# Homework Help: Creating a Simple Room Security System

1. Oct 20, 2012

### Mosaness

1. The challenge is to create a simple security system using only resistors, a very thin wire, 12 AAA batteries, and a piezoelectric buzzer.

2. The attempt at a solution

I recall reading that if a resistor is placed mid-wire in an alarm system, it will not detect any problems, such as a person trespassing or breaking in.

I did a little bit of research and came across a pdf that highlights a few points towards building an alarm.

My input source would be the batteries to provide a voltage to power the alarm. The output would be the piezoelectric buzzer. What remains is designing the system.

Can someone help me out with this? I need to do this extra credit to salvage my grade in that class.

2. Oct 21, 2012

### CWatters

So the idea is that when someone opens a window it breakes the thin wire and that sounds the alarm?

So design a circuit that sounds the alarm all the time but which can be turned off by shorting out a component with a wire.

3. Oct 21, 2012

### Mosaness

That's pretty much the idea. Sort of like a burglar alarm. The only components allowed are:

1) Resistors of 1k
2) Wire w/ resistance of 1ohm
3) A piezo electric buzzer.
4) 12 AAA 1.5V batteries

My initial rough draft was a square with a ground at the leftmost corner and a resistor at the remaining three corners. There were 3 AAA batteries that I put in the middle of one side to act as the voltage source. I was thinking that the side with the batteries could be the entry point.

4. Oct 21, 2012

### CWatters

Can you draw that. You didn't mention thepiezo in your description of the circuit.

I see no need to distribute components around the room on a simple design. Is there more to the question? Such as a need to detect tampering?

5. Oct 21, 2012

### Mosaness

I can show you the PSPICE diagram that I created for it. I'll attach that. That alarm is suppose to attack as a sensor for any window that is broken or opened.

#### Attached Files:

• ###### PSPICE.jpg
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6. Oct 22, 2012

### Mosaness

No one has any suggestions?...

7. Oct 22, 2012

### Simon Bridge

What about the suggestion in post #2?

8. Oct 23, 2012

### CWatters

I can't see the top of that diagram but there doesn't appear to be a buzzer in the circuit but if there is it appears to sound all the time until the circuit is broken.

9. Oct 25, 2012