Thanks for prize

I was delighted to win the WaveTek Meterman multimeter with my August Circuit Notebook item. It is a very welcome addition to my test equipment arsenal. My thanks to SILICON CHIP and Fluke Australia for this great prize.

Andrew Partridge,
Kuranda, Qld.

The magic of PMPO

With reference to J. R.'s letter in August's "Ask Silicon Chip", I recently noticed a Ghetto Blaster for sale in a discount store. It boasted 120W PMPO!

Intrigued, I looked at the back of the machine to discover that it was powered by six D cells. My maths says that 120W from 9V DC (no power factor problems) means 13.3333A, not counting the motors or any losses. The loudest noise would have to be the squeals of pain coming from the D cells.

To the manufacturer's credit, the recommendation was to use alkaline cells but . . .

Brian Wilson,
Curtin, ACT.

Sooper Snooper could be used illegally

I am more than just a little disappointed at the lack of legal disclaimer associated with the article on the "Sooper Snooper" in the September 2001 issue. Reference to the Surveillance Devices Act 1999 shows that your article incites, no less than three times, your readers in Victoria to break the law. Nowhere have you made mention that the use of a listening device may be illegal in some states. The three locations I have found are the first line of the introduction, paragraph two and paragraph ten.

Specifically, the Surveillance Devices Act states that a person must not knowingly install, use or maintain a listening device to overhear, record, monitor or listen to a private conversation to which the person is not a party, without the express or implied consent of each party to the conversation.

Normally a professional magazine, this uninhibited disregard for the legislation of this country is unacceptable. I trust that you will issue a legal disclaimer in your next publication.

Ian Stanley-Eyles,
via email.

Comment: readers building the Sooper Snooper project should be aware of the relevant clauses in the above Act. The full text of the Act can be accessed at: http://www.dms.dpc.vic.gov.au/

Electrical fatalities are not caused by homeowners

I'm not sure whether you've published the following information before. I recently completed a TAFE course on electrical inspection and testing (course # 5661F – commonly known as the "tag & test" course) here in Wollongong. This entails a 2-day course, where the basic principles of AC power transmission and terminology are taught, along with basic concepts (voltage, current, resistance, etc) and workplace testing and safety procedures were introduced.

Part of the course is to learn how to use a 'megger' device, in order to perform electrical tests on cables and extension leads. Another part of the course is to actually make (under supervision) a 3-pin extension lead, test it and then 'tag' it as safe. The funny thing is, we were told by TAFE teachers several months ago, that once we had completed the course, we could be either licenced by WorkCover or Fair Trading, so that we could independently test equipment.

When I recently approached both bodies however, I was told that neither of them had ever heard of any such arrangement. The only licences available in NSW are the full electrician's licence, or the 'restricted' (because it's still restricted to only the chosen few?) licence which allows certain people to connect/disconnect fixed wiring, as part of what they normally do (eg, plumbing, etc). It looks like the 'old boys' club strikes again. What's the point of training someone to use a megger and a DVM, and then telling them that they can only use an approved test machine (eg, Safe-T-Check) and more to the point, why teach someone how to make up a 3-pin extension lead, if they're not allowed to do it for a living?

Perhaps another pertinent point is that of manufacturing. There must be literally hundreds of people on factory production lines around Australia, making up leads, power supplies and other high-voltage equipment and accessories, that eventually consumers will use. Just how "qualified" is a factory worker to make, inspect and test such equipment and what TAFE course have they done in order to prove their competency in this area? The issue is why can an unqualified factory hand manufacture equipment, that people with years of training and experience are forbidden to work on – even if it is just a part of their hobby?

As a result of all of this, I believe that people are being trained to do what some electricians regard as their 'dirty work' (tag and test, etc) but those who gain the TAFE competency based 'statement of attainment' will in no way be rewarded with anything that looks like a licence or permit, that will allow them to operate as independent contractors. We were told very strictly in class, that this course does NOT make us into manufacturers or repairers (we probably can't even legally repair the 3-pin cord that we made as a class exercise – what a farce!)

There were several other startling developments that were revealed to the class during my brief time at TAFE. They were:

(1) In 1999, of the 10 electrical fatalities reported to the NSW Department of Fair Trading, eight concerned licenced electrical contractors, who were careless when working on live power installations (FT report B-15, for January 2000) while the other two concerned non-tradespeople who came into contact with damaged or unsafe equipment (an unearthed fridge and a broken light bulb).

(2) The TAFE lecturers, themselves licensed tradespeople, let slip that the whole electrical industry will probably be deregulated over the next three to five years anyway. One of them also mentioned the industry deregulation in New Zealand.

Name supplied but withheld at writer's request.

High current is not problem

50 AMPS, run for the hills, Ma Baker. Peter Raffaelli, what a man! I just loved his letter in the September 2001 issue. Electricians love to tell you that they work with AMPS and that limp-wristed techs work with milli/micro amps. (squeak, squeak). As T. Bradley pointed out in the same issue, working on substations or any other field where high voltages and currents are present doesn't rate a mention when trying to get approval to do some house wiring. For the record, milliamps can kill you just as easily as amps can.

As for Joe Bloggs getting the Active/Neutral wires around the wrong way, this can be easily explained. People are told that their house wiring is AC. This is only partially true. The Active wire has an AC voltage on it while the Neutral is at the same potential as the Earth wire. If, indeed, your house received a true AC then both wires (active/neutral) would reverse polarity periodically. Then there would be no problems as to which side either wire was placed. This is why the consumer can come unstuck, through misleading information.

I do not think those who want change are for an open-slather approach; just one that is fair. Nobody wants people dropping like flies from being electrocuted. If you looked up the statistics, you would probably find that a large proportion were electricians.

Peter mentioned the National Restricted Electrical Licence. This amounts to nothing more than being allowed to connect/disconnect hot water systems. A lot of people, especially electricians think (quite wrongly) that the Licence gives you the right to put in power points. Just don't try it as you will be in for a big shock. And a bigger fine.

Changing laws can be a time-consuming business. It's better and quicker just to add a few clauses to the Restricted Licence. They being;

Clause 1: The holder can move or add power points, light fittings and switches to existing wiring.

Clause 2: Builders of kits or any design that incorporates the inclusion of transformers that need to be connected to mains power can do so.

There needs to be a minimum amount of knowledge held by the person applying for the Licence; having done and passed Electrical Principles 1 and 2. This at least shows knowledge on the subject.

I. Moore,
Port Macquarie, NSW.

DVD picture quality can be very good

I read with some astonishment the letters from Brad Sheargold and John Richardson in the October 2001 issue. My experiences with a Grundig widescreen (CRT) 100Hz set and an inexpensive Toshiba DVD player have been uniformly superb.

Perhaps the Fujitsu plasma display mentioned was set up incorrectly or some experimentation with the DVD player setup menus was needed. I have been delighted with the video (and audio) quality of my reasonably modest setup, viewing 40 or 50 different DVD movies so far. Certainly it has been unnecessary to spend $10,000 on a posh player.

I have also watched DVD movies on a large Philips plasma screen elsewhere and was very impressed. If
my available budget had been large enough, I would have bought that screen on the spot.

As for widescreen TV problems, I will agree that the digital TV broadcasts can sometimes change format at frequent intervals but do not find this particularly disturbing as the TV is set to expand the picture to fill the screen. It does this in a nonlinear fashion, with 4:3 pictures expanded most at the left and right edges so that the resultant effect is almost unnoticeable. The thought of returning to VHS fills me with horror, with its far worse picture quality, though passable sound.

I am extremely conscious of picture quality as I regularly enlarge medium format colour negatives to 40 x 50cm and am used to critically assessing the results. It is certainly true that watching a widescreen DVD movie on a 4:3 set is not a fabulous experience. However, use a 16:9 set of even moderate size and the difference is huge.

Perhaps I have been fortunate in my choice of TV, player and DVD movies, but it seems unlikely that I would never have encountered any of the problems mentioned in the above letters if such problems were as common as claimed.

Ross F. Hall,
via email.

Videoscope a timely project

Thanks for the VideoSCope in the October issue; just the project I've been looking for to get my sproutcam (webcam 2 at http://www.woa.com.au) back and operating again. It was a case of forehead slapping as to why I had never thought of that. I even have three old 50mm (1 x 28mm & 2 x 135mm) lens floating with bits of 50mm pipe.

Could I put in a request for a PCM-controlled bicycle lighting system? My particular interest is long distance with recharging from hub generators.

Terry Collins,
via email.

"Mantel" vs "Mantle"

Thank you so much (once again) for providing us with a "real" Australian electronics magazine. It's good to see that Jim Rowe and others have joined your team of authors.

Sorry to be a bit nit-picky, but would you please tell Rodney Champness (in the nicest possible way, after a large thank-you for his articles on Vintage Radio), that the sort of radio he is referring to is spelled "mantel", not" mantle".

Like mantel clocks, they sit on a mantelpiece.

David Pulford,
Forestville, NSW.

Refinement for Videoscope

Thank you for another brilliant project in SILICON CHIP. I am referring to the VideoSCope in the October 2001 issue. I have built it and find new uses for it every day. However, one aspect which could be improved is the camera mounting plate or more specifically, how to fit it into the joiner and get the cable and gland all into position. It is very fiddly and I found I got very frustrated with it until I came up with a brilliant idea.

Simply cut or file a groove in the round mounting plate the shape of the cable from the camera. This will allow the camera to be fitted to the plate, cable to be fitted to the camera and protruding from the hole in the mounting plate. This then allows the whole assembly to slip into the joiner with the groove allowing the cable to pass, then the gland is fitted and after that the retainer piece is fitted.

The accompanying picture shows the modified plate I used.

Colin Leonelli,
via email.