AC voltage light dimmers circuit with SCR

Dimmers for the house usually work in one of 2 ways.
Old style dimmers use a variable resistor. As resistance increases, the voltage drops. As someone rightly said, V = IR. While the tension has fallen, you do not really save much energy as the energy is transformed into heat.

Newer style dimmers use the fact that we use and AC power supply and a semiconductor triac called pure, or ’switch to triode alternating current. ” This is similar to a diode or transistor. This type of dimmer is not to reduce tension, but it swich on and off. This is the kind of drive the most commonly used in homes over the past 25 years.

How it works? Our 240-volt AC is nothing but the RMS (root mean square) of the tension that will provide positive to negative, provided in the form of a sine wave.

In Australia, it is provided at 50 Hz (or cycles per second), each half cycle is 1/100th of a second (not 1/120th). How modern dimmer switch works is that it chops a part of the sinusoid at each time the voltage changes from positive to negative. Most of this period (ie the part of 1/100th of a second), the dimmer the bulb. Each period of the sine wave is cut, there is no power being applied to the bulb.

This is a somewhat simplified version of history. Although a triac is used in the circuit, thus is a variable resistor, like the old style dimmer, but it is used to modify the flow of electricity in a capacitor which is used to fire the triac.

There is a 3rd type of dimmer that is most frequently used in commercial applications, for example, lighting of the theater. This method uses an autotransformer instead of a triac. This dims the lights by increasing the voltage from the light circuit. A tap on the mobile autotransformer adjusts the step-down action to mitigate the lights at different levels. This method does not hum or flicker that occurs with triac devices in May.