Hands off

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Nobody talks about it, but everybody knows what that is. We’re going to bring you to the edge of your seat, today on Engineering Works.

It’s something everybody grows up with. Your mother probably told you several thousand times — wash your hands after you flush the toilet.

Now, let’s find out how some clever engineering makes it so you don’t have to remember to flush in public restrooms.

It’s all about light. A special kind of light, known as infrared in this case. You can’t see infrared light. Its frequency and wavelength, two things physicists use to describe light, are outside the range of light our eyes can see.

Using infrared light, engineers have developed valves that flush by remote control. That means you don’t have to touch that germ-covered handle that your mother warned you about.

This remote-controlled flush valve looks like a little black box with a tiny window in the front. Inside are two important devices. An emitter, and a receiver. The emitter shines out a constant beam of infrared light. When you get in the way of that beam, part of it is reflected back and the receiver sees it. If the receiver sees that reflected light for more than a few seconds, an integrated circuit tells the flush valve to get ready to go.

Then, when the receiver stops seeing the reflected light, it trips a switch and the toilet flushes. The system saves water and promotes good sanitation.

So, the next time you’re in a public restroom and the toilet flushes by itself, you know why. But don’t forget to wash your hands.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.

on, off, on, off, on, off …

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Get out your magnifiers. We’re going to take a look at the tiny beginnings of the Information Age: transistors. Today, on Engineering Works!

Transistors might be the Rodney Dangerfields of the Information Age. They do the work, but the microchips get the credit. As Rodney might say, microchips wouldn’t be nothin’ without transistors.

Engineers at Bell Laboratories built the first one in 1947. Transistors act as both on-off switches, stopping or starting the flow of electricity, and as modulators or amplifiers, increasing the electrical signal. Think of the dimmer switch in your living room. It turns a light on and off, and dims and brightens it.

In a microchip, engineers put together millions of transistors in a particular pattern that does whatever task the chip is intended to do. Arrange the transistors one way, and you get processors that make calculators calculate and computers compute. A different pattern gives you the chip that keeps time in your digital watch or microwave oven. Maybe you need a sensor to monitor temperatures or detect intruders: design a different pattern and it’s yours.

By themselves, transistors can’t do much. But put together enough of them in the right patterns and you can do big jobs and complex calculations; fast, too. Each transistor switches on and off 100 million times a second.

It’s about time to switch off this week’s Engineering Works! See you next time.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.

Perpetual Motion

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Nothing keeps on going and going, forever. Or does it? We’ll take a look. Today, on Engineering Works!

We all know that the Energizer Bunny only exists in commercials. But a lot of folks like the idea of something that goes on and on forever — perpetual motion — and they’ve been looking for ways to do it for real for a long time.

Quite a few people have designed perpetual motion machines. They haven’t worked. Basic physics gets in the way – the idea known as conservation of energy. You’ve got to put something in to get something out. Everybody knows that, but people keep trying.

An Indian mathematician and astronomer named Brahmagupta seems to be the first to design a perpetual motion machine – about 1,400 years ago – a wheel with hollow spokes full of mercury. The idea was that as the wheel spun, the mercury would shift and keep the wheel spinning. He never actually built one. Renaissance genius Leonardo da Vinci took a shot at perpetual motion, too. It didn’t work for him, either.

The latest seems to be a company in Ireland. They say their engineers have designed and built a machine that’s spun by magnets, without using outside energy to do it. They say a panel of scientists has checked it out. But they keep putting off the date they’re going to show everybody else how it works. Hmmm.

Perpetual motion or not, we’re running out of energy here. See you next time.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.

Hoover Dam

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We’ll visit an engineering marvel that really is your dam business – Hoover Dam. Today, on Engineering Works.

You’ll find Hoover Dam on the Colorado River, on the border between Nevada and Arizona. When it was completed, in 1935, it was the biggest dam in the world. And it changed the American West forever.

Without the water and hydroelectric power it provides Los Angeles, San Diego and Phoenix, the western end of the Sunbelt might have stopped in Dallas. Without it, Las Vegas would still be a dusty little town in the desert.

Building Hoover Dam was such a big project that it took six construction companies to pull it off. More than 200 engineers and 7,000 workers started on it in 1931. The first step was to move the Colorado River out of Black Canyon. Then they used four tons of dynamite to blast foundations and tunnels into the canyon walls. They started pouring concrete in 1933. When they were done, two years later, the dam stood more than 700 feet above the bedrock. They used enough concrete to pave a two-lane highway from San Francisco to New York City.

The reservoir behind the dam – Lake Mead – is a National Recreational Area that extends more than a hundred miles upstream toward the Grand Canyon. Hoover Dam was declared a National Historic Landmark in 1985 – its 50th anniversary. More than seven million people visit each year.

We’ll wrap up our visit now.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.