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Continuity tester

Bench build · Transistors and thyristors · Beginner · about 15 minutes

Beeps on a closed circuit. Touch the probes across a wire, fuse or track: if it conducts, base current flows through 10 kΩ into the transistor, which switches the buzzer on. An open circuit stays silent.

Continuity tester: the finished build running on the simulator's bench

Build it in the labGuided build, test sheet and fault finding, free in your browser.

Parts list

Test procedure

Each test has an expected value and a pass range, like a factory test sheet:

  1. Probes touching
  2. Probes apart

How it works

What it does: Beeps on a closed circuit.

Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.

Background

The cheapest useful tool on a bench; still faster than reading a meter for checking cables.

More builds: transistors and thyristors