This circuit was found in the July 1986 issue of Radio Electronics magazine. The circuit has a loudspeaker warning system. The sensor is the ceramic capacitor C1 which acts as a transmission line.
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...