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Island 6 Snap Circuits Designing Alarm Systems


POP students will learn about specialized electrical components called sensors and integrated circuits. Then apply their new knowledge as they build a variety of working alarm system circuits!


Snap Circuits-Designing Alarm Systems

What is it?

Integrated Circuits:

If you have used Snap Circuits before, you are probably familiar with the size and space required to connect your circuits. Now try to imagine shrinking one of your circuits that measures 6” x 10” into a tiny space so that thousands - or even millions - of electronic parts can fit on the end of your finger. That is basically what happens when electrical engineers design and make integrated circuits.

An integrated circuit (IC) or microchip is an electronic circuit manufactured in a semiconductor material. Integrated circuits are used in virtually all electronic equipment and have revolutionized the world of electronics. The miniaturized circuits that are embedded into microchips give the electronic devices you use everyday tremendous capabilities at a very low cost. Have you ever received a musical birthday card? It used an IC.

Some of the electronic components in your Snap Circuit kit are using microchip technology. If you look closely at the name on these components, you will see that they all end with IC. You will be using these integrated circuits (IC) components in your alarm circuits.

Types of Sensors:

Sensors are specialized electronic components that respond to an environmental factor. There are sensors that respond to light, sound, temperature, motion, smoke, pressure, magnetic fields, and more. Most alarms rely on some kind of sensor that acts as a switch to turn the alarm signal on.

There are two types of sensors in your Snap Circuits kit.

The first is called a photoresistor. As the name suggests, it is a resistor that is sensitive to light. In the dark, it has enough resistance to block all current flow. When a bright light shines on it, its resistance drops and electrical current can flow through the circuit. Different levels of light will lead to different levels of resistance.

The second is a sound sensor called a whistle chip. It has two thin metal plates inside. In its normal state, the two plates do not touch, so the circuit is “open” and electricity cannot flow. The movement of air from a loud noise, like a clap, pushes the plates together, briefly “closing” the circuit and allowing electricity to flow across it.

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