Vermes
Advanced Member level 4
This stereo amplifier was based on transistors 2N3055. Non-symmetrical power supply supplies the device with approximately 55VDC, what is then filtered by 10000uF/100V capacitor. Signal goes from input switch to the power amplifier. It was built on multiplexer 4052 with symmetrical supply and controlled from counter 4017 with shortened counting cycle to three. After selection of the correct source, the signal goes to the potentiometer and then to the power level. After gain, the signal goes to headphone socket and directly to speaker sockets. Headphone socket disconnects the sound of speakers after connecting the headphones.
Two transformers supply the amplifier. Main transformer has a power of about 120VA. Another (auxiliary) is about 2VA and supplies the system of switch implemented by another 4017 in configuration of counting two. It controls the relay that cuts off the mains voltage of the main transformer. Main mechanical mains switch is placed in the rear of the amplifier.
Housing is a classic KM with front and rear walls made of aluminum.
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Link to original thread - Jak zagospodarować domowe szpargały... czyli wzmacniacz stereo.