This circuit with the CA3059 was found in the July 1995 Elexctronics Now magazine. The signal must be DC, and the circuit is not isolated from the mains.
This circuit was found in a Mullard transistor manual from 1960. Note the symmetrical power...
This amplifier step with a transistor has an input impedance of 100k to 10 M. The transistor can be any...
I found this little signaling transmitter in old American documentation. The circuit has a good...