Triac or SCR is a very useful component, although it is not used in all electronic devices or circuits but in some electronic circuits it perform very essential tasks. So it is always good to make a triac tester circuit. You can also test triac/SCR using multimeter but with triac or SCR tester
circuit the testing is much easier as compare to multimeters. So here is a very simple triac tester circuit to test all types of triac/SCR.