Quote:
Originally Posted by G6Tanuki
In WWII-era parlance "VT" was "Valve, Transmitting" [and VR was "Valve, Receiving].
Must admit, as time went on and transistors proliferated, I really liked the Dutch "ELEKTOR" magazine's approach to "use whatever generic device you have here, it's not at all critical" .
TUP - Transistor, Universal PNP
TUN - Transistor, Universal, NPN
DUG - Diode, Universal, Germanium
DUS - Diode, Universal. Silicon.
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Although I seem to remember that the American military used 'VT' (standing for 'Vacuum Tube') for all their valve numbers. This caused some nasty confusion where it was least needed.
I liked the Elektor system too. In a lot of cases (as I am sure many of us know) the reason that a particular transistor or diode was used in the prototype of a magazine project was that it was what the designer had on the bench/in the junk box. I am guilty of that too. I'll send out a circuit with a 2N3904 transistor on it. Most likely a BC547 would work just as well, but the 2N3904 is what I have in stock.
I seem to remember reading an article in one of the magazines in the 1970s where the author (correctly in my opinion) stated that most circuits could be built using only 5 types of transistor :
A small-signal NPN (2N3904)
A small-signal PNP (2N3906)
A medum power NPN (BFY50)
A power NPN (2N3055)
An n-channel FET (2N3819).
Obviously there are exceptions, but it's surprising what you can do with just those types).