Quote:
Originally Posted by 1100 man
The first question that has arisen is that of the FET connections. These are devices I know next to nothing about but it would seem that the drain & source are named from an electron flow point of view. My conclusion is that the source is the more negative one akin to the emitter on a NPN transistor and the drain is the more positive. Would that be correct? They are not marked on the circuit diagram.
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Yes, Source is negative, Drain is Positive.
The probable reason they are not marked on the original schematic is that the 2N3819 could be fitted either way round.
Re the BF256, if you know the manufacturer of the device you have, go by their datasheet, if not, try it and see. The worst that I can see (from the circuit) will happen is a dead FET.
If you can get a J310 FET, they can be fitted either way.