Household Switches

Household switches are quite simple. The standard switch (left) is a single pole, single throw (SPST) switch. When you want two switches to control the same circuit a single pole, double pole (SPDT) switch is used (right). All switches used in complex circuits are combinations of these simple devices.

Knife Switch

Two double-pole, double-throw (DPDT or 2P2T) knife switches. The "knife" makes contact by "cutting" in between two spring-like tabs. These simple switches are more complex than household switches. One benefit is that you can see what state they are in.

Rotary Switch

Although rotary switches can be as simple as a SPST switch, this complex switch has 24 poles and 8 throws (24P8T). The contacts are heavily gold plated and the original price was $577.00

Motorized Cam Operated Switch

Again, a motorized cam could drive a single SPST switch, but this unit controls 10 SPDT microswitches. The cams can be programmed by hand to control any sequence of operations which will continually cycle. This is a 10-gang cam timer.

Closeup of the cam / microswitch interface above.

Motorized Cam Operated Switch

Again, a motorized cam could drive a single SPST switch, but this unit controls 5 SPDT microswitches. The cams can be programmed by hand to control any sequence of operations which will continually cycle. The cycle speed can be changed by replacing the gears. This is a 5-gang cam timer.

Closeup of the cam / microswitch interface above.

Solenoid Stepper Switch - 1P24T

A single pole 24 throw (1P24T) rotary switch which can be incremented one step at a time by driving a solenoid. A second solenoid will reset the position of the switch to the start.

Another view of the above.

Solenoid Stepper Switch - 10P27T

A 10 pole 27 throw (10P27T) rotary switch which can be incremented one step at a time by driving a solenoid. This is the kind of switch that was used extensively in telephone switching before the arrival of solid state circuitry. A number of these were sequenced by the Japanese during WW2 in order to encrypt communications (the Purple machine).

Another view of the above.

Encryption Wheels - Swiss NEMA

A modification of the German ENIGMA machine used to encrypt messages during WW2. Each wheel routes 26 contacts randomly to another 26 contacts at the other side. As each wheel is set the message is routed through a complex maze.