Driving an 8 ohm speaker with common collector circuit

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createdtowatch worldcup

Joined Oct 4, 2018
11
Hello everyone, I have not yet put values in my circuit. The first 2 stages should provide a total voltage gain of 75. Will this circuit layout able to drive the 8 ohm speaker ?(I forgot to add two voltage divider resistors before the darlington)
2018-10-05_163129.png
 

danadak

Joined Mar 10, 2018
3,605
Do you need to do this discrete ? There are so many
low cost audio amp ICs that have all the protections
and low distrortion, and easy to use. Class D versions
getyou h igh efficiency as well

Regards, Dana.
 

Thread Starter

createdtowatch worldcup

Joined Oct 4, 2018
11
Do you need to do this discrete ? There are so many
low cost audio amp ICs that have all the protections
and low distrortion, and easy to use. Class D versions
getyou h igh efficiency as well

Regards, Dana.
I was given to use only BJT npn , no I need to design from the most basic elements
 

AnalogKid

Joined Aug 1, 2013
8,132
Will this circuit layout able to drive the 8 ohm speaker ?
Yes, but not very well. The darlington can source lots of current into the speaker, but the only path to sink current out of the speaker is through the darlington's emitter resistor. This means the amplifier's output impedance is not symmetrical. The smaller the resistor, the better the audio, but also the more heat the circuit will dissipate. A class A amplifier is very inefficient. It is common for a circuit like this to dissipate 2 watts in heat for every 1 watt that goes into the speaker.

ak
 
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