30W MosFet Audio Amplifier IRF530-IRF9530
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Description:
This project was a sort of challenge: designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality.
The Power Amplifier section employs only three transistors and a handful of resistors and capacitors in a shunt feedback configuration but can deliver more than 18W into 8 Ohm with <0.08% THD @ 1KHz at the onset of clipping (0.04% @ 1W - 1KHz and 0.02% @ 1W - 10KHz) and up to 30W into a 4 Ohm load.
To obtain such a performance and to ensure overall stability of this very simple circuitry, a suitable regulated dc power supply is mandatory. This is not a snag because it also helps in keeping noise and hum of the preamp to very low levels and guarantees a predictable output power into different load impedances. Finally, as the amplifier requires only a single rail supply, a very good dc voltage regulator capable of supplying more than 2 Amps @ 40V can be implemented with a few parts also.
Power Amplifier Parts:
| R1 |
2K2 1/4W Resistor |
R2
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27K 1/4W Resistor |
R3,R4
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2K2 1/2W Trimmers Cermet or Carbon (or 2K) |
R5
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100R 1/4W Resistor |
R6
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1K 1/4W Resistor |
R7,R8
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330R 1/4W Resistors |
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C1
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22µF 25V Electrolytic Capacitor |
C2
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47pF 63V Polystyrene or Ceramic Capacitor |
C3,C4
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100µF 50V Electrolytic Capacitors |
C5
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2200µF 50V Electrolytic Capacitor |
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Q1
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BC550C 45V 100mA Low noise High gain NPN Transistor |
Q2
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IRF530 100V 14A N-Channel Hexfet Transistor (or MTP12N10) |
Q3
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IRF9530 100V 12A P-Channel Hexfet Transistor (or MTP12P10) |
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