Basic electronics and electrical tutorials and guides chapter wise fro electrical and electronics engineering students. Best resources for eee, ece students. Tutorials about AC Circuits and AC Circuit Theory. 19 Tutorials about Bipolar Transistor and FET Amplifiers Miscellaneous Electronics Tutorials and Circuits. Triac Tutorial and Basic Principles In the previous tutorial we looked at the construction and operation of the.


Author: Nya Rodriguez
Country: Jamaica
Language: English
Genre: Education
Published: 7 July 2014
Pages: 389
PDF File Size: 30.97 Mb
ePub File Size: 24.11 Mb
ISBN: 257-8-30880-105-6
Downloads: 7538
Price: Free
Uploader: Nya Rodriguez

Download Now

This makes the triac ideal to control a lamp or AC motor load with a very basic triac switching circuit given below.

Http://www.electronics-tutorials.ws/power/triac.html Triac Tutorial and

When SW1 is closed, Gate current electronics tutorials ws applied to the triac from the battery supply VG via resistor R and the triac is driven into full conduction acting like a closed switch and full power is drawn by the lamp from the sinusoidal supply. Of course, the problem with this simple triac switching circuit is electronics tutorials ws we would require an additional positive or negative Gate supply to trigger the triac into conduction.

But we can also trigger the triac using the actual AC supply voltage itself as the gate triggering voltage.


Consider the circuit below. When switch SW1 is open, the triac electronics tutorials ws as an open switch and the lamp passes zero current. As the supply is electronics tutorials ws AC, the triac automatically unlatches at the end of each AC halfcycle as the instantaneous supply voltage and thus the load current briefly falls to zero but re-latches again using the opposite thyristor half on the next half cycle as long as the switch remains closed.

This type of switching control is generally called full-wave control due to the fact that both halves of the sine wave are being controlled. However this time when the switch is connected to position C, electronics tutorials ws diode will prevent the triggering of the gate when MT2 is negative as the diode is reverse biased.

Triac Phase Control Electronics tutorials ws common type of triac switching circuit uses phase control to vary the amount of voltage, and therefore power applied to a load, in this case a motor, for both the positive and negative halves of the input waveform.

This type of AC motor speed control gives a fully variable and linear control because the electronics tutorials ws can be adjusted from zero to the full applied voltage as shown. Triac Phase Control This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply.

Triac Tutorial and

The variable resistor, VR1 electronics tutorials ws used to control the amount of phase shift on the gate of the triac which in turn controls the amount of voltage applied to the motor by turning it ON at different times during the AC cycle.

At the start of each cycle, C1 charges up via the variable resistor, VR1.

Once the triac is triggered into conduction and saturates, it effectively shorts out the gate triggering phase control circuit connected in parallel across it and the triac takes control for the remainder of the half-cycle.

As we have seen above, the triac turns-OFF automatically electronics tutorials ws the end of the half-cycle and the VR1 — C1 triggering process starts again on the next half cycle. This simple triac speed control circuit is suitable for not only AC motor speed control but for lamp dimmers and electronics tutorials ws heater control and in fact is very similar to a triac light dimmer used in many homes.

Triac Tutorial and

However, a commercial triac dimmer should not be used as a motor speed controller as generally triac light dimmers are intended to be used with resistive loads only such as incandescent lamps.

Then we can end this Triac Tutorial by summarising its main points as follows: Electrical AC power control using a Triac is extremely effective when used properly to control resistive type loads such as incandescent lamps, heaters or small universal motors commonly found in portable power electronics tutorials ws and small electronics tutorials ws.


Please remember safety first!. The Diac The DIode AC switch, or Diac for short, is another solid state, three-layer, two-junction semiconductor device but unlike the transistor the Diac electronics tutorials ws no base connection making it a two terminal device, labelled A1 and A2.

Diacs have no control or amplification but act much like a bidirectional switching diode as they can conduct current from either polarity of a electronics tutorials ws AC voltage supply. Then the mean value of the lamp current would be varied by changing the delay time, T between the start of the cycle and the trigger point.

FPGA-Based Embedded System Developer's Guide - A. Arockia Bazil Raj - Google 圖書

But to achieve phase control, two things are needed. One is a variable phase shift circuit usually an RC passive circuitand two, some form of trigger circuit or device that can produce the required gate pulse when the delayed waveform electronics tutorials ws a certain level.

One such solid state semiconductor device that is designed to produce these gate pulses is the Diac. The diac is constructed like a transistor but has no base connection allowing it to be connected into a circuit in either polarity.

The diac symbol and the voltage-current characteristics curves of the diac are given below. However, a electronics tutorials ws triac dimmer should not be used as a motor speed controller as generally triac light dimmers electronics tutorials ws intended to be used with resistive loads only such as incandescent lamps.