We found this circuit in a Linear Technology documentation from the 80's. It has a demodulator, being suitable for links and remote controls. Note the unusual type of detector configuration.
This circuit is designed to analyze the distortion of an audio signal. We found it in an article in...
Using a BA1404 integrated circuit this small FM stereo transmitter was found in a Radio...
This traditional doubler configuration with the 555 can be found in other articles on the author’s site....