This indicator or logic probe was found in the April 1979 Radio Electronics magazine. The integrated circuit is the 555 and the FET can be any general-purpose type.
In the figure we have the transmitter of a data transmission system with optical fiber suggested by...
This circuit was found in a 1969s American documentation. With modern components, it can be used...
The maximum input voltage of this circuit is 20V and the output current is 250 mA. The circuit is from...