programmable unijunction transistor (PUT)

A three-terminal thyristor that, when biased with two external resistors and a voltage source, can provide a negative-resistance characteristic similar to the characteristic of a unijunction transistor.

NOTE The negative-resistance characteristics are controlled by the resistor and voltage values.

Graphic symbol:

PUT with bias resistors

NOTE B1, B2, and E are the equivalent unijunction terminals with interbase resistance r_BB = R₁ + R₂ and intrinsic standoff ratio η = R₁/(R₁ + R₂).

References