Re: How do Atom Computer Ignition modules work?

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June 17, 2015 at 11:41 pm #18309
legendre
Participant
    quote mercuryman:

    Is this a valid test for the D1071’s Hooked 14 volt dc supply to a auto tail light , light to collector and Emitter to negative. Connected 300 ohm resistor from collector to base( had .7 volt on base). The light burned dim and 8.1 volts was across the D1071. Should the light burn bright in the test.

    Add ammeter in series between the supply + terminal and the light bulb, then take all of the same voltage measurements as well as the current reading and we’ll know for sure, BUT..

    Take a look at the 2SD1071 datasheet. The saturation voltage of 2.0V is reached at a base current of 15mA. Your base current is 27mA (8.1V / 300 = 0.027) which is way higher than the 15mA required to saturate.

    But you still read a 8.1V drop across the D1071 – it is +not+ saturated, and it +is+ a fake. Put an accurate DC ammeter in series with the bulb, I bet you measure about 595mA – or just over 1/2 amp.. right? That would be an hfe of ~22 as in my fakes.

    Get your money back, I did.