Smart card article unnecessarily coy

In the January 2003 article on the Smart Card Reader/Programmer, I was surprised by your coyness in not wanting to supply the software! I simply do not believe what you say on page 18 about Australian federal law. I use exactly the same software in my Atmel programmer kits. It is trivial - serial port, I₂C, MAX232 to data I/O! The only difference is the Smart Cards are not in DIP packages (and they are Microchip, not Atmel brand).

All chip programmer software always has a Read option. So if you follow the same logic you would not be supplying microcontroller programming software because, like a pencil and paper, it could be used to defeat encrypted systems! Security issues with Smart Cards are well discussed on the web.

There is an excellent introduction to smart cards at: http://egov.gov/smartgov/tutorial/smartcard_foyer.cfm

Peter Crowcroft,
DIY Electronics (HK) Ltd,
Hong Kong.

Credit to Edwin Armstrong

Regarding Andrew Woodfield's super-regenerative receiver article in December 2002 magazine, some credit is due to Major Edwin Armstrong, US Army, for his invention of regenerative, super-regenerative, superheterodyne and FM receivers, in the early valve age of electronics. Super-regenerative receivers were used extensively in WW2 due to their high sensitivity at VHF and economy of valve numbers.

Their most important and numerous use was in VHF, IFF (Identify Friend or Foe) transponders, fitted to Allied aircraft. Super-regenerative receivers were also used in portable battery operated VHF transceivers and radar beacons.

Back to Andrew Woodfield's super-regenerative circuit, a single turn coil link coupling to L1 is another way of connecting an external antenna to the detector's inductor.

On another subject, Garry Cratt's article on satellite TV (also in the December 2002 issue) made the statement that the BBC no longer transmits on shortwave. The BBC can still be heard in Australia on shortwave, although not intended for us, directly in English.

J. Grace,
Kirrawee, NSW.

Comment on Serviceman's Log

In regard to the Sony television from South Africa in the Serviceman's Log section of your January 2003 issue, the set is described as having an FM receiver built-in, yet only being mono. The reason for this (and I have a Philips set with this feature from South Africa) is that you can broadcast TV programs in more than one language. While one language is attached to the main TV signal, the FM tuner can pick up another.

In Australia, the system was probably used for stereo though the two sound channels would be used simultaneously on two separate speakers. I hope this clears it up for you.

I would also like to mention that your SC480 looks very good and that I will soon upgrade my amps! It is great that I won't need to buy another case, transformer, output transistors, caps, bridge, etc since the new one literally drops into the old one's place without much cost at all! Well done.

Rory Shillington,
via email.

Extending memory in VCRs

If we turn the power off at the wall socket instead of leaving our VCRs, etc on stand-by, we can save on our electricity bills. That is all very well but when we switch the power back on we have to reset the clock, or do we?

I have a Philips mono video which has a super cap to hold the memory for a short time. By adding a one Farad super cap to this I was able to extend this time to over 40 hours which suited my requirements. To get the same time on my Panasonic hifi video, I had to fit three one Farad super caps. I hope this is of interest.

Cyril D. Vickers,
Elizabeth Downs, SA.

Circuit Notebook policy

Would it be possible for you to publish an article concerning your magazine's policy on what it will or won't publish in your Circuit Notebook section?

For example, will you publish valve circuits, improvements to existing designs or improvements to designs in long-dead magazines? Are you prepared to use two pages for one design submitted and how good does it have to be before you want to touch it?

As a matter of policy, everybody would like to know where they stand.

Gregory Freeman,
Mt. Barker, SA.

Comment: in general, we don't publish valve circuits, unless they are featured in the Vintage Radio pages. We would not rule out publishing improvements to circuits from deceased magazines; eg, Electronics Australia, ETI, Popular Electronics, AEM, etc.

Some designs featured have run over two pages (see this month, for example). How good does it have to be? Hard to answer - innovative, novel, clever, simple and complex circuits can all get a run.

Many homes have unsafe wiring

The Victorian union attempt to outlaw electrical hardware sales for home wiring installations is another piece of stupidity. I feel that far too many homes are sold without the buyers being aware of the state of the wiring and a certificate of compliance should be issued. The same should be done for rental properties every four years or so.

As a dishwasher serviceman, I have seen many instances of dangerous points wired behind the dishwasher, with it in turn being tiled into place after installation. This makes removal and disconnection from live wiring impossible, as well as extremely hazardous in case of fire or malfunction. You could not turn these off if you wanted - the only way would be via the main fuse box.

John Vance,
Melbourne, Vic.

Government/union bashing?

I have been reading your Publisher's Letters in recent issues. What on earth are you on about? Is this a bit of government/union bashing I detect. Where are your facts to support your statement that electricians are less skilled than TV/washing machine, etc repair persons?

At least to become an electrician you must attend an accredited TAFE course and pass the appropriate competency levels before your can call yourself an electrician. Have all repair people completed and passed the appropriate qualifications before setting up to call themselves qualified repairers?

I looked up the Queensland ESO site and read through the requirements of the legislation. It is not an Electrical Contractor's License that they are asking for but an Electrical Contractor Business License. You know of the "Gold Card" license, so that the customer has some protection against shoddy workmanship. No Gold Card, no work. Someone has to regulate these businesses and this seems to be the generally accepted method to have a government body to do this.

You also make light of the fact that no service person has been electrocuted on the job but I wonder how many of his/her customers have. How would you know this, because without any regulation they are not required to report any incidents? But an electrical contractor must under OH&S legislation report all incidents, or risk fines and loss of license.

I think you are missing the point of the legislation, which is to introduce some accountability on the service person part and to provide some guarantee to the paying customer that their work is of a minimum standard.

I could go on but then you might think I was just a disgruntled unskilled electrician.

Jeff Ezzy,
via email.

Comment: all electrical deaths are reported and investigated, no matter what the cause or circumstances. Our statement was that "there probably never has been a fatality because of an appliance fault caused by a repairer" (page 4, February 2003).

It turns out that there is just one recorded electrical fatality, due to a wiring fault in a repaired appliance - in a vacuum cleaner! This sole fatality is the only one recorded in Australian records going back some 50 years, in a population now approaching 20 million people. Plainly, this is a very tiny problem!

Another method for de-sulphating batteries

In the Circuit Notebook section of the February 2003 issue, you showed a circuit which claims to reverse sulphation in lead-acid batteries and you expressed some doubt as to whether it would be effective.

There is another method which reverses sulphation by using chemical regeneration. This method has been around for many years and definitely works. I used it on the 6V batteries used to power the underwater lights of flounder fisherman in the small coastal country town in which I lived in the early fifties.

The problem was that as soon as the flounder season ended, the batteries would go on the shelf in the shed and be forgotten. When the next storm started, not only would they be flat but also well sulphated.

Using the method described in "Salving Accumulators - A Simple Method" (Radio and Hobbies in Australia, December 1942) definitely did the job and yours truly made a little money as well.

David Allen,
Findon, SA.

Comment: we have the article on file. The method involves replacing the battery acid with sodium sulphate and then giving a long charge. The battery is then washed out thoroughly with distilled water and refilled with fresh sulphuric acid.

AC operation of halogen lamps

Just a note to thank you for the review of "Motor Home Electrics & Caravans" in the February 2003 issue.

The halogen globe life issue is a curious one. I recollect way back that they were only recommended for AC on the grounds that was necessary for the depletion cycle or something - but they are used extensively on DC (including by me). The (alleged) problem concerns only the 12V 10/20W globes - mainly the 10W units. Car headlight and other such globes are designed to run on 14.2-14.4V. They are far more rugged and as you say, work fine.

The boat people are adamant about this issue. You'll find any number of references to this in marine electrical manuals. We could all be wrong of course - the problem might be salt water, dirty DC or something else!

Collyn Rivers
www.caravanandmotorhomebooks.com

Loves the PICAXE article

Just wanted to say thanks for the a great article about a great little chip. As soon as I had read Stan Swan's February article about the PICAXE chip, I went onto the UK site and ordered some. They arrived in six days.

I set up the LED flashing experiment after dinner and it worked straight off. I then set about experimenting with it and now have it sending CQ in Morse. I can see a great future for this little chip and look forward to many more uses for them down the road.

Eric van de Weyer, VK2KUR,
via email.

Possible cruise control problem with LED tail lights

With regard to the LED tail lights featured in the March issue, you refer to the brake light out sensors giving incorrect readings if these are used. There is another piece of automotive equipment which may be adversely affected by the LED tail light replacements, namely cruise control (CC).

Many cruise control units use the brake pedal and stop lamp globes to sense when the brakes of the car have been applied, disengaging the CC unit. They use the cold resistance of the globes to take a sensing input to ground which allows the CC to be engaged. When the brakes are applied, this input goes to +12V as the lamps light, disengaging the CC.

If all the globes are replaced with LED units, the CC may not work as the input might not "see" a low resistance to chassis.

In regards to "lamp out" sensors and CCs, probably the best solution is to fit small globes in parallel with the LEDs and hide them inside the car. The rating of the lamp would be selected to allow for these sensors to work but this tends to defeat the purpose of the exercise (except for the faster turn on time of the LEDs).

Brad Sheargold,
via email.

Electrical contractors often negligent

Once all Queensland electrical appliance repairers are licenced as contractors, will it eliminate incidences of negligence investigated by the Electrical Safety Office? I don't think so! In reviewing electrical accident reports, I note that contractors and their employees are amongst the worst offenders on safety issues, often resulting in electrical workers, non-electrical workers and members of the public suffering electrocution.

Requiring all repair persons to become contractors will only skew the statistics, with less accidents due to "unauthorised" work and more accidents caused by "licenced persons". I can even visualise more accidents because the public will not pay high prices for a "licenced contractor" to replace faulty switches, power cords, etc and will just wrap them in more sticky tape and hope for the best.

Still, at least the Queensland government coffers will benefit from the increased licence revenue.

If states do go ahead and regulate that only contractors may purchase and install electrical products, thus cutting out the home handyman, I wonder if the manufacturers like Clipsal and HPM, and retailers like K-mart, the hardware stores, etc will suddenly wake up as they lose their lucrative DIY market?

(Name supplied but withheld at writer's request).

LED lighting is irresponsible

Five point five metres! With the Road Authorities, NRMA and others trying to educate the public to drive in a responsible manner, with a rule of thumb, suggesting not travelling closer to the car in front equal to two seconds at the speed in question, the distance at 100km/h is a reasonably healthy 55 metres.

Taking the official view that some people have a reaction time of up to 1.5 seconds, the March 2003 article on "LED Lighting For Your Car" is not in the public's interest.

It is up to the driver in front to drive his vehicle at a speed and so placed that the risk from a shunt from a following car is minimised - not place his faith in bright lights that give a mathematical saving of 200 milliseconds. Having the advantage of a 60-year history of driving Australia's roads and never been hit in the rear, your article belongs in the rubbish bin.

Jim McCloy,
via email.

Comment: how can you seriously suggest that our article advocates driving too close to the driver in front? Read the article again to discover what we actually said.

Regardless of which type of stop lights are fitted, safe following distances will always be required. However, anything which gives you extra braking time in an emergency must be worthwhile.

Your statement that it is up to the driver in front to maintain a safe following distance is puzzling. Surely that responsibility lies with the driver behind? We also understand that the rule of thumb is to leave a three-second gap to the car in front, not two seconds.