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Need help in understanding the circuit

ElectroNewbie98

New Member
Hello, can you help me to understand this circuit? I think it works as power amplifier but I'm kinda new in electronics, so any help is appreciated. Also I'm interested in calculations of this circuit, how much power does it increase in different stages of the circuit or how do I calculate that? Sorry if my english is broken :)circuit.png
 

audioguru

Well-Known Member
Most Helpful Member
I straightened a few wires.
The first transistor has no base biasing.
The entire circuit will do nothing because it has no power supply voltage.
 

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Pommie

Well-Known Member
Most Helpful Member
Should the 5V be at the bottom of C13? Plus, you have lots of caps marked 4.7. - 4.7 what? Farads?

It's very unusual to have ground symbols pointing up!

Mike.
 

wkrug

Active Member
IMHO that thing won't work proper.
There is only one biased Transistor?!
And that's direct coupled to a an collector Circuit stage without biasing?!
The last Power Transistor is DC wise shorted with a Coil.

The Circuit C4 / L4 looks like a Bandlock between 2 Amp Stages?!

At RF some things work a little different, but I think that will not work!

I'll suggest You to look for a better Schematic.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
IMHO that thing won't work proper.
There is only one biased Transistor?!
Not at all - it's obviously NOT a functional circuit - but the only non-biased one is the first one. The higher powered stages are biased in class-C as is normal for a transmitter.

However, I suspect transmitters isn't something the OP should be getting involved in, as it's not really something for absolute beginners (I'm presuming he's drawn the circuit himself?, based on the non-functioning examples from text books?).
 

unclejed613

Well-Known Member
Most Helpful Member
with class C, he's gonna need a whole lot more filtering at the output....
 

Nigel Goodwin

Super Moderator
Most Helpful Member
with class C, he's gonna need a whole lot more filtering at the output....
I suspect you probably don't understand how class C transmitters work?.

You don't need a 'huge' amount of filtering, as the tuning (L10/C18) removed most harmonics, and if then followed by extra filtering as well.

Basically the transistor is a switch, causing the tuned circuit to 'ring' creating a sine wave.
 

unclejed613

Well-Known Member
Most Helpful Member
I suspect you probably don't understand how class C transmitters work?.
as a matter of fact i do... what he has shown there isn't enough for modern harmonic suppression standards
 

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