Answer 3

The following circuit controls the bulb using three switches.

SW1 and SW3 are SPDT and are known as "three-way" switches, mainly because they have three terminals. SW2, while electrically a DPDT switch, is usually constructed with four external terminals and is therefore called a "four-way" switch. The circuit can be extended to any number of control positions by inserting additional four-way switches between SW2 and SW3.

Contributor: Naveen PN

Published: September-2002