Queensland always has been a closed shop

I have an amusing story about getting restricted electrical licence recognition in Queensland many years ago when I worked for Telecom (now Telstra). The inspector came to our site to see whether we had sufficient training to allow us to fit power cords to the battery chargers we were installing.

We had set out a wide range of equipment that illustrated that we manufactured, installed and repaired very high voltage, high power and high current equipment at both power and radio frequencies that far exceeded what the restricted ticket covered. I pointed out that the broadcast transmitters had high voltage, high current power wiring and mains voltage control circuits. I even showed the inspector a spectrum analyser we were repairing to give an idea of the technical level of the people in the workshop.

Needless to say, I was taken back a bit when he subsequently said "Yes I see all that but do you get taught Ohm’s Law?" I explained that we did and that a technician had at least five years of theory and practical training. Knowing that I had demonstrated that we more than covered all aspects of the restricted ticket, I was absolutely gobsmacked when he finally said, with a straight face, "In all honesty I couldn’t recommend that you people be permitted to fit power cords."

A safety issue or a desire to keep a closed shop? I’ll leave the decision to you.

Mark Little, via email.

WIA needs to take a business approach

The WIA has a great opportunity in the near future to take over functions from the ACA and manage them in the interests of radio amateurs. Examinations are currently being investigated for devolution and there has been talk of devolving licensing at some later date.

If the WIA is to carry out these functions then good organisation and sound management will be required. It is therefore unfortunate that we have recent examples in both Queensland and Victoria of decisions to cease running their WIA divisions as businesses with paid staff. In both cases the decision was accompanied by a substantial fall in members funds.

It would seem the directors involved were anticipating declining rather than improving business, justifying their decisions to accept the costs required to change direction.

That this has occurred should in no way affect the perception of what can be achieved nationally with a bigger market and a specific business plan identifying the opportunities. The WIA can only carry out devolved work from the ACA on a national basis.

Martin Luther, Willaston, SA.

A more detailed paper is available on the ARA website at:

www.amateurradio.org.au

LP Doctor works well on 78 RPM records

I wrote to you some 18 months ago with regard to designing a device to remove clicks and pops from records. Some time later you wrote back to me advising you had designed the LP Doctor which was eventually published in the January 2001 issue. Thank you very much for what obviously has been a great deal of work for you and your staff.

I have recently constructed the kit from Dick Smith Electronics and bench-tested it, and I am pleased to say the device does as you claim. Further to this, it provides some good results on 78 RPM records which were my main concern. I actually got a battered old 78 and scratched it quite badly with a screwdriver just to prove the point.

The LP Doctor is valuable to my cause with regard to presenting nostalgia programs on community radio: "Memories of Yesterday" on Plenty Valley FM – Melbourne 88.6MHz.

I have a further request: is there a way in which I can feed the LP Doctor input at line level by bypassing the phono input?

Ken Jeffrey, Epping, Vic.

Comment: you can feed a line level signal directly into the output level control VR1, in both channels. This will require some switching, so that the output of the preamplifier does not load your line level signal.

Digital amplifier article appreciated

The article on the digital amplifiers in the July 2001 issue was very interesting and the web contacts for further reading are very useful. I like the way you have cut through the hype, blurb and marketing to explain the basics. I note that a review in "Australian Hi-Fi" of that Sharp $25,000 unit made mention of an impedance switch. If the amplifiers are reliant on a low-pass filter, surely the impedance of the speaker would affect its operation – especially as it varies all over the place (wildly with some speakers).

How a digital amplifier would behave around the crossover frequencies and bass resonance peaks would be an interesting thing to find out. Perhaps they will only be suitable for mass market audio gear where the speakers are sold with the amplifier and the responses/filter characteristics can be tailored to the drivers used. All in all, an interesting article.

John Richardson, via email.

Comment: you could be right about digital amplifiers being tailored to suit certain speakers. Maybe they will never become the amplifier of choice for true hifi enthusiasts.

EMC standards not being policed

Several years ago the Spectrum Management Agency (SMA), now the Australian Communications Authority (ACA), promulgated a number of Electromagnetic Compatibility (EMC) Standards and Electromagnetic Immunity Standards (EMI) for electrical/electronic devices.

Some people at the top of that organisation believed that these new standards would be embraced by the manufacturers of devices likely to cause interference or likely to be interfered with. With this naive belief in mind, I suggest they believed that experienced interference officers were no longer needed and were made redundant.

Did the manufacturers do as expected? Some Australian manufacturers did and still do. Overseas imports? Well, people see the CE sticker on equipment coming into Australia and probably believe the equipment meets some standard.

But just because there is a label on a device doesn’t mean it meets the standard or ever has met the standard. Paper CE stickers cost about a dollar per thousand!

I have bought equipment (mostly Chinese) that has the CE sticker applied and they are some of the worst generators of radio interference I have ever had the misfortune to own; so bad that the local AM broadcast station (20km away) can just be heard through the interference.

My wife and I bought an electronically controlled automatic washing machine that was supposed to meet the interference standards. It was just as noisy as some of the imported junk that had the CE compliance stickers attached to them. I complained and around two years later I had an interference suppressed control panel fitted and now I can hear the radio stations.

What did this tell me? It told me that the washing machine probably was tested with the suppressed board fitted but the production line model had the unsuppressed board fitted.

Computers – now there is a story. They are required to comply with the EMI and EMC standards since January 1999. The ones I have seen create more interference and are more likely to suffer data corruption from mains-borne interference than earlier computers. I have not been able to find any seller willing to state that their equipment meets the EMI and EMC standards.

There are multitudinous devices causing interference out there and the ACA seems uninterested in policing the standards that they have put in place. They can cry that they don’t have the people to do this – well they did, but they got rid of most of their experienced technical officers.

Are we going to let Australia once again be the dumping ground for inferior equipment that could never meet an EMI or EMC standard? Overseas countries and many of our greedy importers are quite happy to sell the cheap and nasty stuff to us, claiming when challenged that they didn’t know there was anything wrong with the equipment that they sell. Pull the other leg!

Most cars these days are relatively quiet electrically but some Diesel-engined vehicles generate quite severe radio interference – not what you would expect. Don’t expect any help from the vehicle manufacturers either. I wonder about interference standards for vehicles. Does anyone know what standards apply to them?

Rodney Champness, Mooroopna Vic.

Electricians’ closed shop to end

I have been a SILICON CHIP reader for years and think your magazine is tops. I have had a bit of a scare recently reading your suggestion that the "closed shop" on home electrical work should be opened. I am very concerned as to what level you are suggesting that people should be allowed to perform their own work on mains appliances and household wiring.

I am an electrician by trade and I have recently finished my electrical/electronic engineering degree. I am horrified at the idea of legally allowing unqualified members of the public to repair or install domestic wiring. Some of the jobs I have had to repair/upgrade that have been completed by do-it-your-selfers have been really frightening. Knowing Ohms Law is just not enough and unfortunately not everything is obvious to the uninitiated.

What really concerns me is safety, for the owner and for the next poor bugger who has to come along and upgrade or repair a job that has been completed with good intentions but has ended up being a death trap.

I agree that anyone that has the skills should be able to attempt work in their own home, but they should be tested by an independent body to ensure at least at some time they have a thorough grasp of all the knowledge they require to complete the job safely.

I can also appreciate that just because a person is licensed does not mean that the person is capable. I think that electricians should be re-tested every five years but that is another matter.

Matthew Nicholas, via email.

Comment: we are not advocating any change to the way in which most electrical work is done. However, we ARE advocating that Australia adopt the same system as in New Zealand and a great many other countries whereby homeowners can do their own wiring, subject to inspection by licensed inspectors. This system works very well.

New Zealand’s electrical fatality rate is lower than Australia’s. And most of Europe, where homeowners are also permitted to do electrical work, has a much lower fatality rate. Apart from that, it appears that electrical fatalities in Australia due to homeowners doing electrical work is extremely low.

Valve amplifiers still wanted

Some time ago, the Editor made comments regarding recycling electronic devices, etc and ultimately you produced the Ultra-LD amplifier in an old computer case (March, May & August 2000). Well, it WAS ‘recycling’ but only just! Now the valve brigade (read "Luddites") are going to continually niggle and annoy you until you give in, so you may as well do battle with them now rather than later.

Two of the biggest headaches with valve amplifiers are the power supply and output trannies. What about using a monitor PSU for HT as well as the filaments? I recently junked a 14-inch colour monitor and the PSU board had outputs of 140V at 400mA, 80V at 200mA and 5V at many amps; in all, about 150 watts.

Now the 140V is a limiting factor but with decent efficient speakers and playing REAL music, 10 or 15 watts ought to be ample. Or how about a high-powered headphone amplifier?

Regarding the output transformer: go the whole hog and direct/capacitor couple. This will solve the design/price problem and the "Valve Brigade" will get so bogged down with faction fighting (transformer vs. direct) that they’ll leave you alone for awhile.

Seriously, I don’t know if PSU noise will be a difficult problem but if all else fails, run a competition for the best Universal Filtering Circuit. And you could put the whole thing into ANOTHER old computer case.

James Longmire, via email.

Comment: your idea about recycling a monitor is intriguing but it doesn’t really stack up unless you only want a couple of watts output. Nor is the idea of capacitor coupling to the output practical unless you have special high-impedance speakers; eg, the 800-ohm speakers made about 30 years ago by Philips.

We could do a valve stereo amplifier but it would probably leave very little change out of $1000. Even then the performance would be inferior to any of our transistor amplifiers.

Feedback on editorial content

I really appreciated your editorial in the June issue. While electronic product design and development for me finished some years ago, I remain in touch with the technologies (or at least I pretend I do) by building and experimenting on my workbench. That includes, from time to time, building some of the excellent designs from SILICON CHIP. And I certainly understand how much effort must go in from all of your team, to getting those designs and the magazine itself, out on time, each and every month.

And I enjoy the mix of articles. I don’t really appreciate Vintage Radio but I do appreciate your articles on the subject. Same for model aircraft and the recent series on UAVs. Not my field but I have enjoyed Bob Young’s material, very much. No complaints about the computer articles. They seem reasonably balanced, to me, with other material in the magazine. These articles often come in handy when I’m trying to sort out my systems and family PCs, etc.

The first page I turn to (well, of course, after the editorial!) is always the Serviceman. It would be interesting to see a feature on the cartoonist. He deserves a medal for his continuously superb artwork. How does he get his inspiration? Has he ever met the man? What’s his interest in electronics? Is he a freelance artist, or is he actually the marketing manager of Telstra with a secret life?

One of the biggest problems in the hobby, and one I think which has some impact on its potential to interest younger readers, is the scarcity and cost of components. I know that Dick Smith Electronics and others continue to offer fine service, for which I’m grateful. But if you want something a little out of the ordinary, like a Murata ceramic 455kHz AM IF filter, you’ve either got to junk a cordless phone or buy one from the Web at one-off prices with postal costs that are scary.

As for those months when your articles don’t quite seem to make the expected impact: I’m reminded right now of articles such as the command control trains series back in 1998. They didn’t much interest me back then but now with my son suddenly intrigued by an old train set, well, out have come those magazines and we’re both into it with keen anticipation.

Andrew Woodfield, via email.

Comment: thanks for the feedback Andrew. Our cartoonist does know the Serviceman – they meet each year at our Christmas party. Brendan Akhurst is a freelance cartoonist with a number of syndicated cartoon strips. We feed him the ideas which he mainly ignores and then comes up with his own crackpot concepts.

New computers are not so efficient

I know you’ve talked about turning PC monitors off when not in use and now I’m hoping you can enlighten me as to the logic in the ATX computer power supply. The power switch on the front of the box doesn’t turn the mains off. It puts the box in sleep mode or something. What I don’t understand is, when we used to turn off the front or side power switch to our PC, we turned off the mains and it used NO power at all.

Now we push the button and it goes to sleep, still connected to the mains and consuming the 5W or so to keep it alive. This is energy efficient, I’m led to believe. It also allows such functions as "wake on LAN" and the like.

What I can’t come to grips with is all those PCs that AREN’T used in the above way (ie, standalones with no need for such functions as wake up on LAN) sitting there consuming their 5W whereas before they consumed NOTHING. How many PCs on this planet are consuming their 5W doing nothing and how much generating capacity, producing greenhouse gas emissions, is required to keep them all going when they are doing nothing? I do not believe folks reach around the back and turn the real power switch off!

Do the power supplies last longer due to being on all the time? I don’t think so. Can you please tell me how a device consuming a small amount of power is supposedly more efficient than one which consumes no power at all?

Brad Sheargold, via email.

Comment: don’t you accept all the good stuff that the companies keep telling you? Of course the new power supplies are more efficient – it is just that they keep using 5W when they go to sleep. If you add all the appliances in your house which are supposedly asleep (ie, on standby) you will probably find that you have a standing power consumption of at least 100W (add em up – VCRs, microwaves, plugpacks, TVs, dishwasher, etc). That costs you around $100 per annum.

We still reckon you should switch off your computer and pull the plug out of the wall when not in use.