build yourself a simple continuity tester

A simple yet accurate automatic regulated 6/12/24 volt lead-acid battery charger circuit is explained in this article. The circuit switches off the current to the battery as soon as the battery reaches full charge. An illuminated LED at the...

This is a simple single-zone burglar alarm circuit. Its features include automatic exit and entry delays and a timed bell/siren cut-off. It is designed to be used with the usual types of normally-closed input devices such as magnetic reed...

A portable four dimmer switch circuit is illustrated in Figure 8, featuring a four-speed brightness adjustment. When switches S1, S2, and S3 are all closed, the lamp operates at its brightest setting. When S1 and S2 are closed while...

MIDI data is transmitted between instruments using a current loop, and an opto-isolator (6N139) is employed to convert this current loop into TTL pulses. The circuit utilizes the 6N139 opto-isolator to separate the MIDI signal from the receiving device, ensuring...

A phototransistor detects daylight. At dusk, it stops conducting, and Rl biases Q2, activating Kl, which turns on the light. At dawn, Ql begins to conduct, cutting off Q2. Kl deactivates, and the light turns off. The circuit utilizes a...

This circuit is a simple analog multiplier. The operation of the circuit can be understood by considering A2 as a controlled gain amplifier. It involves components such as an analog multiplier, a log-antilog circuit, and a summing junction, along...