This MOSFET power audio amplifier circuit is designed using an TL071C operational amplifier some electronic components and two power MOSFET transistors .
Maximumoutput power that can be delivered by this MOSFET power audio amplifier circuit it's up to 45W on a load of 8 ohms.
T5 and T6 FET's are driven by potential differences on the R8 and R13. Since the supply voltage required is well above the normal for an common operational amplifier, transistors T1 and T2 were in series on supply lines of the integrated circuit. These transistors are provided on a fixed potential of ± 15 V Zener diodes D1 and D2 through. Thus, the voltage of the operational amplifier will always be 14.4 V.
Current setting is done through the rest of T3 and T4. It is very important for T4 and T5 to be thermally coupled so that the current stability is assured rest. Total current absorbed by the amplifier is adjusted to about 75 mA, with the potentiometer P1 (in this case, the current through the FET's will be about 70 mA).
MOSFET transistors must be mounted on a heat radiator at least 1K / W.
With a stable power supply of ± 30 V, 45 W amplifier can provide on a load of 8 ohms or 70 watts on a 4 ohm load.