UJT sawtooth generator
6 parts
The classic sawtooth generator: 10 k charges 120 n toward 12 V until the unijunction's emitter hits the peak-point voltage — 7.47 V, which is η·V_BB + 0.6 V at the default standoff ratio η = 0.6 — then the emitter–B1 path latches, dumps the cap, and the ramp restarts every 1.19 ms (839 Hz). Each dump also fires a 6.1 V spike across the 100 Ω B1 resistor, the pulse real UJT circuits use to trigger thyristors. The UJT is a behavioural negative-resistance latch (fires at η·V_BB + Vf, releases below its 2 mA valley current, 22 Ω fired path); real emitter-junction physics, peak-point current and temperature effects are not modelled.
- V1 12V
- R1 10kΩ
- C1 120nF
- UJT1
- R2 470Ω
- R3 100Ω
