Although it is an old design, it is a very high quality and powerful amplifier circuit with MOSFETs. The working voltage of the circuit is symmetrical. Two MOSFETs are used in the +-40 volt DC output. IRF240 and IRF9240. The PCB design of the hi-fi amplifier circuit is very nice in layout, and a relay delay circuit has also been added to protect the speaker.
When there is no signal at the amplifier input, the P2 trimpot will be adjusted to 20mv on the R1 resistor.
Source: www.vnav.vn
Symmetric Power Supply circuit 10A LM337 LM317 Adjustable Voltage
Symmetric Power Supply circuit per channel 5 amps powering a total of 10 amps voltage control LM317 (negative – at the LM337) is done with LM317 1 amp works fine but the output BD911 BD912 transistors with a strengthened 5 amps made to give filter capacitor, diode bridge and the main circuit all in one pcb on 5Amp Voltage Adjustable Symmetrical Power Supply circuit
This is a modified Version of Elektor Elektronics Mag Amplifier but with many errors in PCB mostly transistors replaced with Japanese transistors witch have different Pin configurations but PCB is not changed.Non Practical Project(I think)