Just as lamps can be connected in series or parallel in an electronic circuit, switches can also be connected in series or parallel. For example, two circuits that each use a pair of SPST switches to turn a lamp on or off. In the first circuit, the switches are wired in series. In the second, the switches are wired in parallel.
The interesting thing to note about wiring switches in series is that both switches must be closed in order to complete the circuit. A great example of switches wired in series is in the typical nuclear-war movie, where two people must flip a switch in order to launch the missiles. Switches wired in series means that Denzel Washington and Gene Hackman must both agree to launch the missiles.
When switches are wired in parallel, closing either switch will complete the circuit. Thus, parallel switches are often used when you want the convenience of controlling a circuit from two different locations. If the nuclear missile switches were wired in parallel, either Denzel Washington or Gene Hackman could fire the missiles.
How to build a series switch circuit
This electronics project presents a simple project that uses two switches to open or close a circuit that lights a lamp. The switches are wired in series, so both switches must be closed to light the lamp.
How to build a parallel switch circuit
In this electronics project, you build a simple circuit that uses two switches wired in parallel to control a lamp. Because the switches are wired in parallel, the lamp will light if either of the switches is closed.
