The transistors of this amplifier for 8-200 headphones may be the BC548 or equivalent to replace the original that no longer exists. Power supply can be done with voltages between 6 to 9 V and the consumption is low. The circuit also serves as a stage for experimental audio intercom or radio. For a 9 V voltage supply can be used to output the BD135. The input impedance is high and power supply is used, it must have excellent filtration. The output power is d tens of milliwatts only.
