Prelab Exercises

1.   The MOD-8 counter in Figure 5 provides the select inputs to the MUX and also to the DEMUX on the remote monitoringpanel.
Explain what happen to the MUX and DEMUX when the MOD-8 counter sequences from 0-7.

2.    Explain why pin E of 74LS151 MUX need to be grounded.

3.    Explain why pin 3 is connected to +5 V and pin 2 to ground of the 74LS138 DEMUX.

4.   The status of each door can be monitored by running wires from each door switch to the LEDs and the monitoring panel.
     Explain why the monitoring system in Figure 5 using MUX and DEMUX is actually a better approach.

5.    Design a MOD-8 counter from a 74LS93 IC for the MOD-8 CTR of the security monitoring system.

6.    Multiplexer circuits find bumerous and varied applications in digital system of all types. Name 3 applications of multiplexer in digital systems.