DIY Electrostatic Meters

Static electricity experiments have been around for a long time.

Electrostatic meters are used to detect static electricity. Static electricity is the buildup of charges on surfaces. It can be generated when objects are rubbed together. For example, it can occur when a balloon is rubbed against a wall, or when a plastic pen is rubbed with a piece of paper. A DIY electrostatic meter can be built with a FET. A FET is a special type of transistor used for switching electrical signals. To measure current strength, use a small meter calibrated with a potentiometer. Detect the static electricity with an antenna made of insulated copper wire.

Things You'll Need

• MPF102 FET
• 18-gauge insulated copper wire
• 100k-ohm potentiometer
• 0-1ma meter
• 9V battery
• Battery holder
• Breadboard
• Jumper wire

Instructions

1. Determine which of the FET’s leads are the drain, source, and gate. Insert the chip into the breadboard so all three leads are in separate columns.

2. Insert a jumper wire between the drain and a breadboard row or column that is the ground.
   Strip the insulation from the ends of the 18-gauge wire, and attach it vertically to the gate.

3. Connect the middle lead of the potentiometer to the source. Connect one of its end leads to ground, and the other to a breadboard row or column that is the voltage source. Attach the plus side of the meter to the source, and its minus side to the ground.

4. Connect the battery holder to the voltage source and ground, and then insert the battery inside it. Bring the circuit near an electrostatic source such as a television or computer monitor. Calibrate the meter by turning the potentiometer knob so it does not extend too far right.

Tips & Warnings

• Use solid copper wire for the probe.

• Solder the parts together instead of using a breadboard or a PCB board. The circuit can then be enclosed inside a plastic case that has a small opening for the antenna.

References

• “Alarm, Sensor, and Security Cookbook”; Thomas Petruzzellis; 1993
• “Conceptual Physics”; Paul Hewitt; 2006
• “The Forrest Mims Circuit Scrapbook Volume II”; Forrest Mims; 2000

Resources

• Circuit International: Static Detector Negative Ion Detector
• Science Hobbyist: Ridiculously Sensitive Electric Charge Detector