Design Project: Telegraph System

Basic Electricity

PDF Version
  • Question 1

    What voltage will you choose to use for each of the station batteries?

    Reveal answer
  • Question 2

    What resistor values will you choose for the “dropping” resistors in series with the light-emitting diodes? Remember that these resistor values will depend on the voltage and current ratings of the diodes, as well as the chosen power supply voltages.

    Reveal answer
  • Question 3

    Explain how it would be possible to have more than two telegraph stations working on your system. Where would you connect the third, fourth, and fifth stations? Would the station designs have to be changed in order to accommodate more than two stations? Will your working voltage have to change?

    Reveal answer
  • Question 4

    Modify your telegraph station design to incorporate two indicator lights: one for transmission and one for reception. How could the stations circuitry be changed such that there would be separate lights to indicate different directions of data travel?

    Challenge: modify the circuit so that the “sending” light only illuminates if the other station’s “receive” light actually has a complete circuit. In other words, if the receiving station’s “receive” light fails open and does not light, the transmitting station’s “send” light should not light either!

    Reveal answer