Electrical Engineering › Section Q · Thyristors, operational amplifiers, and power conversion › Topic Q.3
The UJT, the SCS, and field-effect-controlled thyristors
A thyristor is only as good as the circuit that fires it. This topic covers the unijunction devices that generate trigger pulses, the silicon-controlled switch that can be turned off from a gate, and the MOSFET-driven thyristors that need almost no drive at all.
In this topic
- Trigger devices and gate control
- Inside the UJT
- Peak point, negative resistance, valley point
- The UJT relaxation oscillator
- Worked example: timing a UJT oscillator
- Why the resistor has limits
- The programmable UJT
- Worked example: a PUT oscillator
- The silicon-controlled switch
- MOSFET-controlled thyristors
- Common mistakes to avoid
- Key takeaways
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