AX-M140 Amplifier Audio Output Circuit Board

Here are some photographs showing the AX-M140 audio power output circuit board. I did not encounter any problems with this and it seems like a very design.

An interesting feature of the TDA7294 power amplifier is the lack of external overload protection circuitry. This is because it has built in protection, including thermal overload protection. Hence, there is no requirement for a protection relay to disconnect the speakers. In conventional amplifier design, an additional relay usually controls the power rails of the audio output stage, and a standby circuit and processor usually controls this relay. However, in this amplifier design, the toroidal transformer remains powered all the time, because the IC has built-in standby circuitry activated with a control signal fed at pin 9. This is probably one of the best ICs I have come across as it reduces the component count drastically; hence, it may be an ideal candidate for hobbyists to use as it simplifies the circuit design and component count.

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