What is silicon controlled rectifier (SCR)?

Silicon Controlled Rectifier is a four-layer current-controlling device, which is used in devices like dimmers. These are used in device that require the control of high power and high voltage. The working of the whole region of the SCR circuit predominantly relies upon the method of its triggering.

What is a silicon-controlled rectifier?

A device with widespread application in industry is the silicon-controlled rectifier. It is used for speed control of motors, for dimming of lights, for control of heating furnaces, and in general wherever control of power is needed. Recall that in a rectifier, current starts to flow immediately when the diode becomes forward-biased.

What is a thyristor dimmer?

A thyristor dimmer, also known as a silicon-controlled rectifier (SCR) dimmer, is an electronic device used to control the brightness or intensity of lighting or the speed of electric motors in various applications. It works by adjusting the voltage supplied to the load, such as an incandescent lamp or an AC motor, to control the output.

How does a capacitor VCAP work?

To understand the operation of the circuit we first assume there is no charge on capacitor C5 and node Vcap is near the positive supply voltage. A square wave is applied at Vin and is capacitively coupled to the emitter of Q3. The falling edge of the input waveform induces a slug of charge equal to the change in voltage times the value of C4.

What happens when a capacitor discharges through a put?

The capacitor discharges through the PUT. When the voltage across the capacitor goes below valley point voltage (Vv) the PUT reverts to its OFF initial condition and the capacitor C T will stop discharging. The capacitor will start to charge again and the cycle is repeated.

What happens when a capacitor exceeds peak voltage?

When the voltage across the capacitor exceeds the peak voltage (Vp) the PUT is triggered and goes into negative resistance mode and this creates a low resistance path from anode (A) to cathode (K). The capacitor discharges through the PUT.