Found in a Popular Electronics from the 90s, this circuit uses common components with several operational options, including the use of an optocoupler that allows its application in a shield.
This 6V regulator with FET was found in an old Electronic Design. FET and transistor admit modern...
Frequency Indicator (CB6342E) This simple circuit was found in an Exar publication from the 1970s....
The circuit shown in the figure differs from the previous one (CIR8909) in that it can be...