#244 DPDT Toggle Switches

All about double-pole, double-throw (DPDT) latching toggle switches.

Notes

A double-pole switch controls two circuits with a single action.

The double-throw 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…

I’ve attached some pin headers to make a breadboard-compatible switch:

Test Circuit

The simple circuit described below demonstrates the DPDT toggle switch. The reverse polarities on each pole demonstrate the isolation.

Operation:

• 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

Construction

Credits and References

• Switches
• Switch - wikipedia
• 8x8mm Self-locking Push Button Switch - example part from aliexpress seller.
• ..as mentioned on my blog