8. Car Radio

This circuit is on Circuitverse: https://circuitverse.org/users/151941/projects/car-radio

This is a mux circuit

It simulates a car radio signal with 8 radio station signals. I included a previous portfolio project to simulate a 24 hour cycle of time as well. Essentially, this circuit utilizes a mux to accept inputs from radio stations, so a 1 signal represents an active radio and a 0 represents an inactive station. These 8 inputs include 3 24 hour radios, and 5 timed radios, the exact time schedule is below.

Radio Schedule(24 hour clock):

0=6-12 1=6-12

2=24 hr 3=24 hr

4=12-19 5=24 hr

6=12-19 7=17-23

The control bits come from a keypad made with an encoder and d flip flops to hold the encoder output as I am using buttons which correspond to each radio for the encoder inputs, additionally, an or gate is used with all the buttons to activate the clock of the d flip flops for each button press. This output then acts as the control bits to the mux to select a station. The stations function on the schedule above using 8-1 muxes all with ABC as the control bits from the ripple counter. This ripple counter now also includes a display for the time in the form of two 7 segment displays acheived through the use of eprom on circuitverse.

Finally this circuit has an enable bit which acts as the on off button for the radio which is anded with the final output.

The work for the radio station equations is below:

Equations(A-E come from 24 hour ripple counter):

6-12= A'B'CD+BD'E'+BC'

12-19=BC+AB'C'

17-23=(A)(C+D+E)