Revised 2-1-07 6:45 p.m.

Lab GB1-8: PV Vent Motor Controller,
and Misc. Additional Indicator Lights
20 points 40 points
OEES 160

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 Description of Motors and Sensors

  • There will be two ventilation doors.
  • Each door will be operated by its own 12 VDC permanent magnet motor.
  • For each door, there will be one sensor to indicate that the door is closed and another to indicate that it is open.

Logic Labels

Door 1:
  • D1F  1 = Run  motor forward to open the door. (Output)
  • D1R  1 = Run motor in reverse to close the door. (Output)
  • D1C  1 = Door is closed. (Input)
  • D1O  1 = Door is fully open. (Input)
Door 2:
  • D2F  1 = Run motor forward to open the door. (Output)
  • D2R  1 = Run motor in reverse to close the door. (Output)
  • D2C  1 = Door is closed. (Input)
  • D2O  1 = Door is fully open. (Input)
Indicator lights:
  • ET     1 = Extreme temperature (too hot or too cold)
  • FD     1 = Freeze danger

Design Procedure

As you're creating the circuit, insert text to show logic labels and Boolean expressions at the following points:
  • Gate inputs.
    • If the signal is coming from a sensor, use the sensor's label.
    • If the signal is coming from another gate, show a Boolean expression that describes what sensor conditions will produce a high at this point.
  • Intermediate gate outputs (those not going to motors or lights).
    • Boolean expression
  • Final outputs.
    • Show both the output label (DF, DR, S, E, etc.) and a Boolean expression that describes what sensor conditions will produce a high at this point.
Get handout GB1-8 page 3 from me.

Use truth tables and Veitch diagrams to do the following, and then modify the previous Multisim circuit (for the door, shutdown, and error light) as needed:
  1. Have four door outputs (D1F, D1R, D2F, and D2R) instead of the one output (D) previously used.
  2. Eliminate the DS (door shut) input previously used, and use the door closed and door open sensors described in the Logic Labels section above.
  3. Apply the following rules to each motor separately:
    • Run the motor forward if it's hot inside the box, and the door-open sensor is low. (This will open the door.)
    • Run the motor backwards if it's not hot in the box, and the door-closed sensor is low. (This will close the door.)
    • Don't run the motor at all if the correct door sensor is high for the temperature condition present.
      • If the box is hot and the door is open, don't run the motor.
      • If the box is not hot and the door is closed, don't run the motor.
    • Don't run the motor if both the open and the closed sensors are high (because there's a sensor malfunction).
    • If both the hot and the cold sensor are high, close the door (just in case it really is cold in the box, and the hot sensor has failed)
In addition to the above modifications, add circuitry to create the following outputs:
  1. A battery low light. Simply connect it to the B (battery low) sensor.
  2. An extreme temperature light, ET (too hot or too cold). Use only one light (to indicate either too hot or too cold).
    • Knowing the outdoor temperature, it should be pretty obvious whether the enclosure is too hot or whether it's too cold.
  3. A freeze danger light, FD: Both B and C (too cold) are high.

For any experiments involving, the PV system, be sure to save your files. In addition to having them in your folder in My Documents, put a copy onto a flash drive or floppy. (If  you're using a floppy, be extra careful to always have an up-to-date copy of your files in My Documents on the hard drive. Floppies often fail.)
 
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