The project could be ordered in kit form or fully assembled, or the reader could source the parts and design as the articles contained a circuit diagram.
The circuit diagram of the model 102 shows the direct connection of the receiver to the line, while the transmitter was induction coupled, with energy supplied by a local battery.
These partial derivatives can be associated with physical quantities (such as capacitance, resistance and inductance), and a circuit diagram relating them can be formulated.