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Transistor amplifier circuit

somenewb

Dec 3, 2022
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Dec 3, 2022
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Hello,

I am having trouble understanding how the attached circuit works. It is supposed to a kind of amplifier circuit that also compensates for temperature changes, but I have no clue how it works. It would be highly appreciated if someone could explain it. Thank you.

1670080229236.png
 

Alec_t

Jul 7, 2015
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Welcome to maker.pro!
The circuit won't work, because Q3 is upside down.
Once that's corrected, plug in some component values and let LTspice show you how the circuit behaves.
BTW, it always helps if you post your .asc file. The forum can accept that format as an upload.
 

somenewb

Dec 3, 2022
2
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Dec 3, 2022
Messages
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Welcome to maker.pro!
The circuit won't work, because Q3 is upside down.
Once that's corrected, plug in some component values and let LTspice show you how the circuit behaves.
BTW, it always helps if you post your .asc file. The forum can accept that format as an upload.
Thank you for your answer. Could you please explain why it won't work? What do you mean by Q3 being upside-down? It is pnp transistor, isn't it?
Also, I am not quite sure how to test this circuit in LTspice. Should I apply a sine wave and the base of Q3 transistor (before the voltage divider) and sample the output right after R6?
 

AnalogKid

Jun 10, 2015
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Jun 10, 2015
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"Upside-down" means that the Q3 emitter and collector are reversed. But another possible problem is that Q3 is connected correctly, but is supposed to be an NPN type. Rather than keeping us in suspense, please give us more information.

Where did the circuit come from? Can you post a link to the source?

What is it you are trying to achieve? If you want an amplifier, then what is the input and where is it connected? Also, what is the output you require, and where is the load or downstream circuit connected?

If you click on a net, you can add a name. This will make this discussion much easier.

ak
 

crutschow

May 7, 2021
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May 7, 2021
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What do you mean by Q3 being upside-down? It is pnp transistor, isn't it?
Yes it is.
And what collector-emitter voltage polarity is required for a PNP transistor to operate properly?
The answer to that will show why it is upside down in your circuit.
 

danadak

Feb 19, 2021
768
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Feb 19, 2021
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768
Actually you can reverse connect emitter and collector on transistors and get
different results. For example on many this will allow one to achieve lower
Vcesat on some devices, when operated as a switch.

So we are al trying to look at this as a Darlington, but I would ask is there
another explanation for this connection ? Got me but I am suspicious.

I simmed this, it works, but no G in the circuit. Which is not explaining much.
Could there be Zin and / or BW effects that circuit advances ?

Just asking because I do not have a clue.


Regards, Dana.
 

dragon

Oct 31, 2022
248
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Oct 31, 2022
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248
Looks like you should untie the base from the power and connect it to the music signal, then it should go, i dont know how well tho, could be pretty average. but maybe not, might work really good due to the pair of transistors, ive never tried it personally.
 
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