100W Basic MOSFET Amplifier Circuit

This 100W Basic MOSFET Amplifier Circuit has a simple construction and can be built at relatively low cost. This amplifier circuit can be used as universal HiFi amplifier and guitar amplifiers, etc.

This 100W Basic MOSFET Amplifier Circuit can produce 100 Watts rms of power at 8ohm loudspeaker load and 160 watts rms at 4 ohm load. With 100 Watt power, the level of amplifier distortion produced is very small, which is only 0.1%.

100W Basic MOSFET Amplifier Circuit Diagram and PCB Layout

100w basic mosfet amplifier circuit

PCB Layout

basic mosfet amplifier circuit pcbThe first amplify consists of transistors T1 and T2 are constructed as a differential amplifier, which is the source of current is adjustable with a resistor R3. Potentiometer P1 serves to adjust the DC voltage amplifier output. The P1 will be set DC voltage at the amplifier output should be close to 0V.

This mosfet amplifier circuit has an input sensitivity of 1.2 volts, and the gain is determined by R6 / R7, which is 27x the results obtained. Transistors T5 and T6 will make a second differential amplifier. This will provide optimum power of the level of the differential amplifier.

This amplifier circuit has several advantages, one of which is a very good level of linearity. MOSFET Transistor final level work in class AB. Potentiometer P2 must be setup so that when quiescent reached 50 mA to 100 mA.

The Method to set potensiomater P2 is by turning P2 at minimum position. Furthermore mV-DC multimeter placed between R14 and R15. Then turn P2 a little bit until the voltmeter reading +/- 16.5 mV.

Fuse F1 and F2 will protect the mosfet amplifier from short circuit. The power supply is needed in this amplifier circuit is between 45 VDC to 55VDC with symmetric system. So that the mosfet amplifier circuit has high accuracy, I will recommend using all resistors with 1% tolerance metalfilm 1/4 Watt.

To avoid things that are not desirable, before connecting the speakers to the amplifier, connect a voltmeter in advance to see the DC output voltage. This voltage should not be more than 50mV. If more than 50VDC, don’t connect speakers to the amplifier and check for errors in the mosfet amplifier circuit.

100W Basic MOSFET Amplifier Circuit Parts list :

C1 = 2.2 uF MKP, MKT 100 V
C2 = 330 pF ceramic 50 V
C3 = 100 nF MKP, MKT 100 V
C4 = 40 uF 100 V electro-chemical
C5, C6 = 18 pF ceramic 50 V
C7 = 100 nF MKP, MKT 250 V
C8 = 47 uF 100 V)
R1 = 47 K
R 3 = 470 Ohms
R2 = 2K2
R4, R5 = 3K9
R6 = 1 K
R7 = 27 K
R8, R9, R11 = 100 ohms
R10 = 10 K
R12, R13 = 470 ohms
R14, R15 = 0.33 ohm 5 watts
R16 = 10 ohm 3 watt
R17 = 1 K
R18, R19 = 10K
T1, T2, T9, T10 = 2N5401, ZTX558, BC556B (note the different pinout – take care for pin layout)
T3, T4 = BF470, MJE350, 2SB649
T5, T6 = BF469, MJE340, 2SD669
T7 = IRFP240, 2SK1530, 2SJ162, BUZ900DP, BUZ901DP (note the different pinout – take care for pin layout: GDS GSD)
T8 = IRFP9240, 2SJ201, 2SK1058, BUZ905DP, BUZ906DP (note the different pinout – take care for pin layout: GDS GSD)
P1 = 100 ohms (25 laps – 25 turns)
P2 = 2K5 (25 laps – 25 turns)
F1, F2 = 3 T A