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A comment on LGP-30 found in basement, the same model of drum computer programmed by “Mel”. Parent comment

Re:LGP-30 found in basement, the same model of drum computer... by Gordonjcp on Tuesday November 08, 2022 @03:19AM (#33517052)
> Leads to some goofy schematic choices like the negative voltages being at the top of the schematic pages because it lines up better when compared with a tube based design.

I'm guessing this is because it was using early germanium transistors which would most likely be PNP. It was a long time before NPN transistors became the "default", because they were easier to make in silicon which came along later.

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Re:LGP-30 found in basement, the same model of drum computer... by monocasa on Tuesday November 08, 2022 @04:30AM (#33517469)
Right on the money, they're 2N1301 germanium PNP transistors for the most part.
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Re:LGP-30 found in basement, the same model of drum computer... by retrac on Tuesday November 08, 2022 @11:45AM (#33521078)
Probably right. It's actually still normal/correct to draw a PNP circuit between negative rail and ground with the negative supply at the top. Schematics should convey how the engineer thinks about the circuit, and inputs come in the top and left and outputs exit at the bottom/right. Except no one really designs PNP-oriented circuits with negative supply voltages these days because eugh.
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