In: Electrical Engineering
What physical device in the bathroom resembles the liquid level switch? 12. Draw logic for a motor starter control circuit for a motor that is either off, on forward or on reverse with a selector switch.
The flush mechanism resembles the liquid level switch. Whenever the tank is full the switch closes the valve and so water cannot fill the tank but when someone uses the flush the valve opens up and water gets filled in the tank untill it's full again.
12. We see that we have three states of the motor. i) The motor is off. ii) The motor is on in forward direction.
iii) the motor is on in the reverse direction. We need atleast two bits to encode three states. We respectively assign 00, 01 and 10 states. ( 11 being a don't care). The inputs are i) on/off switch and direction switch. Let us assign 1 for on and 0 for off Condition for the on/off switch. Also let 0 corresponds to forward direction and 1 corresponds to reverse direction. The truth table would thus look like so.
On/Off switch(A) | Direction switch(B) | Out1 | Out2 |
0 | 0 | 0 | 0 |
0 | 1 | 0 | 0 |
1 | 0 | 0 | 1 |
1 | 1 | 1 | 0 |
Solving the above truth table we get Out1 = A.B
And Out2 =A.B'
The logic circuit looks like so: