Wow! While I am a firm believer in KISS, I do get off on all this engineering stuff. I'll start with a big thanks to both of you guys for the ideas.
First - Spec - A 2N2222 would work better?
I was just going to grab a 2N3904, my normal go-to transistor, but the 2N2222 drawer is right next to that, so it's worth a try. I might even try them both to see the difference.
I planned to use the op amp because I have an extra op amp in the package of 4, and it could be a long way to a 10-bit A/D input, so I thought buffering it could reduce potential noise pickup, but no it's not really necessary.
I suppose it is a good idea use your circuit to take advantage of some gain in the transistor if it's there. That could double the resolution to about 1/3 degree.
Really though, I'm offended at the capacitor addition!
Seriously, my supply will be well bypassed as always. And I would
never lie about bypass caps. I'm just tired of drawing them in everywhere.
But of course if I were to add just one more resistor, I could instead take advantage of the op-amps gain like MikeMI's circuit. After all it's just sitting there drawing power anyways. Possibly 1/22th of a degree resolution? I'm tempted...
OK, after thinking about it, it's not worth the effort to design in a lot of resolution. But if it's essentially there already...why not use it?
I'll play around with spec's Y circuit and see what kind of performance I can get with different transistors, even though I'll have to purchase yet another resistor! If it gives me any trouble then I may just add some op-amp gain with MikeMI's Z circuit - assuming I can buy another resistor on an installment plan...1 cent now and 1 cent due in 30 days
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One unique feature though about a string of transistors: Instead of detecting the temperature at one specific point (which is normally done), a string of transistors spaced apart will measure more of an average of the surrounding air temperature.
BTW: this is going into a rocket launcher. It's to be battery powered but they'll be plenty of "amp-acity" there. +5V will be double-regulated and heavily filtered. There will be a display showing various voltages, angles, counts etc. so what the heck-why not display temperature also? It would only be needed for human curiosity, it does not factor into the rocket launching circuitry.
p.s. sorry for all the faces, I just discovered all the selections.