Uni-Junction Transistor (UJT)
A UJT (Uni-junction transistor) is a three- terminal semiconductor device. A UJT has three terminals, namely the emitter(E), base 1(B1) and base 2(B2). UJT act as a switching transistor. UJT have heavily doped P region and lightly doped N region. UJT have two ohmic contacts called the base 1 and base 2. The working of UJT is based on two types; 1. When no voltage is applied at emitter; and 2. When voltage is applied at emitter. 1. Open emitter- No voltage is applied at emitter: Here, B2 is connected to the positive side of VBB and B1 is connected to negative side of VBB. When the voltage VBB is applied, a small current start to flow from the emitter to the base 1. The small current flowing from the emitter to the base 1 is the leakage current (reversed current). This device will not conduct and is known to be in switch-off state. 2. When voltage is applied at emitter: Here, the B2 is inactive. Another voltage VE is connected to the device. Positive side of ...