This 100 MHz bridge circuit was found in an American 1970s documentation. The supply voltages are not indicated, nor are the tubes.
Although the system is experimental and should not be adopted by the arrival of digital radio, for those...
Found in an Electronic Design from the 80s, this single cell charger uses an integrated circuit...
Found in an Elektor from the 90's, this double door-bell drive circuit switches a relay by...