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Voltage polarity on transistor data sheets

Hi,

I seem to get stuck on the stupidest things.

I've been reading the datasheets for two transistors, the MPSA55 and the KSP55, and I'm curious if the polarity differences for collector current, collector-base voltage, etc are important, because the two transistors are "cross-referenced" on quite a few sites. The data sheets for the transistors are located at:

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So for example, on the MPSA55's datasheet, Vcbo is +60V, and on the KSP55's datasheet, Vcbo is -60V. I would like to know if the sign difference is significant here.

I assure you that I have no intention of using these transistors any time soon, because I know very little about them. However, they could be useful at some point in the future, and I am trying to save myself $6.50 from digikey by ordering them with some other stuff. So this is officially a six dollar question. =)

Thank you very much for your help.

Reply to
longjohnstuartmill
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Actually, longjohnstuartmill misread teh a55 data sheet - it doesn't say

+60, it just says 60, so it's OK. :-)

Cheers! Rich

Reply to
Rich Grise

As both sheets specify them as a PNP transistor, the - sign does not mean anything significant in this case. All one sheet is doing is to put in the - sign to denote the collector is negative inrespect to the emitter for a PNP transistor. Some sheets will put in the - sign for this reason but some will not and expect you to know to hook the collector to the negative side of the power supply in respect to the emitter.

Reply to
Ralph Mowery

Thanks. That's useful information. =) I never saw it explicitly stated anywhere. Maybe that's because everybody knows it automatically...

Heh, my questions are so simple that they're borderline trollish. I think it's partly because I don't know anybody that I could ask in person, and also because I'm trying to learn using only web sites, some old library books (and when I say old I mean they use vacuum tubes), and this newsgroup. But it could also be because I'm not too bright.

Oh well... Eventually I'll either give up or save enough money to take some courses.

Thanks again for your help.

Reply to
longjohnstuartmill

There are lots of things that are done in electronic circuits that the writers are expecting you to know. For example tube filiments are not always shown in the schematics or most likely they are not shown with the other tube elements but you are expected to find them on the schematic grouped with all the filiments connected to the transformer. Same with some ICs . The ones that use a positive and negative voltage may or may not show the power supply leads. Then they may be grouped together and a bunch of capacitors shown with them. You are suspose to know to put the capacitors close to the power pins of each IC.

I had worked with electronic schematics for years and then took a job where I also had to look at electrical blueprints. It took a while before I could follow the simple prints due to the same problem. Just had to learn what I was suspose to know :-)

Reply to
Ralph Mowery

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