IDing the pin-outs on a TO92 case...

By day 2 or 3 now, I am getting more comfortable with my schematics/PCB layout software. So, I went back and re-did the schematics for my mixer input amp section, so that it better imports the connections into my matching PCB software. This "turns on" the trace connection helping thingy.

It worls pretty slick. As you add comonents to the PCB layout, when you give them the name that matched a component in the linked schematic, you can click a pin on the PCB and the other pins it connect to highlight. Works great. Except for this ONE component, lmao...

two components, actually, a matched set of NPN and PNP transistors. I went to mouser's website for component information, like lead spacing and component dimensions and stuff. The PNP is a BC560C, the NPN is a BC550C. I'm assuming I'll use the "standard" TO92 case versions.

in the Mouser catalog page, AND the manufacturers adobe PDF datasheets, orienting the flat edge to the right, the collector is the bottom pin, on both transistors.

Question: since mouser and the data sheets only identified the Collector pin, what order are the other two pins? I was assuming base in the middle, 'cos it "looks" in the middle on schematics representations of transistors...so, after Collector is ID'd and you orient the case accordingly...does it go Collector, Base, Emitter or Colector, Emitter Base?

Question #2: as a PCB component for trace layout, I grabbed "TO92" semiconductor for these two. Once linked to the schematic, the "trace helper" thing is ID'ing the pins differently...

On the one, its highliting connections to be "collector, emitter, base", with the ID of the colector pin the same as the data sheets. (this is the PNP)

On the NPN, its saying the base is in the same place, but switching the collector and emitter, as if to say "Emitter colector base", with teh base matching the othee one's location.

I can positively ID the collecor from teh data sheets, and i assume theres a convention for the order of the other two...CEB likely...but then, why is it showing the collecor in teh middle on the NPN case?? I assumed the emitter ws ALWAYS the arrrow pin on schematics, with any transistor.

does the software know something abuot pinouts standard location in to92 cases I cant get off the data sheets???

EDIT: on the schematic, the npn and pnp are runnign as a matched pair, with bases and collectors tied together...

> i assume theres a convention for the order of the other two..

Yes. Actually two conventions. I always think of them as US and Japan, but I don't know the actual origins.

I'm pretty sure the majority of parts made today don't put the Base in the middle, where I "expect" it.

Parts with significant power rating often have one fat leg to carry the chip. It may only be fat inside the plastic, not the leg you see. In most semiconductor processes this will be the most positive voltage (NPN collector), but in a PNP process it may be the most negative pin (PNP collector).

Find a better data-sheet. Yes, the layout software may know something, but don't trust it.

> the npn and pnp are runnign ....with bases and collectors tied together...

I forgot your strange scheme. I'll give you a tidbit: you probably will not be able to tell, in that circuit, if you switch the Emitter and Collector. That is unusual; it is usually critical to get them right. Here it would make about a 1% difference in gain, in parts that vary 50% from one to the next.

apparently, i had grabbed the link for the mouser catalog page; the actual manuf. data sheet showed all three...lol.

on a generic Google search, my transistors turned up a couple times in peoples posts on other forums about other projects...one in particular caught my eye. Under the parts list, both my transistors were used, with a "NOTE:" attached to the parts list data, stating to be careful as the "pinouts are reversed from normal", LMAO. SO, its not just ME, hee hee (though, usually it is just me, ha)

I'm re-doing the PCB layout again. I've "bummed" the layout, IE, got a better layout that conserves space more.` Plus, the traces are less haphazard looking, and I now have fewer "back side" traces; i want to keep as many on the front as possible.

Question: would this circuit lend itself well to a breadboard test setup? I used breadboard a lot when i was doing digital; hi freq analog doesnt respond well to breadboard and hookup wire, i seem to remember. My old breadboard piece, assuming I could even LOCATE it now, lmao, was tiring anyways, had a few loose connection holes and such, using it was like driving an old bomb of a car...you had to "know" where those connections were loose and avoid them...if this circuit would lend itself well to breadboarding for testing, it would make a suitable excuse to get a bigger chunk of breadboard proto, my old one was smallish anyways.

PS - you guys spoil me; lol...i cut out of my PCB software to post a question...i pop back a half hour later, not really expecting a response yet, just taking a break and looking for new posts, and BAM, theres an answer...this place is like the ultimate "tech support" line, and everybody speaks english, LMAO..."No comprendar el resistoro, senor...cuantas las voltas, eh?" LMAO...