How to test UJT with Digital multimeter?

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How to test UJT with Digital multimeter?

A uni junction transistor (UJT) is an electronic semiconductor device that has only one junction.

The UJT has three terminals: an emitter (E) and two bases (B1 and B2). The base is formed by lightly doped n-type bar of silicon.

Two ohmic contacts B1 and B2 are attached at its ends. The emitter is of p-type and it is heavily doped.

The resistance between B1 and B2 when the emitter is open-circuit is called inter base resistance.

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The original uni junction transistor, or UJT, is a simple device that is essentially a bar of N type semiconductor material into which P type material has been diffused somewhere along its length, defining the device parameter .

The 2N2646 is the most commonly used version of the UJT.

The complementary uni junction transistor, or CUJT, that is a bar of P type semiconductor material into which N type material has been diffused somewhere along its length, defining the device parameter .

The 2N6114 is one version of the CUJT.

HOW TO TEST UJT WITH DMM?

STEP-1.

…Select DMM to Diode Mode
Connect DMM positive test lead to Emitter UJT 2N2646 Pdf Details: UJT-2N2646-datasheet & Circuits
………….DMM Negative test lead to Base-1 = Display reading shows .650v
………….DMM Negative test lead to base-2 = Display reading shows .735v

STEP-2.
Connect DMM Negative test lead to Emitter How to use the Digital multimeter?

DMM positive test lead to Base-1 OL DMM READING SHOWS open
DMM positive test lead to Base-2 OL open
DMM Negative test lead to Base-1 0.874v
DMM Negative test lead to Base-2
DMM Positive test lead to Base -1 0.947v or (947 mV).

Verification:

If you get reading in forward bias as 0000 or OL or 1, and in reverse bias as 0000 (or) low values the the DEVICE can be FAULTY and needs replacement.