The portable headphone amplifier circuit is very easy to build because it uses only 3 transistors. The portable headphone amplifier can be directly connected to the CD player, or tape recorder.
The headphone amplifier circuit works well on headphones with impedance 32, 100, 300, 600 and 2000 ohm. Because the headphones have two speakers for stereo channels, it is recommended to make two series of the same.
If this circuit is built for stereo channel, then B1, SW1, J1 and C3 also be done with the stereo. R3 resistor value listed on the headphone amplifier circuit to the impedance of 300 ohms. If you are going to use headphones with an impedance of 600 ohms, then replace the value of R3 to 100k.
Portable Headphone Amplifier Circuit Technical Data:
- Current drain: 35mA per channel with 32 Ohms impedance headphones. Much less with higher impedance loads
- Output voltage: Above 2V peak-to-peak on all loads
- Sensitivity: 90mV RMS input for 2V peak-to-peak output
- Frequency response: Flat from 30Hz to 20KHz
- Total harmonic distortion @ 1KHz & 10KHz: Below 0.05% on 32 to 600 Ohms load and up to 1.5V peak-to-peak output. Below 0.1% at maximum output
Unconditionally stable on capacitive loads.