This is a quick and easy instructable on how to make your own EMF Detector. You can use it to detect electromagnetic fields produced by your electronics. I like how the addition of the piezo buzzer makes it sound like a geiger counter for detecting radiation.
Step 1: Things You Will Need
1. Arduino or other suitable microcontroller.
2. Antenna like this one.
3. 3 Mega Ohm resistor.
4. LED (You can use the on board LED if you would like)
5. Small Piezo Buzzer
6. Battery. I like cylindrical batteries like these but you can use a 9V Battery.
8. Soldering Iron and Solder
9. Screw for attaching antenna.
Step 2: Wire It Up
Simply connect the Piezo Buzzer and LED in parallel between ground and digital pin 11. It doesn't have to be pin 11, just a pin with pwm(pulse width modulation) capabilities. On most Arduino boards, pwm works on digital pins 3, 5, 6, 9, 10, and 11.
Wire a 3 Mega Ohm resistor between ground and analog pin 5 and your antenna to analog pin 5.
If you have an Arduino with solderable contacts for the pins, it is much easier to wire up.