In our time there are many players of different companies. They all eat from batteries such as "Tom thumb". These batteries have a small capacity and the operation of the player quickly "sit." Therefore it is better in stationary conditions players feed from the mains via the power supply, as the price of batteries in our time "bite".
In the electronic literature there are descriptions of different power supplies for electronic devices, including for players with a 3-volt power supply. As described below, the unit provides an output voltage of 3 V At a load current up to 400 mA, which is sufficient to power any player or radio. For this power supply uses a transformer and chassis from the power supply calculator type MK-62 (electronics D2-10m). The transformer leave primary (AC) winding and the secondary winding her. Now it contains 270 turns of wire PEL or sew 0,23.
Another feature of this power supply. As the output transistor used Japanese transistor D837B. All of our transistors are not provide the desired stabilization of the output voltage at 3 In the change current consumption from 50-70 mA (radio mode) to 35-400 mA (mode the tape recorder). The rest of the scheme of the voltage regulator classic compensation type.
The output transistor needs to be put on a small heatsink. Mounting block power is made in hinged manner.
Author: O. G. Rashitov, Kiev