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 IP3
"- going"
Input Switch


How the circuit works.....

The voltage at the output of this module is +9 volts unless the push to make switch has been pressed. When the switch has been operated, it is said to have been "made" and the output voltage immediately falls to 0 volts. The "pull-up" resistor is there to take the output back up to 9 volts when the switch has been released. This is essential if you connect to "logic" or PIC devices; as they have to see a logic1 (+) or a logic 0 (-) signal. Without the resistor the signal would be floating.
This module is sinking the next stage, as it produces a negative voltage or potential at its output. The arrow's tail on the module indicates this negative voltage. As an example, when you connect up the L.E.D., connect its Anode (+) side via a protection resistor to the positive side of the power supply. By doing this you are making a complete circuit (see OP1 for further reading on this).

 

 

Circuit Diagram

 

 

 

Other examples of switches giving a - going output voltage.