope and glasses frames as their sibling gets his third check-up of the day.
In our house, forts are serious business. They appear to spring up here and there, now and then, and generally when we least expect it. Each new fort comes with new components: blankets, boxes, tables, chairs, couches, rope, sticks…
Every new fort is more complex than the previous one. Inside features include cozy sleeping areas, organized shelving for books, cubbies for toys, and various defense mechanisms.
As far as we know, this is the first time anyone has built a doorbell for a kids’ fort!
We’ll explain how an electromagnet works, and we’ll show you how we engineered this easy STEM project so your kids can deck out their forts too.
Here’s everything you need to get ringing!
You can check out our video tutorial here and subscribe to our YouTube channel to keep up with new projects.
The boys also had a surprise to give Dad when he came by for a visit. We’ll explain everything below as well (but we can’t give away the surprise!)
The first thing you need to know is that electrical current running through a wire actually creates a magnetic field.
How an electromagnet works
What happens if you create a coil of wire and connect it to a power source like a battery? It creates a bigger magnetic field inside the coil because of all of the little magnetic fields around each individual loop of wire.
An electromagnet has a metal core, which by itself isn’t a magnet. However, when the electromagnet is turned on, the magnetic orientation of the metal atoms line up. This makes the magnet even stronger.
Supplies for this easy STEM project
Snap Circuits Extreme pieces including the electromagnet, battery packs, connector pieces, and jumper wires.
Four AA batteries
Steps to build this easy STEM project
Step 1: Build the clothespin switch
We start by tightly winding copper wire around each leg of a clothespin at the end where the wooden legs are pressed together. Make sure there is good contact between the copper wire on each leg of the clothespin.
Now, in its resting position, the clothespin conducts electricity from one leg to the other.
We’ll design the doorbell so that, when nobody is at the door, the circuit is complete. With current flowing, the magnetized electromagnet holds onto a metal spoon.
When people come to visit, they press on the clothespin. That breaks the circuit, and that the electromagnet lets go of the spoon.
In the picture below, you can see that copper is tightly wound around each leg of the clothespin where they press together. Each copper wire then runs to a jumper wire.
We attached the copper wire to the jumper wire by bending the wire into a small loop that fit over the snap at the end of the jumper wire. We then pressed down a single snap piece on top to sandwich the copper wire in the middle.
Step 2: Wire up the circuit
Using Snap Circuits connector pieces, connect one contact of the electromagnet to a battery pack. Connect the other contact of the battery pack to the second battery pack.
Then, connect the last free battery contact to one of the jumper wires connected to the clothespin switch. The other jumper wire from the clothespin switch connects to the remaining contact on the electromagnet.
Step 3: Arrange the spoon and pot
Almost there! Now you just have to suspend the spoon from a position above the pot and place the electromagnet several inches away from the pot.
That way, when you press the clothespin, it will break the circuit. The electromagnet will let go of the spoon so that the spoon swings back to hit the pot.
Here’s how we tested it out.
When we set up the doorbell on the box fort, we attached the circuit to the side of the box.
We taped a hanger to the top of the box so that the hanger extended out far enough for the spoon to swing out and hit the pot, which we placed below the end of the hanger.
It’s actually possible to make your own electromagnet. Deceptively Educational has a great project tutorial that shows you how it’s done.
Frugal Fun for Boys and Girls has another mind-bogglingly cool project for exploring electromagnetism by building an electromagnetic train.
Check out all of our cool engineering projects.
We also have a helpful basic electronics page that teaches skills such as how to use a breadboard and multimeter.
If you try out this project, please let us know how it went! Where did you put your doorbell? Are there other projects you’d like us to build? Please leave us a comment!