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 ...

A switch turns the circuit on or off by completing ... A circuit diagram helps electrical engineers know what to build. Try building simple circuits with your friends and draw diagrams to match ...

You can easily adapt this idea if you need a simple touch switch. Though we imagine this circuit wouldn’t work well if you were in a quiet environment. We suspect 50 or 60 Hz hum is coupling ...