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    • #8859

        Hi all,

        With the troubles of forum member Bbarry with his transistors, I thought it would be a good idea to test transistors in an easy yet detailed project.

        I have made a video around this which shows it in action : Legacy transistor tester

        It works as follows :

        The silicon diode at the left sets a steady voltage of 0.7 Volts to the potentiometer.

        By rotating the potentiometer, more or less voltage will be applied to the Base of the transistor.

        When the transistor is good, the Collector voltage will drop when the Base voltage rises (turning the potentiometer clockwise).

        If this is not happening, then the transistor is probably faulty.


        This circuit is also great for drawing the transistor characteristics.

        By switching the negative (black) probe from the Collector to the Base and reading the meter with different settings of the potentiometer, you can visualise the Ub and Uc characteristics.

        Try the different transistor blocks and compare the results. Each has it’s own bias resistor (100K, 330K, 680K) and these will influence the behavior of the transistor.

        Many greetings

      • #8863

          Hi Frank,

          This is an especially useful solution that any Lectroneer can avail themselves of.  We all know how legacy transistor blocks’ viability can be questionable.  Thanks very much for this!

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