Probe a Pushbutton Switch
A pushbutton switch is a type of tactile (meaning touch) switch, which is an on/off switch that is activated when pressure is applied to it (usually by a finger).
The figure shows one type of pushbutton switch. Each of the eight switches is a normally open, momentary single-pole, single-throw (SPST) pushbutton switch. That’s a lot of words just to tell you that this type of switch
- Makes or breaks a connection between two points
- Is normally open, or off (that is, the connection is broken)
- Is temporarily closed, or on (making the connection), when you press its button
- Is off again after you release its button
Note that the pushbutton switch shown has four pins. Inside the switch, the top-left pin is connected to the top-right pin, and the bottom-left pin is connected to the bottom-right pin. These pin pairings just give you two ways to access each side of the switch connection; you are still making or breaking a single connection.
The single make-or-break connection that the pushbutton switch controls is between the top pins and the bottom pins. You can use either one of the top pins for one side of the connection in your circuit and either one of the bottom pins for the other side of the connection in your circuit.