Here the schematic diagram of headphone amplifier which built based single MOSFET as the main amplification component. This circuit is quite simple and easy to built with minimum cost.
Circuit notes:
- The MOSFET type is IRF610.
- The above diagram design is for one channel only, just build the same circuit in one PCB to make it stereo channel.
- All resistor wattage is 0.25W except the resistor around LM317 which is 0.5W
- Connect signal ground to the power supply ground. If there is a hum, try connecting with a resistor parallel with capacitor.
- Use regulated power supply 10-12VDC
The amplifier concept is simple and follows a typical single-ended class A circuit utilizing an active constant current source (CCS) in place of a passive resistor. A CCS doubles the efficiency of the circuit over that where a passive load resistor is used, bringing it to a maximum of 25%.
