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Solar panel payback period

I refer to the Mailbag item in your August 2002 issue "Are photovoltaic cells really green?" from a Glenn Mayall. Your correspondent once again repeats a myth, attributed to the Reagan era in the USA, namely that solar panels never generate enough energy to make up for that expended in their manufacture. There was a very detailed article on this in "Home Power" magazine January 2001. It is well worth reading both the article and some of the references.

Please, the time has come for you to take a stand and dispel this myth rather than repeat it in your magazine. Check the following article at

Ross Dannecker,
Rockhampton, Qld.

Project suggestion - a silent PC

I have a suggestion for a project: a silent personal computer, preferably in a small case. Even making the power supply fan-less would make a huge difference.

Don't you think it is about time PCs were like the rest of our home entertainment appliances, such as the VCR, DVD and hifi amplifiers, all quiet!

Peter Humphreys,
via email.

Comment: we like your idea but we don't see it happening anytime soon. These days even laptops have fans.

Service history for appliances is desirable

I refer to the note in SILICON CHIP January 2002, page 92, entitled "How to stop rust on screws". This reminded me of standard Service Radio & Radar gear which had red shellac anti-vibration sealer applied to screws etc. This is useful if a service or modification is carried out a different colour may be used to reseal, thus showing a "modification".

I used such method to seal screws in spectacle frames. The colour was easily visible - ensuring sealing had been done, unlike clear varnish which is hard to see.

Secondy, reading the "Serviceman's Log", surely it would be considerate for "repairers & technicians" to put a plate or "log" into the bowels of the equipment giving a precis of service/modification history. This is not new as watch and clock makers years ago recorded service by enscribing in the case of the object.

Finally, service records should record all tests performed with result, whether normal or abnormal. Memory is not a suitable repository of information.

John Ernest,
via email

Electrical wiring regulations in Queensland

I followed with some interest the debate last year regarding the introduction of new laws regarding who could work on mains powered equipment, particular in Queensland.

What has happened to these laws? Have they come into effect? If so does this mean only electricians can do upgrades to computers eg memory, hard disks etc?

Frank Krista
Gordon Park, Qld.

Comment: As noted in the editorial in our June 2002 issue, Queensland carried out a review of regulations and have maintained the status quo, ie, it is illegal for anyone to work on mains-powered equipment unless they have, at least, a restricted licence. Unfortunately, while we made a big effort to change this, there is just not enough interest from our readers or any other bodies (eg, electrical engineers) to make the politicians sit up and take notice. In this country, apparently Apathy does rule!

What's wrong with Basslink?

What on earth is your correspondent Keith Anderson, in his letter entitled "Basslink should be done properly" (August 2002), on about?

He claims Basslink is being done badly, why? He does not say.

The proposed technology for Basslink is conventional state of the art. It is not the only choice but it is a perfectly reasonable and defensible choice.

If Keith Anderson has a valid point about Basslink why doesn't he make it?

Graham Shepherd,
New Town, Tas.

Huge Santa Display panel
Click for larger image

Here are the specs for the Santa Display (SILICON CHIP, November 2000) we made when we found ourselves with a couple of weeks to spare.

Four long days to make and paint, nine hours and one carton to drill the first 1254 holes and the slight chamfer to every hole at its face (looks better), seven 10-hour days to wire using 700 metres of cable and tinned wire. The panel was 3.6 x 1.8 metres. All this is still only driven with the original PC board and one transformer, which still only got warm. Cost excluding the LED stars was $710.00.

We first decided on stars after the rest was done and working, as the background looked a bit bare and with blue and white LEDs costing around $5 a throw, four should have done it but my better half chose the position from the front as I drilled from the back - that's the four white LEDs near Rudolph. That looked too symmetrical so I decided to buy 8 more, 4 white and 4 blue. I could only get 3mm blue at the time (a few bucks cheaper but just as bright as 5mm).

I have saved a few dollars towards this coming year's project. At this stage it looks like I will be using 200 blue LEDs and two of your "flickering flame" PC boards to make an 8-pointed star 2.2 metres high and 1.2 metres across that will twinkle way up high on the roof.

Dallas Redding,
via email.

Critical components hard to get

On quite a few occasions I am keen to construct one of the projects detailed in your magazine but am frustrated by the time taken in sourcing one or two critical components. A case in point is the PC IR Transceiver published in the December 2001 issue. The critical component the SMT transceiver itself described as TFDS4500 by Vishay Telefunken.

I presume this is the Manufacturer (German?). Some direction in sourcing this component within Australia would be appreciated. RS stock a similar device with a different pinout while Farnell don't seem to carry anything in this line at all. Would appreciate any help.

Ross Metcalf,
via email.

Comment: We often have this component sourcing dilemma and it is usually because the component concerned is not available in small quantities from the local distributor or often not available at all from the local people because they just cannot be bothered. The project is available as a kit from Jaycar, Dick Smith Electronics and Altronics. The TFDS4500 itself is available from Farnell, cat 315-2686.

RDS in Australia

After owning a home stereo and car stereo with RDS (Radio Data System) capability I started to wonder why only Triple J was transmitting the RDS information, so I decided to do some research.

After talking to a number of broadcasters I found out that the main reason was that they believed there weren't enough RDS receivers out there. I checked out a few places that sell both car and home stereos, and found that not every second stereo sold had RDS, but still quiet a few did. Many manufactures don't bring there RDS models in to Australia because not enough stations are broadcasting RDS.

So it's sort of a stalemate between broadcasters and stereo receiver manufacturers. It would cost an outlay of less than $3000 for a broadcaster to transmit RDS, and for that their name would be advertised on a lot of people's radios.

In order to gather information on the numbers of RDS receivers, to show broadcasters that it would be worthwhile transmitting the RDS signal, I decided to set up a web page. If you would like to see more broadcasters use RDS, please add your RDS receiver to my page as well as any other stations you know which are transmitting RDS. or email:

Gary Sutcliffe
Brisbane, QLD

Amateur radio articles wanted

What a wonderful opportunity you now have with the demise of Electronics Australia and Radio Mag. It would be a pity to waste such an opportunity, to incorporate the diversity of subjects that these two magazines offered, in SILICON CHIP.

I occasionally purchase SILICON CHIP from our local newsagent but find there are limited articles that suit my interest, with the exception of Vintage Radio.

If you could incorporate articles on Short Wave and Broadcasting Band DX-ing, Amateur Radio, also possibly offer limited free advertising, I am sure you would increase your sales volume no end.

Other topics I am sure would be of interest to the vast majority of your audience would be articles on amateur radio, such as antenna tuners, VSWR meter, RFDS frequencies, aerodrome NDB frequencies and locations, new marine frequencies and locations of marine HF stations, antenna topics and so on.

I respect SILICON CHIP for what it offers, however, I am positive if you offered these subjects, or at least undertake a feasibility study on same you would be very pleasantly surprised.

G. J. Wilson,
Mt. Seymour, Tas.

Comment: While we appreciate that you would enjoy articles on Shortwave, DX-ing and the other topics, we have had little indication of reader interest in these subjects in the past. Are other readers keen to see these sorts of articles?

Cordless phones link for modems

Is it possible to adapt a cordless phone to access the internet over a reasonable distance, say 100 to 150 metres and at say reasonable speed, if not at the usual 56k.

IBM did have some interface with some clever electronics but ceased manufacture in 1998, it was called 'The IBM Cordless Computer Connection".

It would make a nice project, to circumvent the usual umbilical cord we have to live with, and to save the expense of mobile phone gizmos.

Bill Mulders,
via email.

Comment: This is a great project idea but we would have to standardise on a particular cordless phone for any design work.

In appreciation of the Airzone 500

The July article on the "Airzone 500 series" gave me many a wry smile. I had one of these once in 1954. I picked it up off the tip at Willoughby; amazing to recall what was thrown out in those days. However, the series entered my life again round 1980. A friend's parents were given such a set (mantel identical with the one shown on the photos) as a wedding present. It had been stored for many years in their linen cupboard until they gave it to their son, a friend of mine.

It eventually "carked" it in 1980. He asked me to look at it for him and I found the mains transformer was burnt out. Even then, the prospect of securing a replacement was daunting and he rather baulked at having it rewound due to the cost. I told him I'd keep my eye open for one and when I was visiting a friend in Newcastle, asked him if he knew of any "junk shops" where such things might turn up. He mentioned one place on the outskirts so I drove and asked the proprietor. "No", he couldn't assist, but he thought that a chap at Charlestown probably could and gave me the address.

I called in there on my way back to Sydney. The house was a fairly small fibro dwelling, but was almost hidden from view by a mountain of rusted out whitegoods.

I knocked on the door and got no answer. There was pathway down the yard and I could see a shed at the rear with the door ajar. So thinking the owner might be fiddling in his shed, I ventured down and knocked on the shed door. No answer. I peered round the door and as my eyes adjusted to the gloom, I saw something which produced a reaction of mixed shock, amazement and joy.

There before my eyes, stacked floor to ceiling were dozens of radios from the 1920s and early 30s. It was an absolute "Aladdin's cave" of old radios.

I must say that my immediate reaction was promptly followed by a mixture of guilt, occasioned by envy and I thought it best to beat a retreat before the owner turned up in case he got the wrong idea. I turned to go and as I went to close the door to I found it wouldn't shut.

I glanced down to see what was blocking it and to my sheer amazement, there was a power transformer complete with tagstrip, covered in dirt and dust. I picked it up and rubbing the dust off the tagstrip, I saw from the voltages and ratings that it was exactly what I was looking for. What should I do?

I debated waiting for the owner, then telling myself that if he used a transformer where he could use half a house brick, he didn't see the transformer of any value. So I decided to "buy" it.

I took it out to the car where I wrote a note explaining what I'd done and stuck a $5 bill in it and put it under the front door. I left feeling rather guilty. I cleaned it up, checked the voltages and found it OK, removed the tagstrip, installed "flying" leads and mounted it on the Airzone.

About six weeks later I was in Newcastle again and plucking up the courage to visit the house at Charlestown, I drove down the street looking for the house with the white-goods.

I couldn't find the house matching that description but judging from its approximate position, the bare earth and the fresh coat of paint on the house, I pulled up outside the place. There were two young fellows leaning of the bonnet of a "souped-up" Cortina, tinkering with the innards.

I approached them and saying I thought I had the house right, describing my earlier visit, was informed that "the old bloke" had died. "What happened to all the old radio stuff down in the back shed?" I asked. "All that old junk went to the tip mate," I was informed. I left in sorrow.

Richard Lockhart,
Artarmon NSW.

Comment: we have published this rather long letter as a cautionary tale. If you have a big collection of "valuable" stuff, don't let it be disposed of in this way after your demise. Sort it, catalog it, sell it or give it away but don't let it be sent to the tip!

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