Electronic schematic question. Distinction of transistors.

SIGforum

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/320601935/m/6140008154

January 06, 2019, 11:11 AM

mark123

Electronic schematic question. Distinction of transistors.

This is something I've not come across and i don't remember there being a schematic distinction between transistors. They are both NPN but one shows the base as a line and the other as a rectangle. Why the distinction?

January 06, 2019, 11:26 AM

Pipe Smoker

AFAIK, that isn’t standard notation. Maybe Q5 is a power transistor whereas Q1 is a small signal transistor.

January 06, 2019, 11:27 AM

Sig Vicious

My guess is a BJT.

https://www.electronics-notes....nsistors-bipolar.php

January 06, 2019, 11:53 AM

mark123

quote:
Originally posted by Sig Vicious:
My guess is a BJT.

https://www.electronics-notes....nsistors-bipolar.php

All NPNs and PNPs are bipolar junction transistors.

January 06, 2019, 11:54 AM

mark123

quote:
Originally posted by Pipe Smoker:
AFAIK, that isn’t standard notation. Maybe Q5 is a power transistor whereas Q1 is a small signal transistor.

That seems plausible. I'll have to check the rest of the circuit to see if that's the case.

January 06, 2019, 01:10 PM

4MUL8R

AARL may have instructional material for ham radio operators online, where these distinctions are described.

January 06, 2019, 01:22 PM

radioman

can you share the rest of the circuit? that could give some hints.

maybe an IGBJT? Just guessing.

January 06, 2019, 01:50 PM

mark123

quote:
Originally posted by radioman:
can you share the rest of the circuit? that could give some hints.

maybe and IGBJT? Just guessimg.

It's the schematic for what's inside an LMx08:
http://www.mit.edu/~6.301/LM108.pdf

January 06, 2019, 02:42 PM

Pipe Smoker

When I first looked at this schematic (half way down the page), it appeared that all NPNs had the rectangular base, and all PNPs had the thin base. But then I noticed Q1, Q2, and Q4. Dang, that theory is shot.

http://www.righto.com/2016/12/...p-superbeta.html?m=1

But if Q13 is a power transistor, then Q14 ought to be a power transistor too, so just don’t know…

January 06, 2019, 02:58 PM

mark123

I wonder if it is just something as simple as two people worked on the drawing using their own style.

January 06, 2019, 05:46 PM

sig operator

Looks like one draftsman. Difference may be the construction details within the op amp on the chip substrate. Hard to tell.

January 06, 2019, 08:58 PM

braillediver

? This link might indicate P\N Channel MOSFETS?

https://cdn.sparkfun.com/asset...ce395f7558000002.png

Definitely looks like a purposeful difference.

____________________________________________________

The butcher with the sharpest knife has the warmest heart.

January 06, 2019, 11:44 PM

radioman

The answer my friend is in this book, on printed page 50, location 75 in this scan:

https://archive.org/details/Na...andbook1994/page/n75

note the lower gain (beta) transistors have the wider base rectangle. These also have a higher breakdown voltage.

January 06, 2019, 11:49 PM

bushpilot

Dang Radioman, You are good buddy. That answer is a real Elmer for sure.

Thanks.
W5SCM

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January 07, 2019, 03:05 AM

mark123

Excellent work, my good man. I owe you an instakarma.