TV's, HOME THEATRE AND ELECTRONICS
Various info about electronic stuff around the house
WHERE TO PUT A TV
Although it seems that deciding where to put a television is a bit of a no-brainer, there are actually quite a few things to take into account in order to give you a comfortable and healthy viewing experience.

AESTHETICS
From a lady's point of view, the TV must fit in with the aesthetics of the room: it must not clash with any other furnishings, or be untidy, or make the room seem out of balance. It should compliment the furnishings of the room if possible.

TECHNICAL: POWER
From a guy's point of view, there are a number of technical issues. Firstly, you need to get power to the TV, so if possible it should go near an electrical outlet point, or else (to keep the room neat) one would have to put in some power skirting, or "trunking" to house an extension wire to a where the TV is going to be.

PICTURE
Next, you need to get picture to the TV, either from an antenna or dish, or from cable. If you are using an antenna, it is best to keep this cable as short as possible to minimise losses in the cable. If you have a very strong incoming signal, then this issue is not so important. If the signal is bad and the cable has to be long, get some low loss cable to compensate. Note, however, that low loss cable is quite expensive.

GLARE
Glare on the screen from windows, lights and reflections is a very important issue, as glare reflecting off the screen into the viewers eyes is not only irritating, it's also bad for you, causing eye strain, headaches and vision problems. Make sure that the TV screen does not face any windows or bright lights, or pick up strong reflected light from surfaces like glass or metal. Sometimes just tilting or angling the screen slightly can eliminate a lot of glare.

HEIGHT
Try and get the TV screen at the same height as your eyes will be when you are viewing it, at which time you would normally be in a seated position, as this will be the most comfortable height for viewers.

HEAT
Make sure that the TV has enough ventilation, by leaving enough space around it. The TV installation manual will give you the exact space to leave, but normally 5 to 10cm or 2 to 4 inches on each side, and at the back, should do it. If it's a flat wall mount screen, space at the back is not necessary, but leave some air space at the top of the screen, and at the bottom if there are air intake vents there.
So as you can see, there are quite a lot of things to consider, but they do help to give you a better viewing experience, and lengthen the life of the TV set.

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ARE CELLPHONES DANGEROUS?

Cellphone usage worldwide numbers in the billions. If there is a possibility of injury from these devices, then a lot of people will be affected.

A cellphone is actually a radio transmitter and receiver. It sends and recieves radio frequency electromagnetic waves. The received signals are fairly low level, so I will concentrate on the signal transmitted from the cellphone.

Cellphones transmit mainly at frequencies of 900, 1800 and 1900 Megahertz (MHz).  A microwave oven cooks food using a frequency of 915 MHz or 2450 MHz. In other words, the food is not fussy about what frequency you use, as long as it's in that range, say 900 to 2500 MHz. Which means, cellphones use Microwave Oven frequencies.

A microwave oven puts out a power of about 1000 watts, on average. If you put your head in a microwave oven, it will take about an hour to cook to a nice sizzling crisp.

A cellphone transmits at a power of about 3 watts, and it self adjusts it's power continually to compensate for poor signal paths, up to a maximum of 5 to 7 watts. Not much, but there's a twist...

A microwave oven spreads it's radiation over the whole oven cavity, so that the food is cooked uniformly.

A cellphone has a tiny, array antenna, measuring maybe 2 or 3 cm in length, and it's right next to your ear. So 5 watts of power is radiating into your head into an area of perhaps 3cm by 0.75cm. That's a lot of power when concentrated in such a small area.

The cellphone manufacturers have said that they have put "shields" into their phones to keep radiation risks to a minimum.

If you turn around while making a call, does the call cut out or the audio disappear at any time? No, it doesn't. High frequency radio waves, like light waves, travel in a straight line. If your head got in between the cellphone and the cell transmitter tower, then the signal should be blocked (shielded) by the shield in the phone, as the waves can't bend once they've left the phone.

Which means that those microwaves are going through your head, all the time.
Whenever you're "on the phone," you are being microwaved just like the roast in your microwave oven.

So What Can You Do?

If you've got a handsfree kit, use it if it's practical. Rather don't use bluetooth - it also transmits radiowaves close to your head, albeit at different frequencies and at a lower power.

If your phone has a loudspeaker, switch it on and speak at a distance. The guy on the other side will still hear you perfectly.

Buy phones with a low Specific Absorption Rate (SAR)

Don't let children make long calls. Their soft skulls are much more affected than the hard heads of adults.  (See "The Stewart Report.")

Swop ears every minute or so, to give your head time to "cool down" on that side.

Don't hold the phone next to your ear while connecting - this is when it transmits at maximum power.

Avoid making calls in weak reception areas, as the cellphone will boost it's output power to make sure it stays connected.

Keep your conversations short.

Use SMS's whenever possible.

Avoid sleeping with a cellphone under your pillow. Cellphones transmit even when you are not using them, exchanging data and checking signal strength, at regular intervals.

Avoid carrying the cellphone close to your body. This applies especially to the breast pocket of people with heart problems.

Use a landline whenever possible.

Many people have proven health problems from cellphone usage, brain tumors being the most common, followed by loss of memory, impaired brain function, cancer of the salivary glands, and other symptons. Usually these symptons take a few years to surface.

By taking the simple precautions listed above, we can potentially save our lives. Tell your family and friends too. There's a lot of people out there who need to be aware of these facts.

How a Radio Program Gets From The Studio DJ To Your Radio

Listening to music on the radio is as normal as eating breakfast or combing your hair. It's an integral part of most people's day. But if you stop a moment and think about it, it is a bit of a miracle how music can come through the air wirelessly and play in your kitchen. This is how it works...

THE STUDIO
The DJ in the studio talks into a microphone, and plays CDs, and these stereo sounds are sent to a mixer desk, which combines all these signals and gets their volume and tone right. These sound signals then go to an audio processor, which adds other signals like traffic info, a pilot tone, RDS signals and possibly NICAM signals, among other things. The stereo tracks are melded into an encoded stereo, and then all these signals are cleverly combined into a single channel called baseband.

THE LINK
This signal is sent to a digital link, which digitises the baseband, adds it to a very high frequency carrier, and then transmits this over the air to a nearby transmitter station, which is normally situated close by on a high building or on a mountain. In the transmitting station, this signal is received, the digital info is decoded and transformed back into baseband.

THE TRANSMITTING STATION
The baseband is then routed to the transmitter, where it is modulated (ie added) onto an FM high frequency carrier. FM stands for frequency modulation, which means that the FM frequency of say, 95.6MHz, is changing slightly all the time, so one second it will be 95.5998, then it will be 95.6005, and so on. What 95.6MHz means is that the signal is being switched on and off and on again 95.6 million times every second. This high frequency carrier signal is amplified by the transmitter equipment, and then the signal is sent up a cable to the top of the transmitter mast, at the top of which are antennas that convert this electrical signal to an electromagnetic signal -  one that is capable of travelling through air.

TRAVELLING THROUGH THIN AIR
The transmitted signal is able to do this because it consists of two fields: an electric one and a magnetic one. When a electric field collapses, it produces a magnetic field, and when a magnetic field collapses, it produces an electric field. So the two fields work like an inchworm, pushing against each other to move forward through thin air.

THE HOPS
Often this signal travelling through the air is received by a more distant transmitting station, where the signal is taken back down to baseband, and then remodulated onto a different frequency and once again transmitted. This is to achieve a greater area of coverage for a particular radio station.

YOUR DEMODULATOR IS YOUR RADIO
Once this electromagnetic signal reaches your radio aerial, the electric part of the signal is extracted, and this is demodulated by your radio. What this means is that the high frequency signal is separated from the baseband signal, and then this baseband signal is again separated into it's various parts, which are stereo sound, RDS (which gives the name of the station on your radio's display) traffic report info, and NICAM, which has the capability of giving you CD quality sound or dual language tracks.

No wonder it's been said "Any sufficiently advanced technology is indistinguishable from magic!"
Getting The Most Out Of Your
Rechargeable Batteries
THEY COST A LOT BUT SAVE YOU A BUNDLE

Rechargeable batteries are used in cameras,  remote controls, torches, etc, etc. and although they are quite an expensive outlay together with a suitable charger, they will nevertheless save you a bundle of cash because they can be used 30 to 100 times over, depending on the brand. If you compare the cost of 100 penlight batteries with the cost of 1 rechargeable battery, you will start to see the savings. They come in various sizes: penlight (AA and AAA), torch batteries (A) , square 9V types and others as well.

AN EXAMPLE OF SAVINGS

Usually a set of 4 rechargeable penlight batteries (size AA) with an included charger, will cost about 10 times what a pack of 4 non-rechargeable AA batteries cost.
Non Rechargeables x 4           = $1.80            After replacing the batteries 50 times:  $90
Rechargeables x 4 + charger =  $18               After replacing the batteries 50 times  $18   (plus about $2 electricity costs)
So you would save at least $70 over the lifetime of just 4 rechargeables.

CAN YOU USE RECHARGEABLE BATTERIES IN ANY DEVICE THAT TAKES BATTERIES?

Yes. They will work fine in any device that they fit into correctly.

WHAT DOES NiCd AND NiMH MEAN?

NiCD stands for Nickle Cadmium and is an older technology. NiMH stands for Nickle Metal Hydride and is a newer technology with a number of benefits.
  • It can be recharged more often.
  • It does not suffer from the "memory effect" so it can be recharged when it is only slightly "used" or discharged with no ill effect. The NiCD type like to be fully discharged before being recharged.
  • It can hold more charge so it will last longer before needing a recharge.
These batteries are rated in mAh, or milli amp hours, usually printed on the side of the battery. eg: 2600mAh. This is the amount of charge they can hold. A 2600mAh battery will keep your device going for longer than a 1700mAh battery.

HOW LONG WILL A RECHARGEABLE BATTERY LAST?

Some of the lower quality brands will allow you to recharge them 20 or 30 times, while quality brands will allow 100 or more recharges before the battery starts to underperform. (Some boast of 1000 recharges; but take this with a pinch of cynicism!) This normally means a year to 4 years before you have to replace the batteries with new ones.
Tried and tested types that perform OK: UniRoss Hybrio, Eveready Recharge.

HOW LONG CAN THESE BATTERIES BE STORED BEFORE USE?

The new NiMH batteries now have a technology called low discharge which allows the batteries to be stored on the shelf (or in your camera bag) for long periods. In a year they will only lose 15% of their charge. Older types of NiMH batteries have to be recharged every few months if left on the shelf.

ARE THESE BATTERIES ENVIROMENTALLY FRIENDLY?

They are mercury free but still need to be recycled. But they are definitely more enviromentally friendly purely because there are less of them to dispose of: in the example above: 4 as opposed to 400 of the non-rechargeables for the same amount of use.

So, make the switch to rechargeables and save yourself some cash and a lot of trips to the store!
     ON THIS PAGE..

   Where to Put a TV
         
<--
   Are Cellphones dangerous
        
Cellphone usage worldwide numbers in the billions. 
        If there is a possibility of injury from these devices,
        then a lot of people will be affected....    

   How a radio Program gets from the Studio DJ
   to your Radio
        
Listening to music on the radio is as normal as
        eating breakfast or combing your hair. It's an integral
        part of most people's day. But if you stop a moment
        and think about it, it is a bit of a miracle how music
        can come through the air.. 

   Getting the Most out of your Rechargeable Batteries
        
THEY COST A LOT BUT SAVE YOU A BUNDLE
        Rechargeable batteries are used in cameras,  remote controls,
        torches, etc, etc. and although they are quite an expensive outlay
Survey Sampling
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