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Topic: Transistor inverter logic... (Read 656 times) previous topic - next topic

cjdelphi



How come i never see "use a pnp transistor" ? Price? Cheaper ti manufacture npn?

MarkT

PNP transistors are slower than NPN, that's why.

(actually there is also historical bias towards strong pull-down logic gates due to TTL families)
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mmcp42

it could well hark back to the fact that early PNP transistors were pretty leaky as they were Geranium based
NPN using Silicon were much better
there are only 10 types of people
them that understands binary
and them that doesn't

MarkT


it could well hark back to the fact that early PNP transistors were pretty leaky as they were Geranium based
NPN using Silicon were much better


Well surely the choice was between silicon PNP and NPN then?  After all the fact that thermionic
valves are all n-type didn't cross over into the semiconductor world...
[ I won't respond to messages, use the forum please ]

mmcp42

nope in the beginning PNP silicon had such lousy gain that you had to use germanium
there are only 10 types of people
them that understands binary
and them that doesn't

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