How to Reduce or Prevent Condensation in Your Home

Condensation occurs when air hits a cold surface. Air has a limit to the amount of water it can hold in suspension and the amount of water in the air is known as the relative humidity (measured as a percentage). Once air becomes saturated, the relativity humidity has reached 100%. Now as the temperature becomes lower, air can hold less and less water. Condensation occurs when water laden air hits a cold surface, reducing the temperature of the air. This could be glass in windows, cold tiles or metal surfaces. These surfaces are either colder than other surfaces in a room or are of high thermal conductivity so that heat is sucked out of the air. In any case, the air temperature drops to the extent that it can't hold moisture any more and it is deposited on the surface.
To avoid condensation you have several options. Firstly you can vent moisture laden air (e.g from cooking in the kitchen) so that it doesn't end up in rooms. You can do this by using extractor fans or simply opening windows. Portable gas heaters produce lots of water vapour and should be avoided. Another option is to raise the temperature in the room. This makes surfaces warmer so that moisture doesn't condense out. Double or triple glazing also helps because the external surface of inner panes of glass is not in contact with air outside the house. Removing sources of moisture also helps. This includes house plants and damp clothing. Clothes in the washer should be kept there with the door closed until they are transferred to a drier, or hung outside. Drying clothes in rooms or on radiators transfers water to the air where it inevitably condenses out if windows are closed and the room temperature drops. Yet another way of reducing condensation is to use a dehumidifier. This appliance works by circulating air over chilled coils. This causes moisture to drop out of the air (just like it does on your windows) and collect in a reservoir tank.

How Can a Freezer be Defrosted Quickly?

You can wipe over the ice with a cloth or towel soaked in hot water. This will soften the ice enough so that it can be scraped off. A plastic lifter like the type which is used with non stick frying is useful for getting in under the ice and prying it off. Don't use metal scrapers if the inner surface of your freezer has a foil coating as it can lead to damage. A basin of boiling water placed at the bottom of a chest freezer also helps to accelerate the melting of ice (After having pulled the plug and removing all food)

Why Do Computers Make Noises?

Several things in a computer make noises. First of all, the head in a disk drive makes some noise as it moves in and out over the aluminium platters in the drive during disk access. The head is actuated by devices called stepper motors which can rapidly move the head towards the center or edge of the disk. The motor which drives the platter/platters in a hard disk may also make some noise.
There may be one or more fans in a computer for cooling the electronics. The microprocessor (CPU) is likely to have a fan and there will also be a general purpose fan for drawing air through the machine to cool it. Usually there is a temperature sensor, and the fan cuts in and out as the temperature rises above and falls below threshold levels (just like the way an electric cooling fan for the radiator may turn on when a vehicle with the engine running is stationary for any length of time). Alternatively the speed of the fan may be varied, depending on the amount of processing of data which is taking place. It occasionally happens also on desktop computers when a fan gets old, the bearings can wear and the fan becomes noisy.
The power supply may also make some noise. When a current passes through electronic components, sometimes, electric or magnetic fields can cause movement (e,g, if you hold an older style, non switched mode, power adapter up to your ear, you can hear it humming). A sudden demand for power from the supply could cause clicking sounds.
Other clicking sounds can be caused by thermal expansion/contraction as the computer warms/cools (like the way gutters or roofs can creak when the sun comes out).
The old style dial up modem sounds were due to the "tones" which were sent down the line. Digital bits can't be sent directly down a phone line. Instead, various tones or sound frequencies were used to represent "ones" and "zeros".
As regards cooling fans, there is no harm installing a utility on your computer which displays the core temperature of the CPU or (CPUs if the machine is dual core or quad core). I have a utility called core temp installed which displays the temperature on the taskbar. It will power down the machine or display a warning if the temperature exceeds a set value. If you have a laptop, leaving it on a sofa can cause it to overheat, because the air intake may be under the machine and can get blocked. Another tip is to setup a laptop running on battery power so that it goes to sleep after a few minutes of inactivity.

What is a Neon Glow or "Phase" Tester?

A neon glow tester, sometimes called a "phase" tester is a device used to detect mains voltages. The neon capsule in the device is usually sensitive to voltages from 90 volts upwards. Contact must be made with a live terminal for the neon bulb to glow. When doing electrical maintenance work, a neon tester can be used to double check power is turned off after switching off a breaker. Neon testers are commonly available in the form of a flat screwdriver whose blade is sized to suit the screws in electrical fittings.
Newer type hand held electrical testers such as the Fluke VoltAlert use an electronic detection circuit which activates an LED when the tip of the tester is in close proximity to a live terminal or power cable, actual contact is not necessary. These testers are useful for detecting presence of voltage e.g in a power flex or on the output of a breaker. However if the tip is too far away, the LED may not light up, giving the false impression that a circuit is not live. So they should never be used to test for absence of voltage. A neon tester should be used for absolute certainty when testing (and the tester should be pre-checked by touching it against a live terminal , e.g. the outlet of a socket to ensure it is working properly).