#244 DPDT Toggle Switches
All about double-pole, double-thow toggle switches.
A double-pole switch controls two circuits with a single action.
The double-thow nomenclature indicates that each circuit can be switched between two states.
Example Part: DPDT 2.54mm pitch Switch
Product example: 8x8mm Self-locking Push Button Switch
This is a convenient DPDT switch for PCB construction, having a pin pitch of 2.54mm. Unfortunately, the pin rows are only separated by two pitches (5.08mm), so it is one pitch short of a standard DIP layout. This means it cannot directly plug into a breadboard and span the centre line.
This particular part has the common poles on pins 3 and 6. Other parts may use a different layout; in fact I have come across an identically-looking part with a different (aligned) orientation of the poles. So it is always worth testing before assuming…
The simple circuit described below demonstrates the DPDT toggle switch. The reverse polarities on each pole demonstrate the isolation.
- when switch is “off” (i.e. not pressed), the red LEDs light on each pole
- when switch is “on” (i.e. pressed), the yellow LEDs light on each pole