Response to the following problem:
The circuit of Fig. P4.16 can be used in a signaling system using one wire plus a common ground return. At any moment, the input has one of three values: +3 V, 0 V, -3 V. What is the status of the lamps for each input value?
(Note that the lamps can be located apart from each other and that there may be several of each type of connection, all on one wire!)
