- on Miscellaneous Electronics
- Published in issue 7/2000 on page 0
Using zener diodes and varistors
There is no such thing as complete protection against overvoltage damage due to a lightning strike. However, the risk of a valuable piece of equipment being burned out during a thunderstorm can be strongly reduced with the aid of a relatively simple and inexpensive bit of circuitry.Excessive voltages due to a lightning strike can force their way into a piece of electronic equipment in a variety of ways. They can travel via the telephone cable, an antenna cable or the mains wiring, or simply through the earth. The mains network is especially at risk in the latter case, since its neutral and protective earth leads are after all connected directly to the earth.