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Please help me to understand the transistor circuit

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eepty

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Attached a transistor circuit here. I do not understand why the base and emitter of the NPN is connected together, and what is it use for?

npn.PNG

Thank you.
 

Q1 indeed looks useless for me.
Sure this is a PNP? Where did you get this circuit?
 

Q1 acts as a diode with the collector being the cathode.

Otherwise the circuit operation makes little sense to me. :???:
 

I have done this (transistor as diode, B=E) many times in IC
designs where I just wanted a plain old dumb 40V diode but
had a CAD group who just could not be bothered to add one
to the "blessed" library, and a modeling group who likewise
gave zero fvcks about making a decent model. So you get
to use what's on your plate. We would call this a "C-B
transdiode" (transistor (mis)applied as diode).

But the larger picture is still a mystery, it looks like the
PNP is used upside down as well and there's nothing to
indicate actual (let alone desired) function. Offhand it
looks like a waste of three components.
 

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