OVER 2 YOU, 151 (14/10/03)

LARGE PRINT KEYBOARD

I am partially sighted and need a large print computer keyboard. Does anyone know if such things are available, or maybe suggest an alternative?

Murray Wren

Yes, they do exist and I cannot recommend too highly a Southampton based company called Keytools who specialise in IT equipment for RSI
and other health problems. The website www.keytools-ergonomics.co.uk

Jane Buswell

The Keyboard Company (UK), http://www.keyboardco.com/ has a wide range of specialist keyboards. I have a sight-impaired patient who is interested in two such keyboards. Both measure 7 x 18.5 inches; the keys are 1-inch square and bright white with large black lettering. The 'arrow' keys are in a separate pad to the right end of the board, well shaped and clearly marked. Supplementary keys are on the right, above the arrow keys in the space normally occupied by the numeric keys.

Dr B. R. G. Hutchinson

The most popular large key keyboards are the BigKeys range, which have 10 varieties (either PS2 or USB) and are compatible with both Macs and PC's. These keyboards are the same size as a standard keyboard but have keytops that are 4 times normal size. To accommodate this they do not have a separate number keyboard or the "F" keys. For more information go to: www.bigkeys.co.uk 

I am pleased that somebody has raised this question and hopefully this will help raise the profile of such equipment, which due to small size of the market often proves to be more expensive. The more people that are aware these devices exist the greater the demand and the better the economies of scale.

Russell Parrott

Murray Wren should visit or contact www.pulsedata.com who market large print keyboards.

Barbara Frost

SPEEDO CALIBRATION

I live in dread of being ‘flashed’ by speed cameras. I do not knowingly exceed the speed limit but I have only my car’s speedometer to rely upon. Reports that speeding tickets could be issued for breaking the speed limit by only a couple of miles an hours prompts me to ask if anyone can suggest a method of checking the accuracy of my car’s speedometer, possibly using my laptop PC and some sort of distance/speed measuring software?

Arthur Kennedy, via email

I use a Global Positioning Satellite (GPS) receiver to accurately monitor my speed and, coupled with the right software and database will alert you to speed cameras as you approach them. It's not a cheap option but if you know
some one who owns a receiver you could borrow it. Further information about GPS receivers and software for alerting to Speed cameras can be found at http://www.pocketgps.co.uk/index.php
Clyde Martindill

There are numbered fingerposts every 100 metres on motorway verges. On a quiet day, drive at a steady 70mph by your speedometer, and have a passenger use a stopwatch to time 2km (20 posts). The average of several runs should be 64 seconds. To find your real speed in mph divide 4473.864 by your time in seconds. My Cavalier used to lie by 10 percent – 77 mph on the speedo was really only 70mph, and so on. I never did get Vauxhall to explain, but suspect the explanation was that they'd fitted low-profile tyres, so the wheels turned more often per mile than the wheels they'd originally used to calibrate their speedos.
Mike Wells, London NW5

With a companion armed with a stopwatch and calculator find a reasonably level stretch of motorway and drive at a steady speedometer reading of, say, 70 mph. Avoid sections with bridges or junctions, which disrupts the regularity of the kilometre marker posts

Take stopwatch readings over one or preferably more kilometres, while the speed is kept steady. Divide 2240 (the number of pounds in a ton - irrelevant, but a useful reminder) by the number of seconds per kilometre. That gives the answer for true speed in mph. For example: 32 seconds per kilometre is a true 70 mph, 28 secs is 80 mph. My Renault Scenic speedo proved to be 7% fast.
Michael Igglesden

Close to where I live, in South London, the local council have installed several lamp post mounted speed indicators that flash up your speed as you pass by. I’m not sure how accurate they are but they consistently indicate that my speedo over reads by around 5%

Gill Davies, via email

The speedometers on most cars will be fairly accurate up to 30mph. Conventional ‘disc’ instruments have a bias which means that as the road speed increases the indicated speed rises faster thus overstating the actual road speed. Higher spec cars have optical disc speedometers which are digital and are much more accurate at all speeds. The accuracy of all speedometers depends on the assumed circumference of the tyres on the driven wheels. If you have changed the wheels or fitted tyres of a different profile or the tyres have worn the speedometer accuracy will be compromised.

If Arthur Kennedy is really concerned to establish the accuracy of his speedometer he could use his rev counter, which is also digital and intrinsically accurate and linear. To make use of the rev counter he will need to measure the distance his vehicle moves during one revolution of the driven wheel(s) and use the relevant gear ratio information to establish a range of useful check marks on the rev counter.

It is possible to measure the driven wheel circumference by placing a plank of wood about 6 feet long alongside a driven wheel and making a contiguous chalk mark on the tyre and the plank at the low point of the wheel.  Push the vehicle forward or backwards until the tyre chalk mark next comes into juxtaposition with the plank and mark the plank at this point. Measure the distance between the two chalk marks on the plank in feet and inches.

Using the gear ratio information from the vehicle specification/handbook work out the number of engine revolutions in, say, 3rd, 4th and 5th speeds for 30, 40 and 70 mph.

For example:

Gear ratios 3rd = 1.28:1, 4th = 0.89:1, 5th = 0.71:1, Final drive = 3.55 :1

Measured wheel circumference = 5ft 9in = 5.75 ft

Wheel revolutions per mile = 1760 C 3 ¸5.75 = 918.26

Engine revs per minute in 3rd gear at 30 mph: 30 ¸ 60 C 918.26  C 3.55 C 1.28  =  2086rpm

Engine revs per minute in 4th gear at 40 mph: 40 ¸ 60 C 918.26  C 3.55 C 0.89  =  1934rpm

Engine revs per minute in 5th gear at 70 mph: 70 ¸ 60 C 918.26  C 3.55 C 0.71  =  2700rpm

It is of course much better to "get the feel" of 30mph and 40 mph than to constantly refer to the speedometer and take one's eyes from the road ahead.

Richard Ball

On most motorways, usually near to a police traffic base, are measured countdown markers, quartered yellow and red discs. These indicate the start, 1/4, 1/2, 3/4 and mile distances. These are used by traffic officers to check the calibration of the speedometers fitted to traffic enforcement cars and motorcycles, for evidential purposes.
Thomas Williams, Windsor

Don't bother. Providing that you have not modified your car, so that wheel size and speedo no longer match, you have nothing to fear, if you obey the limits within reasonable human limits.

Contrary to popular myth, the cameras are there to catch idiots prepared to risk other people’s lives for their own selfish ends.  Drive at 35 mph in a 30 limit and you deserve no sympathy but the people they are after are idiots driving at 40, 50, even 80 miles an hour.

Safe driving is about the right speed at the right time, which may well be below the posted limit, for instance in a busy high street. It is about observation, anticipation and care. Excessive watching of the speedometer will detract from the overall task. Get used to the right speed and you can drive almost without checking.
P.W., via email

CAN YOU HELP?

I recently inherited a beautiful old wooden cased Ferguson television set, made in the early 1960s. It appears to work and the screen lights up, but I cannot get a picture as it uses the obsolete 405-line television system. Is there any way I could connect it to modern video equipment or maybe even a PC, using some sort of converter perhaps?

Daniel Sutter, via email 

I am about to print tickets (10 per A4 card: 5 rows and 2 columns) in MS Word for my local Bowls Club. Can anyone suggest a way of numbering them from 001 to 200, preferably in the bottom right hand corner where there will be a 'Lucky Number'?

Ted Creswell, via email

We hope to scan over 50 years of a quarterly technical journal, totalling some 20,000 pages. We already have an index to the volume numbers and page numbers in Word/Excel format. Can anyone suggest a software package that can link the scans with our existing index, to enable a search and retrieval of a particular page?
Richard Sykes, via email