transistors

An Interesting Two-Transistor Relay Timer

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I came across the printed circuit board for this circuit completely by accident. It looked like an interesting and clever little design, and I had more than enough suitable parts lying around in my component drawers, including a pile of spare relays. So I decided to build one and measure what it could actually do. … Read more

Effortless Component Testing

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Anyone working with electronics will eventually hold a component that you need to identify—what it is, how its legs connect, if it’s the right value, or whether it works at all. Testing with a multimeter A knowledgeable person can learn a lot even with a basic ohm-meter. Some multimeters include diode-test or transistor current gain … Read more