MOSFET audio amplifier circuit (10 watt)

The diagram shown here is of a 10W MOSFET audio amplifier circuit that requires only a single supply. Single rail supply is seldom used in Class-B power amplifiers. Anyway, for low power applications like this it’s quite fine. Actually I got this circuit from an old cassette player that is still working and I am publishing it as it is. The powers MOSFETs BD512 and BD522 are obsolete now and so you may use any other matching power MOSFETS instead of them.
Transistors Q1 and Q2 is wired as a Darlington pair works as the preamplifier. Preset R3 controls the quiescent current while R2 provides feedback. Output is coupled to speaker through capacitor C4. Capacitor C5 is the power supply filter and C2 is the input DC decoupling capacitor.

• The circuit can be assembled on a vero board.
• Use 30V DC for powering the circuit.
• Do not expect much performance from this amplifier.
• Capacitors C3, C4, C5 must be rated 50V and C2 can be 10V.
• Use a 8 ohm 15W speaker as load.

S:circuitstoday.com