Compact fluoros do comply
with Australian standards

Graham Lill seems very concerned about the 1mm track spacing on the mains side of the PC board of his disassembled compact fluoro (SILICON CHIP, Jan. 2006, page 7). Having spent six months in a Melbourne Lab testing, for a large part of the time, compact fluoros with very similar PC boards, I can assure Graham that all is well (assuming that the product was bought from a reputable supplier).

The product would have been tested to Australian (Safety) Standards before being allowed for sale. If my memory is correct, AS3100 sets down the testing methods and one of the tests is the clearance between live parts, in this case Active & Neutral. There are other specific safety standards for rigorous testing of this product.

The Active & Neutral would be my least concern as these have a potential difference (PD) of only 230VAC RMS (as per AS3000) whereas the four leads to the tube could have a PD of up to 2500V RMS (VDC + VAC). If I recall correctly, 2.5kV is the limit set by the Standard and I have measured well in excess of this on products provided for testing. These products failed and were returned to the manufacturer for suitable modifications.

For peace of mind, purchase only products tested to Australian Standards – the C tick (EMC Compliance) is a good indication that the product complies.

Mike Abrams, MIEAust,

Capalaba, Qld.

Unmute facility for
portable PA amplifier

In the January 2006 issue, pages 115 & 116, you published a possible solution for an unmute facility for the PortaPal PA system. I had a similar requirement and tackled the problem slightly differently. I mounted a SPDT (centre off) switch on the front panel and connected +12V and Gnd to either end of the switch. For simplicity, I made connections to either side of D3 from the component side of the board. I then connected the common of the switch to the anode of D2, again from the component side.

This now gives me the flexibility to use the device as per the original design (centre off position), permanently suppress the mute so that initial chords of the guitar riff are not lost or alternatively, force the permanent mute. The latter allows signals to be pulled off from the line out and fed to other systems, etc without coming through the speaker.

It only takes about half an hour to modify and I have been using it like this for about six months with no problems.

Mick McCarthy,

via email.

Support for
nuclear power

I was very interested in your editorial (SILICON CHIP, January 2006) to see you suggesting nuclear power for Australia. Except for Sir William McMahon, we would have had a power station at Jervis Bay and probably several more by now.

It’s ideally suited to this country. It’s clean, we have plenty of fuel and being a stable country geologically we can store the small amounts of waste quite easily. I am sure that if the general public understood more about it we would not get the reactions we usually get, as these are based on lack of knowledge and fear of the unknown.

Some years back, the Australian Atomic Energy Commission carried out a study into the "most credible accident" to try to estimate how many deaths and injuries would follow a genuine major failure in an atomic power station. Mean time between failures was taken into account and the study also included conventional power stations as a comparison. The study covered all deaths from the time of producing the fuel to disposing of the waste products.

It soon became apparent that the number of deaths from a nuclear accident was likely to be far less than the number of people killed during the normal production of power by conventional means. If we look back over forty years or so, the number of deaths in the western world from nuclear power or any accidents involving the production of nuclear power is far less than the deaths associated with more conventional power generation.

In time, solar power and other forms of non-polluting power will undoubtedly take over but these technologies have somewhat further to go in their development to become really viable. In the meantime, we could and should use nuclear energy to reduce our greenhouse gas emissions, as our energy needs are only going to grow in years to come.

I probably should declare my interest here – my father was chairman of the AAEC from 1957 to 1972 and led one of the British teams to the US during the war to help the Americans build the two atomic bombs that were dropped on Japan. So I grew up in an atmosphere that was positive about nuclear energy and the benefits it has for us all. I am still positive about the benefits of nuclear power.

Rod Baxter,

via email.

We should develop
fast neutron reactors

I wholeheartedly agree with your editorial suggesting that Australia should build nuclear power stations. It is clear that renewable energy in the form of solar or wind is not going to be close to providing enough power to meet our needs and in order to actually shut down existing coal/oil/gas power stations, nuclear power is the only viable solution.

Further, the December issue of "Scientific American", Smarter Use of Nuclear Waste (http://tinyurl.com/7bp8w), talks about fast neutron reactors. These can extract power from 99% of uranium or plutonium (including non-radioactive uranium and uranium/plutonium waste from existing nuclear reactors and superfluous weapons-grade plutonium), while producing waste that is radioactive for only 300 years (instead of 10,000) and never requiring or producing pure weapons-grade materials.

If Australia was to start importing and storing nuclear waste now, while designing and developing fast-neutron reactors, not only could we earn money from exporters of nuclear waste, we could turn that 10,000-year storage waste into 300-year storage waste while providing power with negligible impact on the environment.

For anyone who is opposed to nuclear power on the grounds of potential disasters, they would do well to remember that all existing power stations pollute the air, leading directly to deaths in nearby populations as well as contributing to global warming.

Australia is in a unique position to both accept nuclear waste and develop fast-neutron reactors.

Peter N. Lewis,

via email.

Distributed power generation
is the answer

I feel compelled to respond to your assertion that we should build nuclear power plants to replace the coal and gas plants dotted about the country. I don’t really have any concerns regarding safety or waste issues, though it is difficult to sort through the misinformation that abounds. No, the problem I have is that nuclear is simply a variation of old technology that is a bit past its "use by" date.

Firstly, central generation is incredibly wasteful; coal-fired power stations generally run at some 35% efficiency. Thus for every 100 units of fuel energy going in, only 35 units of electrical energy come out; 65% is wasted as heat in those huge cooling towers. The waste is inherent any heat engine; nuclear is no exception.

Secondly, the power grid is already groaning under the load and the demand doesn’t look to be decreasing any time soon.

My solution is distributed generation. Technology has progressed to the point where it is possible to efficiently generate your own power in your back yard and sell any excess back to the power company. The grid then needs to deliver less power overall and the "waste" heat generated is easily harnessed to heat water and living areas, and even power air-conditioning and refrigeration rather than dissipating into the atmosphere. Even better is that one would have the option of powering the "backyard utility" with sustainable fuels such as ethanol, edible oils, bio-diesel, wood, etc and produce zero net CO2.

It is not a good solution for everyone or everywhere and like any form of alternative energy, it needs careful analysis to match the application with the hardware.

Nenad Stojadinovic,

via email.

Power can come
from hot rocks

So you advocate nuclear power generation. There is a far cheaper and extremely environmentally friendly solution right under your feet – "hot rocks". The only major and different expense for this technology is for the $1,000,000 per kilometre (using current proven techniques) to drill the down to the required depth. Now this depth may seem excessive at up to 12km but it can be done. And with the newer techniques of microwave cracking of the rocks and even laser cutting (ex-Boeing), it will be even cheaper in the near future.

Of course, insulated pipes are then needed to bring that very hot water back to the surface but again the technology is easily available. When you have that water at the surface it is expanded into steam to drive a standard steam turbine to generate electricity. No towers are needed as the output hot water is simply sent back underground.

South Australia is already investing money into this technology, at Coopers Creek.

Bruce Withey,

Grafton, NSW.

BPL trials held
in isolation

I have been reading the Mailbag feedback on BPL (SILICON CHIP, January & February 2006) with interest. While I’m not qualified to comment in a technical way, I do have many years of experience to draw on.

There’s one factor that’s been overlooked so far in the trials of BPL currently underway in a Hobart suburb. That factor is isolation. The suburb where the trials are currently underway is called Tolmans Hill, a new suburb of just a few dozen houses at most.

Being surrounded by trees, Tolmans Hill is at least 1km from the nearest buildings in all directions. It has a very large hill in between to screen other Hobart areas from it.

If I had to pick the perfect place to trial BPL and I wanted to claim no interference to others, Tolmans Hill would be it.

So any data regarding interference from BPL in these trials should be viewed with caution because there are not many people living close enough to have any real problems with it.

Before any decision is made regarding the introduction of BPL, trials should be undertaken in other Australian inner city areas. I think this way we will quickly find out if there’s a problem from interference, or not.

Jack Gill,

via email.

Some Plasma TVs
only have 480 vertical pixels

I agree with your sentiments that (some) "home theatre systems are not worth watching" (Publisher’s Letter, SILICON CHIP, February 2006) but for a different reason.

Some systems being sold into the Australian market are actually designed for the lower resolution NTSC system used primarily in North America and Japan. PAL (the Australian TV standard) has 576 visible scanning lines (vertically) whereas NTSC has only 480 visible lines. Displays designed for the NTSC market therefore usually only have a vertical resolution of 480 pixels. Displaying a PAL signal on a lower resolution panel (one designed for the NTSC market) results in a loss of approximately 17% of resolution in the vertical direction.

Last year a nearby store had a plasma TV on display which had this exact problem. The native resolution of the panel was 852 x 480, which is incapable of fully displaying PAL’s 576 lines (any PAL signal would be interpolated down to 480 lines). And yet there was an advertising sign on the unit which said "higher resolution than standard television".

This is blatantly untrue. It is true that the horizontal resolution of this set was higher than the 720 pixels provided by digital SD PAL broadcasts, however you can’t invent resolution and certainly does not make up for the loss of resolution in the vertical direction.

Imagine my horror when I realised that the Epson projector reviewed in the February issue exhibits this same problem. The native resolution of this projector is only 854 x 480; fine in the horizontal direction but terrible in the vertical direction.

Andrew Woods,

Curtin University of Technology,

Perth, WA.

Seismograph plots of a recent earthquake I have attached two recordings of a Magnitude 7.7 earthquake from the Banda Sea in Indonesia. The quake occurred on Saturday morning (January 27th, UTC). One recording was made with the "Picaxe" seismograph detector sending data to the "StampPlot" graphing program, exactly as in the SILICON CHIP article in September 2005. The second recording was using a magnetic coil/magnet detector feeding a Dataq DI194 RS data analog to digital converter (an option suggested in the article) and displayed using a program called AmaSeis. The seismographs were identical to the article design. AmaSeis presents the detected data so that it looks like the traditional seismograph helical recorders. Each line is one hour and the bottom line is the current hour. The advantage of this is that you can see the last 20+ hours on the one screen. Dave Dobeson, via email.

Lithium polymer batteries must be treated with care It was nice to see the electric flight article in the February 2006 issue. Unfortunately, your information and advice on LiPO (lithium polymer) batteries is incorrect and could result in your readers destroying their cells. First of all, in the figure on page 11 you show an 1800mAh 3S (three series cell) pack but you have nominated the voltage as 11.4V. This is incorrect as this is an 11.1V (12.6V fully charged) pack. LiPO cells have a nominal cell voltage of 3.7V, with a fully charged voltage of 4.2V. Then on page 15, in the second last paragraph, you state that modern electronic speed controllers have a built-in LiPO low voltage cutout of 2.4V per cell. If this was the case, the cells would already have been permanently damaged, as the widely accepted level is 3.0V per cell. This is from manufacturers’ and distributors’ information. On page 19, you repeat this incorrect information on your warning page. You also state that you should never exceed a discharge current of 9C, which may be correct for one particular manufacturer’s battery but is by no means correct for many modern LiPOs which are capable of 12C or more (according to their technical data). Contrary to the (now old) views that these cells are about as safe as a bottle of nitroglycerine, modern cells in general are quite safe given a reasonable level of respect. Yes, there are certain safety rules which will make usage even safer but the same can be said of high energy Nicad or NiMH cells. Charging these cells using very simple home-made chargers is quite feasible and is very popular within the RC community. For an excellent source of information on these and many other electric flight resources I would recommend the www.rcgroups.com free forums. Ingmar Meins, Griffith, NSW. Bob Young comments: I am afraid Ingmar is suffering a severe case of message sent does not equal message received. (1) On page 15 I said that the ESC has a low voltage cutout to prevent the batteries falling below 2.4V per cell (the destruction point of LiPOs). I did not say the ESC was set to cut off at 2.4V – it just means that the cut-off prevented the batteries from ever reaching the point at which the batteries will destroy themselves. (Some sources quote 2.5V per cell as the destruction point, by the way). (2) On page 19 I again quoted the accepted destruction voltage, not the safety cut-off point. At no point in that article did I ever quote a safety cut-off point. I am only ever talking of the point at which the batteries will be ruined and pointing out that the batteries must never reach that point. A safety cut-off is not going to stop self-discharge destroying a battery. (3) The figure of 11.4V is incorrect and for this I apologise – a bit of dyslexic transposition between 7.4V and 11.1V, the figures quoted on my LiPO charger I am afraid. (4) 9C was the commonly quoted figure in the reading that I did on these cells. Some modern cells I have found out since are quoted as low as 7C. Nobody is going to get into trouble using a battery at 9C even if it is a 12C battery. I prefer to be conservative. There have been some very nasty accidents recently in Australia with these batteries and they must be treated with great care. I stand by that.