Thyristor Tester


Posted on Feb 6, 2014

The circuit in the diagram is a very handy tool for rapidly checking all kinds of thyristor (SCR, triac, ). In case of a triac, all four quadrants are tested, which is done with S3, while in case of a standard thyristor, a positive power supply and trigger current need to be set, which is done with S1. The value of resistors R1 and R2 is chosen


Thyristor Tester
Click here to download the full size of the above Circuit.

to obtain a current of about 28 mA, which is more than sufficient for most thyristors. The hold current is determined by R3, and is 125 mA, which is more than adequate to keep the thyristor in conduction after it has been triggered. Since D1 is a red, low-current LED, and D2 a green, low-current LED, it can be seen in a wink in which quadrant the thyristor conducts. Testing is started with S2, and the circuit is reset with S4 after the test has been concluded. Three short lengths of circuit wire terminated into insulated crocodile clips on connector K1 will be found very convenient for linking any kind of thyristor to the circuit. Mind correct connections, though: in the case of a triac, MT1/A1 is linked to earth, the gate to S2 and MT2/A2 to R3; in the case of a standard thyristor, the anode is linked to R3, the cathode to earth, and the gate to S2. If, in a rare case the trigger current needs to be altered, this can be done by changing the value of resistors R1 R3 as appropriate. The trigger current may also be made variable by the use of a variable power supply. If that is done, make sure that the dissipation in the resistors is not exceeded.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Microphone pre-amp
    12v high/low battery monitor
    Mobile Phone Charger with CA3130
    Current-Loop Scr Control
    Simple 2M 6M Transverter Circuit
    Poddwatt: Class-A Stereo Push-Pull EL84 (6BQ5) Vacuum Tube Amplifier
    LA3600 5 Band Equalizer Circuit
    temperature controller using ds1820 and lcd display
    Adding an Inrush Current Reducer to an Astron Linear Power Supply
    Self-excitation - one short brake circuit



    Top