A cold dark alarm is desirable for gardeners because it means they can be alerted if their crops are in danger of being damaged. One way of making one is shown below. The alarm is switched on with a switch and the alarm sounds if it is dark AND cold.
The output at each stage is shown below.
|
A |
B |
C |
P |
Q |
R |
|
1 |
1 |
1 |
1 |
0 |
0 |
|
1 |
1 |
0 |
1 |
0 |
0 |
|
1 |
0 |
1 |
1 |
0 |
0 |
|
1 |
0 |
0 |
1 |
0 |
0 |
|
0 |
1 |
1 |
1 |
0 |
0 |
|
0 |
1 |
0 |
1 |
0 |
0 |
|
0 |
0 |
1 |
0 |
1 |
1 |
|
0 |
0 |
0 |
0 |
1 |
0 |