Low active cycle pulse oscillator (CB8920E)

Short pulses can be found in this 90's EDN circuit. The load is 50 ohms and the transistors are from that time.

Current sensor with 100 M ohm input (CB9663E)
This sensor circuit for currents of the order of nanoamperes was found in an American...
MW Experimental Radio (CB4517E)
This circuit was obtained from a 1964 magazine and has some interesting features such as the input...
Automatic call recorder (CB8656E)
Suggested by a 90’s Radio Electronics, this circuit automatically activates the recording switch of an...