In normal stereo amplifier is 2 speakers. And if a mono amplifier is a single speaker.
But this circuit is a special Mono amplifier. It can drive 2 speakers at the same time.
Without parallel or serial access. Because It causes the impedance of the speaker changes.
But in this circuit, we continue the speakers instead of the collector resistor (RC) of the transistor.
So, It can amplify out of 2 speakers.
How it works
First, enter the power supply to the circuit and the audio signal to the input terminal. Then, the audio signal coupling to through the C1 and R1 to amplifies by transistor-Q1.
Which the Q1 is a first Preamplifier to increase a little signal up. Before sending it to Q2.
Next, the Q2 is connected to the emitter follower circuit. Its function is a driver amplifier to boost up a signal from the preamplifier section. To more power to drive the Q3 runs well.
And Q3 is a power amplifier out of the speaker.
It has the feedback of an audio signal through the VR1 and R2 to the pin B of Q2. To control the stability of working for good.
This circuit is an output of 40 milliwatts of distortion of the signal rate is at 0.1 percent. And frequency response from 15 Hz – 200 kHz.
The power supply voltage of 9V to 20V.
You are looking for Mono amplifier. You have many choices. For example:
Parts you will need
0.25W 5% resistors
R4: 10 ohms
VR1: 50K Potentiometer
C1: 0.22uF 50V Ceramic
C2: 5pF 50V Ceramic
C3, C4: 10pF 50V Ceramic
C5: 1000uF 16V Electrolytic
Q1: BC558, 45V 0.1A PNP transistor
Q2: BD140,80V 1.5A PNP Transistor
Q3: TIP2955, 60V, 15A PNP transistor
Note: I have published this circuit for a long time. But I haven’t tried it. Found many mistakes. I found this website, put this content into the website. And change the transistor number. This is a good idea. Thanks.
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