This circuit for an optical audio link using LED or LASER was found in a 90s QST magazine. The circuit can use operational amplifiers like the 741.
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...