Triac Heater Control Circuit

The triggering parameters are.

Triac heater control circuit.

The trigger circuit is achieved using an unijuntion transistor ujt that introduces a conduction angle on the triac. The moment the sine curve exceeds the above specific voltage level the diac quits carrying out and the triac is turned off. How the triac diac ac controller works the set up of the circuit is pretty standard as the the wiring is very similar to the ones which are normally employed in ordinary light dimmer switch circuits. While designing a triac control circuit its gate triggering parameters become crucial.

Triac gate triggering current igt gate triggering voltage vgt and gate latching current il. The heater control circuit works off stable 9 volt dc supply which may be derived from the mains supply using a standard ac mains adaptor 100ma at 9v or using a traditional capacitive voltage divider assembly. Here we have used the triac to turn on and off an ac load through a push button. Note ca3140 ic2 is highly sensitive to electrostatic discharge esd.

When a triac is used in an electric heater driving circuit a quick blow fuse with a current rating greater than that of the heater but less than the maximum current rating of the triac provides adequate protection. The minimum gate current required to turn on a triac is called gate triggering current igt. This heat control using thermistor and triac circuit is designed to control the temperature of a room either by using a heat source such as an electric oven heating element or by using a fan or any cooling device. Let us look into a simple triac switching circuit to understand how it works practically.

You can find such power circuits elsewhere in this website. A triac can be used to give variable ac power control by using a phase delayed switching technique in which the triac is triggered part way through each half cycle. The standard triac and diacset up can be seen for implementing the basic switching of the triac. Given that the load or the heater in this instance is linked in series with the triac the load also switches off and on in keeping with the triac.