OEET 120

T120 08 0214

HB14-11 Burglar Alarms
Multisim & Real Components 30 points
OEET 120

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Multisim Portion

In Multisim, go to the blue Basic Family icon and choose Virtual Combination Relay.
Modify the relay shown above so that it has a coil inductance of 1 nH, a coil resistance of 1 kohm, an on current of 10 mA, and an off current of 5 mA.
Create a regular schematic (as opposed to one that uses ladder diagrams).
Omit the normally-closed pushbutton A, and connect the above components so that you get a circuit that functions as follows:

If either button B or C is pressed, the light will go on.

Now, include button A and modify the circuit so that it will work as follows:

If either button B or C is pressed, the light will go on and stay on until button A is pressed.

Make a copy of the relay from the previous circuit so that you now have two relays, as shown above.
Connect the above components so that you get a circuit that functions as follows:

If either button B or C is pressed, the light will go on and stay on until pushbutton A is pressed, at which point the light will go off and stay off. Notice that B and C are normally-closed buttons.

Hints:

Connect the left-hand relay so that its coil is energized all the time, except for when button B or C is pressed.
If you press button B or C, the left relay will become de-energized. When you release the button you pressed, the relay will become energized again.
When the left-hand relay is de-energized, the right-hand relay should be energized.
Once the right relay has been energized, it will remain energized until someone presses the Reset button.

Real Component Portion

Caution: Before you power-up your circuit, be sure the power supply is set for 12 volts. Otherwise, you may burnout a relay coil.
Using Heath 12 V. relays (as shown above), connect the two-relay circuit that you simulated in Multisim.
Instead of using pushbuttons, use wires inserted into the breadboard.

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