This circuit operates from 25 to 65 kHz depending on the transducer used and the settings. We found it in the Radio Electronics magazine of July 1985. The 9V to 12V power supply is not given.
This broadband amplifier was found in an Elektor from the 90's. The gain is 10 dB with a noise...
Found in Linear Technology documentation from the 90s, this circuit uses an operational amplifier...
This simple circuit that interrupts the supply of a 12 V load in the event of an overvoltage was found in...