SW radio using OP amplifier

[Audioguru]

The LM386 is fairly old and is a single mono amplifier. With a 5V supply its output is inly 0.14W with low distortion into 8 ohms or 0.2W into 4 ohms. It costs $1.02US today. it wastes battery power making heat.

A modern PAM8403 is a stereo amplifier IC. With a 5V supply each channel produces 1.4W with low distortion into 8 ohms or 2.5W into 4 ohms. It costs $80US today. It stays cool and is very efficient.

 

[Harald Kapp]

It costs $80US today.

That sure should be 0.80 $?

 

[Audioguru]

That sure should be 0.80 $?

I think I wrote $0.80US but my keyboard has its own mind

Then a much more powerful modern amplifier with 2 channels costs less than the old single channel low power amplifier.

 

[aurelZ]

The PAM8403 is a 3W, class-D audio amplifier.
... so as such cannot be used as receiver,here is not how much cost than how to build....

 

[Harald Kapp]

so as such cannot be used as receiver

It is not meant to be one. It is meant to amplify the signal from a proper receiver.

 

[Audioguru]

He talked about using an old Mickey Mouse "regenerative" detector but did not show it

Using his very old 741 opamp as a power amplifier to drive an 8 ohm speaker then its 12mA peak output current will be 8.5mA RMS resulting in a very low maximum output power of only 0.0006W. Hold the speaker directly to your ear to faintly hear it.