re mysterious mosfet in article qug sinn g rave larc nasa gov kludge grissom larc nasa gov scott dorsey writes i have a mosfet pulled out of a trygon power supply for which i have no manual it s a motorola part with a date code and the number which the motorola folks assure me is a house number which they can t help me with any suggestions from folks out there i can t put it on a curve tracer to try to get an equivalent since it s completely shot scott since your mosfet is a vintage it s probably not a very good one by today s standards if you have an idea about its voltage and current ratings e g vdc a you can probably get away with replacing it with anything with better specs early mosfets had a gate source voltage rating of approximately vdcmax and they would usually turn completely on at vdc otherwise mosfets are not really mysterious they re more or less voltage controlled current sources if the mosfet in your circuit is used as an open loop voltage controlled current source you may have to experiment with various gain altering techniques bill willis willisw coe nw clemson edu
