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.
We found this circuit in an old American publication. The transistors can be BC558 and diode 1N34....
This simple circuit operates with only 1.5 volts of a battery and detects low resistance making a...
The cascade connection of two flip-flops allows division by 4, as shown in the figure. Note that...