============================================================= "HOME TECH": The Inner Workings NewScience ------------------------------------------------------------- The Toilet Yes...those tales you've heard are true. The toilet was first patented in England in 1775, invented by one Thomas Crapper, but the extraordinary automatic device called the flush toilet has been around for a long time. Leonardo Da Vinci in the 1400's designed one that worked, at least on paper, and Queen Elizabeth I reputably had one in her palace in Richmond in 1556, complete with flushing and overflow pipes, a bowl valve and a drain trap. In all versions, ancient and modern, the working principle is the same. Tripping a single lever (the handle) sets in motion a series of actions. The trip handle lifts the seal, usually a rubber flapper, allowing water to flow into the bowl. When the tank is nearly empty, the flap falls back in place over the water outlet. A floating ball falls with the water level, opening the water supply inlet valve just as the outlet is being closed. Water flows through the bowl refill tube into the overflow pipe to replenish the trap sealing water. As the water level in the tank nears the top of the overflow pipe, the float closes the inlet valve, completing the cycle. From the oldest of gadgets in the bathroom, let's turn to one of the newest, the toothpaste pump. Sick and tired of toothpaste squeezed all over your sink and faucets? Does your spouse never ever roll down the tube and continually squeezes it in the middle? Then the toothpaste pump is for you! When you press the button it pushes an internal, grooved rod down the tube. Near the bottom of the rod is a piston, supported by little metal flanges called "dogs", which seat themselves in the grooves on the rod. As the rod moves down, the dogs slide out of the groove they're in and click into the one above it. When you release the button, the spring brings the rod back up carrying the piston with it, now seated one notch higher. This pushes one-notch's-worth of toothpaste out of the nozzle. A measured amount of toothpaste every time and no more goo on the sink. Refrigerators Over 90 percent of all North American homes with electricity have refrigerators. It seems to be the one appliance that North Americans can just not do without. The machine's popularity as a food preserver is a relatively recent phenomenon, considering that the principles were known as early as 1748. A liquid absorbs heat from its surroundings when it evaporates into a gas; a gas releases heat when it condenses into a liquid. The heart of a refrigerator cooling system is the compressor, which squeezes refrigerant gas (usually freon) and pumps it to the condenser, where it becomes a liquid, giving up heat in the process. The condenser fan helps cool it. The refrigerant is then forced through a thin tube, or capillary tube, and as it escapes this restraint and is sucked back into a gas again, absorbing some heat from the food storage compartment while it does so. The evaporator fan distributes the chilled air. In a self-defrosting refrigerator/freezer model, moisture condenses into frost on the cold evaporator coils. The frost melts and drains away when the coils are warmed during the defrost cycle which is initiated by a timer, and ended by the defrost limiter, before the frozen food melts. A small heater prevents condensation between the compartments, the freezer thermostat turns the compressor on and off, and the temp control limits cold air entering the fridge, by means of an adjustable baffle. Smoke Detectors Is your smoke detector good at scaring to death spiders who carelessly tiptoe inside it? Have you ever leapt out of the shower, clad only in you-know-what, to the piercing tones of your alarm, triggered merely by your forgetting the close the bathroom door? Is it supposed to do this? There are two types of smoke detectors on the market; the photoelectric smoke detector and ionization chamber smoke detector. The photoelectric type uses a photoelectric bulb that shines a beam of light through a plastic maze, called a catacomb. The light is deflected to the other end of the maze where it hits a photoelectric cell. Any smoke impinging on this light triggers