This circuit is from the National Semiconductor's Linear Applications Handbook of 1994. The circuit can be implemented with equivalent operational. The detected voltage is given by the diode.
This blocking oscillator circuit was found in a book by Rufus Turner from 1954. The circuit uses...
This is a configuration much explored by assemblers, being found on this site in dozens of similar...
This circuit is from a June 1992 Radio Electronics. The circuit is for 4.5 MHz signals from old...