25 Watt MosFet Audio Amplifier

[b:acbecb2875]High Quality simple unit
No need for a preamplifier[/b:acbecb2875]

* Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need.
* Q6 & Q7 must have a small U-shaped heatsink.
* Q8 & Q9 must be mounted on heatsink.
* Adjust R11 to set quiescent current at 100mA (best measured with an Avo-meter connected in series to Q8 Drain) with no input signal.
* A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 to output ground. Then connect separately the input and output grounds to power supply ground.

[b:acbecb2875]Technical data:[/b:acbecb2875]
* Output power: well in excess of 25 Watt RMS @ 8 Ohm (1KHz sine wave)
* Sensitivity: 200mV input for 25W output
* Frequency response: 30Hz to 20KHz -1dB
* Total harmonic distortion @ 1KHz: 0.1W 0.014% 1W 0.006% 10W 0.006% 20W 0.007% 25W 0.01%
* Total harmonic distortion @10KHz: 0.1W 0.024% 1W 0.016% 10W 0.02% 20W 0.045% 25W 0.07%
* Unconditionally stable on capacitive loads

For the power supply see: PS25.gif

Source: [url]http://www.redcircuits.com/Page2.htm[/url]

Copyright Flavio Dellepiane

A kit is available, mail to: [email protected] with subject [i:acbecb2875]25 Watt MosFet Audio Amplifier Kit[/i:acbecb2875]Parts:2 x 47K 1/4W Resistors (R1,R4)
1 x 4K7 1/4W Resistor (R2)
1 x 1K5 1/4W Resistor (R3)
1 x 390R 1/4W Resistor (R5)
1 x 470R 1/4W Resistor (R6)
1 x 33K 1/4W Resistor (R7)
1 x 150K 1/4W Resistor (R8)
1 x 15K 1/4W Resistor (R9)
1 x 27R 1/4W Resistor (R10)
1 x 500R 1/2W Trimmer Cermet (R11)
3 x 10R 1/4W Resistors (R12,R13,R16)
2 x 220R 1/4W Resistors (R14,R15)
1 x 8R2 2W Resistor (R17)
1 x R22 4W Resistor (wirewound) (R18)

1 x 470nF 63V Polyester Capacitor (C1)
1 x 330pF 63V Polystyrene Capacitor (C2)
2 x 470µF 63V Electrolytic Capacitors (C3, C5)
4 x 100nF 63V Polyester Capacitors (C4,C6,C8,C11)
1 x 100µF 25V Electrolytic Capacitor (C7)
1 x 10pF 63V Polystyrene Capacitor (C9)
1 x 1µF 63V Polyester Capacitor (C10)

5 x BC560C 45V 100mA Low noise High gain PNP Transistors (Q1-Q5)
1 x BD140 80V 1.5A PNP Transistor (Q6)
1 x BD139 80V 1.5A NPN Transistor (Q7)
1 x IRF530 100V 14A N-Channel Hexfet Transistor (Q8)
1 x IRF9530 100V 12A P-Channel Hexfet Transistor (Q9)

Power supply:

1 x 3K3 1/2W Resistor (R1)
1 x 10nF 1000V Polyester Capacitor (C1)
2 x 4700µF 50V Electrolytic Capacitors (C2, C3)
2 x 100nF 63V Polyester Capacitors (C4, C5)
1 x 200V 8A Diode bridge (D1)
1 x 5mm. Red LED (D2)
2 x 3.15A Fuses with sockets (F1, F2)
1 x 220V Primary, 25 + 25V Secondary 120VA Mains transformer (T1)
1 x Male Mains plug (PL1)
1 x SPST Mains switch (SW1)

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