Mobile phone health hazard may be long-term

I have read with interest your editorial in the June 2006 issue of SILICON CHIP, dealing with possible health hazards associated with the use of mobile phones. I strongly agree with your comments and would like to suggest that perhaps the magazine should take the matter much further.

I worked for many years on environmental problems in the nickel industry and in particular was concerned with the carcinogenic effects produced by some particular types of nickel fumes in the atmosphere. This material was the cause of many cases of lung cancer in the industry in several countries around the world and the overall story was very similar to the situation with cigarette smoke and asbestos.

Radio frequency radiation has also been recognised as the possible cause of similar cancer problems, with high voltage power lines and radar transmitters being among the prime suspects. In this case, the main variables are the frequency and the intensity of the electromagnetic field. The mobile phone is, of course, only a low-powered device but the inverse-square law and the fact that the phone is usually located only a few centimetres away from the brain suggests that it may possibly pose a significant hazard.

I think that one of the most important aspects of the three separate cases mentioned above, which involved dusts, was that the health problems usually only appeared 20 to 30 years after the initial exposure to the hazard. If the mobile phone does in fact present a similar hazard, this fact is therefore not likely to become apparent for perhaps another 10 to 20 years or so.

In the meantime, it appears to me that it would be prudent to conduct a strong publicity campaign to minimise the use of these phones as far as possible. It is only if no major effect becomes apparent in the next 20 years that we can say that no real hazard exists. The fact that no health problems have yet appeared does not prove that none exists. In the meantime, it is only the phone companies who have anything to lose if we play it smart and reduce our own health risk by minimising the use of these instruments as far as is practical.

Bert Hollebon,
Cloverdale, WA.

Winch controller could be simplified The winch controller published in the January 2006 Circuit Notebook is indeed a credit worthy design but the inputs to a PICAXE chip are Schmitt triggers. Therefore all of the circuitry that de-glitches the inputs (IC2, IC3, IC5 and all associated components) is not needed. The debounce function of this extra circuitry can be done in software. Removing all these components will make the unit much cheaper and a lot smaller. Jeff Monegal, Via email. Comment: you’re quite correct but both design concepts (ie, the hard-ware and the software approach to switch debouncing) are valid. The way we see it, Circuit Notebook is not necessarily about the cheapest, simplest way to achieve a result.

Australian TV tests
at Brisbane

I thoroughly enjoyed the article in the June 2006 issue but you didn’t mention that the tests at the Old Mill in Brisbane continued up to the outbreak of WW2 when they had reached 240 lines. There was also a demonstration in a house in Brighton (Vic) in 1949, as was reported in "Radio and Hobbies" magazine. Also, when Alfred Zworykin visited Melbourne in 1951/2, he demonstrated his latest invention, the Vidicon camera.

It’s also worth noting that in 1960 it was realised that some of the original 10 channels planned would not be available in time to start the country stations. This led to a new 13-channel plan. What is now 5A was originally 5, with 4 just below. Channel 0 did not exist in the 10-channel plan and 1, 2 and 3 stayed below the FM band. 10 was moved down slightly so 11 could be added. 1 and 2 moved up to allow 0 and 3 joined 4 and 5 in the FM band. This was detailed in "Radio Television and Hobbies" in 1960 (August, I think).

The FM band was occupied from 1949 to 1960 by FM tests in Brisbane, Sydney, Melbourne and Adelaide.

Wenlock Burton, VK3YWB,
Darley, Vic.

June 2006 cover credits

I have just picked up the June 2006 issue from my local newsagent. As usual, it is an interesting read, particularly the history of television in Australia.

Your cover photograph shows a TV set and lounge chair which is very reminiscent of that era when TV first came into our homes. However, I thought it was customary for magazines to include a short synopsis of the front cover photograph or at least an acknowledgment or identification of any people included therein.

I cannot find any such mention in the magazine of the very beautiful lady on your June cover and I think she deserves that recognition. The photograph with the model is just so ‘spot on’ for authenticity so I think we readers should know who she is and somehow "Ms June" just doesn’t seem fitting.

Bob Howie,
via email.

Comment: glad you liked the issue and the cover. The lady is Julie, daughter of Kevin Poulter, who wrote the TV series. Julie has a keen interest in 50s and 60s decor, fashions and memorabilia.

It occurred to us that you might want to know other details as well, since they are all authentic to the period, including the house itself. The aluminium venetian blinds were probably made by Luxaflex while the polished floor is Australian cypress pine (very popular at that time). The AWA Deep Image TV is in working condition although the Channel 9 TV pattern was dropped in electronically by Kevin Poulter (who also took the photo).

Other props include the TV chair with wool boucle cushions (probably made by Parker Furniture) and the anodised aluminium TV lamp. Julie Poulter is wearing a 1950s cotton halter dress with atomic starburst print, 1950s "Curvees" suede high heels and 1950s "Weiss" Lucite and rhinestone jewellery.

Early TV experiments in Australia

Thanks for your article on television in Australia, in the June 2006 issue but the Australian connection is much more important than you portrayed. In writing this I am working from memory so some details may be wrong but I believe it was a Mr Saunders from Ballarat who used the telegraph lines to send the signals and modulated the light of a kerosene lamp with a Kerr cell to show the 1896 or 1898 Melbourne Cup in Ballarat.

He realised that the telegraph system did not have enough bandwidth and he had no amplifiers so he stopped development. The Melbourne museum some years ago had his apparatus set up for display. Unfortunately, his work has generally been forgotten.

Rod Cripps,
Parkdale, Vic.

Acid-free resin flux paste I saw the request for acid-free flux paste in the Ask SILICON CHIP pages of the April 2006 issue. There is a very easy way to make your own resin flux. Go to a music store and buy a block of resin (it is used on bow strings). Crush it up very finely and mix it with a small amount of methylated spirits to make a paste. Spread it on the clean copper, solder and you don’t have to clean it up after. Arthur Prince, Comment: thanks Arthur. That is a good way to make a mild solder flux. However, an analysis is likely to reveal that it is not completely acid free. It will have a number of organic acids related to the tree species from which it originated.

Fire sensor for sprinkler system

I am writing with regard to the reader’s request for a fire sensor in the "Ask SILICON CHIP" pages of the May 2006 issue. Several years ago, I worked for an organisation (Cerberus) in a technical support role with respect to fire detection systems. In their range of products was a flame detector but the price today would be prohibitive for the "private" user (around $700 per unit) wanting to provide protection for an unoccupied property. As a guide, the device was capable of detecting a methyl alcohol flame (little to no visible signs) in a tea-candle container at about five metres.

The general philosophy of any fire detection system is that it only has to work long enough for the occupants to evacuate the premises and that it should be "out of sight, out of mind" until it is required. With respect to unattended systems and approaching bushfires, the smoke density (obscuration) will be likely to be at alarm levels at a significant time before the fire front arrives and temperatures will be at elevated levels because of radiant heat from the fire, making ordinary smoke type and heat type detectors ineffective. Factors such as environmental temperature, wind speed and direction, humidity, fuel load and neighbouring vegetation all affect the speed and intensity of the fire front.

Pre-wetting is a good idea in that it interrupts the fire triangle (fuel, heat and oxygen) by reducing heat through evaporation but delaying the wetting down reduces its effectiveness, and starting it too early just wastes water. If one assumes that there is a bushfire, then there are no guarantees regarding reliability of electricity supply or water supply, meaning that alternative supplies (pools and tanks) must be utilised and mechanical pumps used to pressurise the spray system.

The amount of R&D that had gone into the aforementioned flame detector was significant – especially with regard to flame flicker frequencies and other flame behaviours. Without being negative, it might be a little optimistic for someone to design (and get right first time) a fire-front detector that can break out the fire pump, put the foot in the pool/tank/dam, prime the pump, divert the pre-wet system and mop up without human intervention.

All of the above points pretty pessimistically to the fact that a human must be at "ground zero" with enough intelligence to make certain decisions about the situation.

Another way to consider it might be like this: if you can’t afford to lose the asset, you can’t afford to be uninsured. Furthermore, if it really is valuable, why is it remote and unattended?

Mike Frede,
Albury, NSW.

Nuclear fusion will be
worth the wait

As you probably know, the world’s first nuclear fusion plant is to be built at Cadarache in Southern France at a cost of 10 billion euros. It has been estimated that if this process can be successfully harnessed, then there is enough fuel available to supply the planet’s energy needs for at least 1000 years. It would also go a long way toward solving the effects of global warming created by the continued burning of fossil fuels.

In a news item in the May issue of IET there is a report of a study into safety with respect to these new generation nuclear power plants and the authors have concluded that a severe environmental impact would be "impossible" and that even the "most severe" accident would not require public evacuation.

Because of the technical difficulties that still have yet to be resolved, this plant is not expected to be commissioned before 2045-50. My hope is that we will see a result well before this. Countries such as New Zealand and Australia should have a watching brief on these developments rather than moving into generating plants using nuclear fission.

John Rogers,
via email.

Comment: there is no certainty that nuclear fusion will ever be safely harnessed for power generation. If it is successful, the world will never have an energy shortage. However, Australia cannot afford to wait for 30 years or more for the possible outcome of nuclear fusion research. It is highly likely that we will have many nuclear fission power plants by that time.