Amplifier CLASS A

06/05/2026

Transistor Power Amplifier

26/04/2026

Soft Start Circuit Protect Amplifier

This is a soft start circuit diagram for an amplifier. Every amplifier needs this circuit board. A soft start circuit.

26/04/2026

Mosfet 100W
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100watt MOSFET Amplifier Circuit

This is a circuit diagram for a 100-watt MOSFET Audio Power Amplifier. It is a classic Class AB design that utilizes a complementary pair of MOSFETs in the output stage to drive a speaker.

Input Stage: Uses a differential pair (Q1, Q18) to compare the input signal with the feedback signal, ensuring low distortion and stable gain.

Voltage Amplification Stage (VAS): Q2 and Q3 amplify the signal's voltage level to a point where it can drive the output stage.

Bias Control: Q4 (BD139) acts as a Vbe multiplier. It is typically mounted on the same heatsink as the power MOSFETs to provide thermal compensation, preventing thermal runaway by adjusting the bias current as temperatures rise.

Driver Stage: Q5 and Q6 (BD139/BD140) serve as buffers to provide the necessary current to charge and discharge the gate capacitance of the power MOSFETs.

Output Stage: Features the IRF240 (N-channel) and IRF9240 (P-channel) MOSFETs. These are high-power devices capable of delivering 100 watts into a typical 8-ohm speaker load.

Frequency Response: Generally 20Hz to 20kHz for high-fidelity audio.
Protection: D8 and D9 (12V Zener diodes) protect the MOSFET gates from excessive voltage.

[!WARNING]
Building and testing high-power amplifiers involves high DC voltages +-50V Ensure all capacitors are properly rated (at least 63V) and use a large heatsink for the output MOSFETs. Incorrect assembly can lead to component failure or fire hazards. Always use a current-limited power supply or a "dim bulb tester" for the initial power-up.

18/04/2026

https://drive.google.com/drive/mobile/folders/1OWTjHjvDtSLsSaOiG_HQSvaZLnta5YPE?fbclid=IwVERTSARQDsdleHRuA2FlbQIxMABzcnRjBmFwcF9pZAwzNTA2ODU1MzE3MjgAAR7d5PO0Co-f56lH8hZjEYwZIhVg9-lJlDpOWRXswJDK19BWZpp7fx8l-n1pKQ_aem_wfpieYLV3-8_MkfSADvtKA

18/04/2026

JLH1969 with PCB Download

83 likes, 21 comments. "JLH1969 Class A Amplifier In Selfmade PCB"

12/04/2026

TIP Transistor

09/04/2026

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Clasik amp