Found in an Electronic Design of 1964 this circuit has a control for the frequency and another for the active cycle the signal. The bipolar transistor can be a general-purpose type.
This sensor circuit for currents of the order of nanoamperes was found in an American...
This circuit was obtained from a 1964 magazine and has some interesting features such as the input...
Suggested by a 90’s Radio Electronics, this circuit automatically activates the recording switch of an...