Magnetic Switch Solution
Design the thing that will light up, shake or buzz!
Turn on an LED or a vibration motor with a magnet.
Reed switches are similar to relays, except that they use a permanent magnet instead of a wire coil. This type of switch was invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood. The reed switch is normally open, but when a magnet is brought near the switch it is closes.
Image from http://en.wikipedia.org/wiki/File:Reedswitch.PNG
Reed switches are inexpensive and can be purchased from
Jameco,
mouser,
digikey, and
Tayda Electronics.
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Image from
en.wikipedia.org
Parts
- Breadboard—Jameco
- Wire—Jameco
- Reed Switch —Jameco
- 3V Coin cell battery
- 3V Coin cell battery holder
- Output
- LED
- Motor
- Speaker:
(Your circuit can trigger sound with a few changes:
The 555 is setup as an astable multivibrator operating at a frequency of about 1kHz that produces a shrill noise when switched on. The frequency can be changed by varying the 10K resistor.
Image from www.radioland.net
- Dual Mini Board with 213 Holes Protoboard—RadioShack
- Magnet —Amazon
Instructions
Here is a simple circuit:
But if you wanted to make your own magnetic switch you can. This project was originally created by by Cy Tymony for
Make Magazine Volume 7 page 51:
The paper clip lies across a "spring" of rolled tape or a piece of foam with one end hovering just above the aluminum foil and the other end taped down. When a magnet passes over the switch, it tugs the clip to touch the foil, completing the circuit. Connect a switch to a 3V battery to light an LED, buzzer, or other low-current devices and toys.
How can you use this circuit? Maybe you need to find something in a bag. Wear a ring with a magnet in it. Put your hand in the bag and light up a your printed keyring.
1/8" cube magnets are a great size to use for this.
- Breadboard the circuit first to test it.
- Use a digital caliper to measure your components. Write down the dimensions.
- Freeform solder or use the protoboard to make your design more permanent
- Think about how people look for things or play with objects or are entertained. Follow the steps of the design process, then design the housing that reflects your thought process.
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