This simple circuit with a 5V regulator was found in an American documentation from the 90's. The output voltage is adjusted in a trimpot.
This is the basic configuration of an operational amplifier sample & hold circuit. The FET and...
Found on 80's Popular Electronics, this circuit uses an uncommon integrated today. Programming is done...
Found in a 1968 Mullard manual, this circuit can function as an infrared audio link. The...