Test with a multimeter

NPN BJT (BC547)

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Now: Base → emitter (red on B, black on E)

CircuVanta 6000 counts · auto range DCAUTO•)))HOLDFUSE− HOLD LIGHT OFFV⎓V~Ω•)))FmA⎓ mA400 mACOMVΩ Collector (C) 1 C Base (B) 2 B Emitter (E) 3 E
Pin 1: Collector (C) (C) Pin 2: Base (B) (B) Pin 3: Emitter (E) (E)

Red probe Not connectedBlack probe Not connected

Hold the probe and drag it to the tip of a leg. Tapping works too: first pick the probe, then the leg.

Set the range to diode test.

Measure step by step

An NPN transistor is measured like two diodes joined at the base: base to emitter and base to collector in the forward direction. Collector to emitter should read OL in both directions. This test does not measure gain (hFE).

  1. 1Base → emitter (red on B, black on E)
  2. 2Base → collector (red on B, black on C)
  3. 3Emitter → base (reverse)
  4. 4Collector → base (reverse)
  5. 5Collector → emitter
  6. 6Emitter → collector