Yesterday I disassembled an old cellphone to look for some parts which I could use. Besides some buttons, a microphone and a speaker, one particular component caught my attention. I extracted a small vibra motor. Vibra motors are responsible for the vibrating notification your cellphone can alert you with. In general they are just small DC motors. At the top of their shaft they have a weight in the form of a half circle. When the motor spins the weight, it gets out of balance and you experience a vibration.
You also can order those motors online if you don't have a cellphone lying around.
With the motor and an additional LED, I decided to build a toy for my cat.
Usually those little motors work with a 3V power supply. I used a coin cell battery holder for my circuit so I could keep the project really small. The only thing left to do was to attach a 150Ω resistor with a red LED to the circuit. Now the circuit can be placed in a casing. I used a surprise egg plastic casing. Make sure that you seal the casing or stand by when your cat plays with it, so your cat can't accidentally break it open and swallow the parts.
Let's have look at the setup:
Parts (150Ω resistor and LED are missing on that photo)
Circuit in Casing
Here is the circuit diagram of the project:
If you assembled everything correctly, the result should look like this: