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Simple Headphone Amplifier by BC549C
This headphone amplifier provides a gain of less than 10 by a single stage common emitter amplifier and then via a direct coupled emitter follower configuration per each channel. As it seen from the diagram two identical circuitry is drawn for left and right which are mainly based on BC549C transistors.
You should use dual type logarithmic pots to adjust two channel vollumes at the same time. One another 47 kΩ pot is also provided to balance the outputs. You should turn it till you get the same volume levels from each channel. If the balance pot turns to one side, then the other side will be shorted to ground.
The load should be 8 Ohm but higherimpedance loads will also work well.
At the output, 2.2 kΩ resistors are connected to the capacitors and to the ground to remove the DC potential from this coupling capacitors and prevent any “thump” being heard when headphones are plugged in.
The supply voltage range is from 6V to 20V.