Build a Digital Decade Box
Having the right tool makes any job easier. This decade box allows you to select a required resistance with a couple of switches — so no more checking with an ohmmeter to see the actual resistance value.
How to Use a Transistor as a Switch
Whether you need to flash an LED, energize a relay, turn a buzzer or alarm on or off, or invert a voltage level, the NPN transistor switch can easily solve your problem. This article shows you how to use a transistor as a simple SPST switch.