Here is a great collection of touch switch circuits. A touch switch is an electronic device that enables us to control a circuit by simply touching a sensor. Simple touch switch circuit with 4011 – ...

Master these simple circuits and you'll be ready ... the circuit is 'open' so no current can flow. Flicking the switch to the 'on' position closes the circuit so that current can flow.

It's all well and good having a perfect, simple circuit but it it includes a switch, it will only work if the switch is in the on position meaning the circuit is closed. You can learn more about ...