Found in RCA documentation from the 1960s, this 60 V regulator has a 100 V input and a current of 1 A. The transistors are from that time. One can try to use modern equivalents.
This circuit multiplies the input voltage by 3 and can work with up to 12 V input. The current is a few...
This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at...
This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The...