It can't be considered anything - it's not a working circuit. It looks like someone who didn't know anything about electronics saw a circuit once, and then tried to draw it from memory a week later. Where did it come from?.
Q7-Q8 is a darlington pair connected to the collector of Q3. In the case that Q3 conducts anything, Q7-Q8 slams the output drivers against the Vcc rail producing a square wave. If C3 is the right value then Q2 will try to cut off the base current to Q3 and it will be an oscillator but its stability depends on R7. If Q4 is the right geometry then it will provide some compensation to Q2. But Q5 and Q6 are a current sink and maximize the voltage gain of Q7 and Q8 so they provide the best possible square waves.
I copied and pasted some comments about these weird circuits in this theread:
"It's not a real design, various bits are missing and many of the values are completely wrong.
It needs throwing away and starting from scratch.
A recipe for disaster. It's more likely to cause a chain reaction self destruct.
Looks rubbish to me?
It is the strangest amplifier that I have ever seen.
Where did you find this one?
Like your previous circuit, it doesn't look like a complete working design, and this one even less so.
It's still non-functional, nothing like a working amplifier.
It looks like someone who didn't know anything about electronics saw a circuit once, and then tried to draw it from memory a week later."
I'm young and inexperienced..........I'm just trying to understand power amplifier ccts and get views...........i don't know what I post works or not....and that's why i welcome any views....
I'm young and inexperienced..........I'm just trying to understand power amplifier ccts and get views...........i don't know what I post works or not....and that's why i welcome any views....
In your last circuit, there was a voltage reference made form Z1 & Q1, which might be the only functional part of the design. But it has no compensation for temperature.
Yeah thanks Audioguru, Im going to try downloading that document again now. My net did not download it when i tried yesterday....it was taking forever.....
What do R6 and C1 do?
I tried twice to download it...it gave me the same error msg:
Foxit Reader: Format error: not a PDF or corrupted.....
I downloaded it last night (as it wasn't on my new computer), it worked absolutely fine - I suggest trying it again - do you have a slow connection speed?, and lot's of breaks in service?.