T120     08 0320

Lab HC19-12 Two Limit Switches
Multisim & Real Components      30 points
OEET 120

Back to Main Page
 Multisim Portion
  • Click here to download a file that contains a partial circuit.
  • Add wires (and rearrange components) to achieve operation as follows:
    • When relay K1 is energized, the motor should run counterclockwise.
    • When relay K1 is de-energized, the motor should run clockwise.
    • Relay M1 should be energized whenever relay K1 is energized (and be de-energized the rest of the time).
    • When the right limit switch is depressed, relay K1 should energize and stay energized until the left limit switch is depressed.
    • When the left limit switch is depressed, relay K2 should become energized. 
Hints:
  • Think of relay K1 and the two limit switches as being like the relay circuit we constructed in the past for allowing us to use momentary pushbuttons as the START and STOP buttons for a motor. Recall that the START button was normally open, and the STOP button was normally closed. 
  • The normally closed contacts of relay K2 will be like the normally closed STOP button.

Real Component Portion
Use 12-volt relays to implement the circuit you simulated above. Instead of the diodes and lights, use the motor that drives our limit-switch mock-up. And, of course, use the two limit switches on the mock-up as the limit-switch pushbuttons in your simulation.

You'll need two power supplies: a 12-volt supply to run the relays, and a 4-volt supply to run the motor.

CAUTION: Be sure not to use more than four or five volts to run the motor. 12 volts would probably instantly burn out the motor.
 
Back to Main Page