scr tester

Posted on Feb 5, 2014

Although you don`t find SCR and Triac in all electronic equipment, this does not mean that both are not important components. You need to learn how to test it so that when you come across one in the future you will know if it is good or bad during troubleshooting. You can test these components using meters but with the SCR/Triac tester you will fi

scr tester
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nd that it is easier to test as compare to using Multimeter. Before I start describing how to build this tester, I guess that it is important to know some of the basic operation of SCR and Triac. SCR stands for silicon-controlled rectifier (or semiconductor-controlled rectifier). It is a four-layer solid state device having an input control terminal (gate-G), an output terminal (anode-A) and a terminal common to both input and output (cathode-C or Kathode-A). It generally operates as an AC switch for lighting and heating control. In the normal "off" state, the SCR restricts current to the leakage current. When the gate-to-cathode voltage exceeds a certain threshold, the device will turns "on" and conducts current. The device will remain in the "on" state even after gate current is removed so long as current through the device remains above the holding current. Once the current falls below the holding current for an appropriate period of time, the device will switch "off". The SCR can be found in switch mode power supplies (SMPS). For your information not all SMPS use SCR. The TRIAC is a three-terminal device similar in construction and operation to the SCR. The TRIAC controls and conducts current flow during both alternations of an ac cycle, instead of only one. Both the SCR and the TRIAC have a gate lead. However, in the TRIAC the lead on the same side as the gate is "main terminal 1-MT1, T1 or even A1, " and the lead...

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