The 2N2646 is intended for general and industrial triggering and oscillator circuits where circuit economy is of primary importance. lt is a high speed switching device with a low saturation voltage.
Absolute maximum ratings
Power Dissipation 300mW
RMS Emitter Current 50mA
Peak Emitter Current
(Capacitor discharge <10μF) 2A
Emitter Reverse Voltage 30V
Interbase Voltage 35V
Specifications
Intrinsic Standoff Ratio (VBB = 10v) ή 0.69
Interbase Resistance (VBB = 3v, Ie = 0) RBB0 6.7
Emitter Saturation Voltage (VBB = 10v, IE = 50mA) VE(sat) 2
Emitter Reverse Current (VB2E = 30V IB1 = 0) IE0 .001
Peak Point Emitter Current (VBB = 25v) IP 0.8
Valley Point Current (VBB = 20v RB2 = 100R) IV 5
Base-One Peak Pulse Voltage V0B1 8.5
Basic Theory
The unijunction transistor (UJT) has 3 terminals: Emitter (E). Base-one (B1 and Base-two (B2). Between B, and B2 the UJT has a resistance of from 4.7k to 9.1k. In operation the UJT emitter voltage VE is lower than the emitter peak voltage VI. The emitter will be reverse biased and only a small leakage current will flow. When VE equals VI the emitter current will increase enormously. At the same time the emitter-B1 resistance will fail to a very low level.
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