Tribute to Ray Kelly

I was most impressed by the article by Rodney Champness in the Vintage Radio section of the December 2005 issue. What a marvellous statement of historical facts on the efforts and background of Ray Kelly of the Historical Radio Society of Australia, and the creation of the HRSA.

The detailed article is a tribute to a marvellous and gentle man with the foresight to realise the importance of radio, both as a part of our lives and as a technical, manufacturing and broadcasting enterprise in the development sense of Australia’s radio heritage. Ray was able to retain at least some of the finer examples of our radio history (the physical items and a plethora of printed data) before it was relegated to the many local tips. Because of the efforts of Ray and a small number of others, we all have a very clear and ongoing focus on Australia’s radio history.

The article serves as a wonderful and timely tribute to Ray, as Member Number 1 of the HRSA. Sadly, as noted in last month’s issue, Ray Kelly passed away on Saturday, 19th November 2005.

Graeme Dennes,

via email.

Nuclear power: we just need to wise up

In regards to your Publisher’s Letter in the January 2006 for expansion of Australia’s nuclear power program, I’m sorry to say, as you probably are aware, it’s a foregone conclusion. Here in South Australia, the large expansion of Olympic Dam mine will ensure that. Maybe you should visit that site and have a drink of the water, after another recent incident.

It’s easy to see fission nuclear power inevitably costs more, because an extremely dangerous product must be safely extracted, used, transported and contained following use for an indefinite period of time. And there is also the cost of storing large sections of future decommissioned plant.

Worse still, all this will happen here, against the will of the majority. There is plenty of free SAFE energy from nuclear power below the Cooper Basin and Hunter Valley regions to name a few – several thousand times the amount we need to power this continent.

We just need to wise up and get it.

Jeff Peate,

via email.

Nuclear power has too many problems

Your editorial about nuclear power in the January 2006 issue was as hot as the weather we are inflicting on ourselves. Yes we do need to come up with solutions to our growing consumption of power and resources. What we need is careful consideration of our options, not adherence to the "big toys for big boys" syndrome – especially a 50-year old relic that is still floundering with unending problems: public subsidy, (non) waste disposal, decommissioning and the enormous human tragedy of accidents like Chernobyl.

The disposal in the NT you refer to is for low-level radioactive waste, such as medical, industrial and now consumables such as smoke detectors, which has been accumulating since the 1950s. It is not geared for reactor waste as you intimate in your editorial. The design approach is simply trenches in the ground.

Paranoid? Yes and justly so, when someone with your position so happily expounds on a subject which you obviously have scant knowledge of. "There is no operational pollution". Really, please explain what happens to the radioactive gases routinely vented from reactors. There are no known methods for sequestering these, in particular the inert gas isotopes.

There are alternative options already available and working. As you say, solar and wind may only make up 20% of the mix. The salient point is they don’t yet. One simple policy change, deregulating the electricity market to allow individual homes to sell their excess power (as in Germany where their solar industry is now ten times Australia’s) could offset air-conditioning demand, for example. At present, utilities give power credits to grid-interactive systems!

Intelligence not gumption is called for.

Rory Shannon,

Goongerah, Vic.

Comment: nuclear power stations do not routinely vent radioactive gases. And yes, Australia could do much more to use solar and wind power and be much more efficient in energy use. But we still need more power stations.

BPL is bad technology

Paul Budde’s comments on BPL in the January 2006 issue demonstrate only that he doesn’t have the foggiest idea about HF propagation.

You cannot defeat the laws of physics. If you inject RF into unshielded wiring at ANY power level, you WILL create interference with wireless services using the same spectrum. That’s it, end of story. I don’t know where he gets 500,000 potential users from either. If he thinks it will be competitive to deploy BPL in areas where wireless or ADSL (forget cable) are not feasible, he had better do the sums again.

Even if only 1% of broadband is supplied by BPL in this country, it could still make enough RF noise to make large sections of valuable spectrum unusable or greatly impaired for 1000s of kilometres.

He mentions that it is deployed in many places, one of them Asia; carefully omitting the fact that the largest economy in Asia, Japan, has knocked it on the head for these reasons, as have other administrations in Europe.

Most deployments at this stage are experimental. All of them are controversial! He only mentions Radio Amateurs and therefore implies that they are the only people who have expressed grave concerns and opposition. The Department of Defence (I hope they are not amateurs), Department of Civil Aviation, Australian Broadcasting Corporation and many others have great concerns.

So please get real. BPL is BAD technology and no amount of spruiking will improve it.

Horst Leykam,

via email.

Alternative approach to Jukebox Just thought you may be interested in my Jukebox/Arcade Machine. Just for interest, have you thought of using a keyboard hack with yours? This involves cutting up an old keyboard and wiring the circuit board to some buttons (1 to 9 and next random etc). This makes it very hard to damage and almost idiot-proof in operation. Chris Dunn, Nowra NSW. Comment: your Jukebox looks very impressive. We did not consider a keyboard hack as we wanted to keep the wiring as simple as possible.

Dead VCRs have useful power supplies

Don’t throw out dead VCRs. You can often strip the power supply from them. Typically they have at least one 12V rail you can use for projects.

Generally, they also have a couple of 30-40V rails, and these can be used too, if you put a 3-terminal regulator such as a 7812 in front of them (not for high current or the regulator will self-destruct!). The rails are usually good for at least 1A, sometimes more. The mains transformer is all mounted and ready to go, so no dangerous mains wiring. In fact, with most VCRs, the mains lead plugs directly into a PCB header on the PSU module.

I don’t recommend the use of switchmode PSUs (as they can bite!) but there are hundreds of older VCRs with transformer-based PSU designs sitting in junk heaps.

National/Panasonic PSU modules are good because most of the time, they even insulate the mains parts of the PSU for you, making them even safer.

Also worth stripping are the DC motors used for the carriage loading mechanism and tape guides cue-up. These are generally 12V motors, very useful if you are into robotics.

Graeme Rixon,

via email.

Adaptive cruise control a major concern

I read your article on Adaptive Cruise Control Systems (SILICON CHIP, September 2005) with a mixture of interest and deep concern. What percentage of "road accidents" are due to the stupidity, poor attitude and training of the driver, rather than "road conditions"? No level of technology applied to a motor vehicle will ever overcome the stupidity, etc of a driver.

This brings me to my main concern about vehicle safety. Any system in the vehicle that allows the driver to reduce their concentration on driving is dangerous!

Cruise control maintains a theoretical constant speed and the driver may be tempted to concentrate momentarily elsewhere. With ABS (Anti-Lock Braking System), the driver may be tempted to drive at speeds greater then conditions allow, thinking the braking system will handle any errors they may make.

ESP (Electronic Stability Control) is even more insidious, as the driver may be tempted to corner at greater speeds or change lanes more aggressively.

With Adaptive Cruise Control, again the necessity of driver concentration is reduced. The system maintains a safe distance from the vehicle ahead without driver input.

The only means of reaching the safety goals as outlined in Fig.1 of your article would be to produce a fully computerised electronic traffic control system embedded in each lane of expressways, freeways and arterial roads. One would then have to hope the system would not "crash".

Col Hodgson,

Wyoming, NSW.

Comment: some drivers do relying on ABS to shorten braking times. However, for most drivers, technical innovations represent an improvement in driver safety and comfort. And on a long journey, cruise control is a real boon.

Adaptive cruise control radar questions

I read the interesting article on adaptive cruise control in the September 2005 issue. This raises questions regarding all those radar signals bouncing around the highways when these systems become more common.

(1) How does one unit tell that it is receiving its own return signal and not one from the identical vehicle beside it? Is the signal coded in some way like the conversations in CDMA phone calls?

(2) What happens to the police radar units with all these extra signals bouncing around in the field? Police claim to be able to detect radar detector detectors (if these are only receivers I don’t know how they can do this – can you explain?)

So with all the extra pollution from ACC units, are there going to be erroneous speed offences issued? If the fixed speed camera on the Spit Hill can clock a bus going uphill doing more speed than its capable of on the flat, does this new technology open a Pandora’s box?

(3) Will all this additional "microwave" energy at ground level create a situation where the "technophobes" in our society claim that it is dangerous to children and other living things. As you are aware, they all have a shoe phone but don’t want the towers to make them work! Is the power output of ACC radar greater than a mobile phone tower when the inverse square law is taken into account in the relatively shorter distances involved?

Brad Sheargold,

Collaroy, NSW.

Comments: these answers are directly quoted from the Bosch publication on Adaptive Cruise Control.

(1) Radar sensors only interfere with one another if they are operating simultaneously within the same frequency band. A number of properties on the part of the radar sensors ensure that if this occurs, it only does so very sporadically.

Firstly, the radar beam is only
activated for the precise period that it is actually required. This alone reduces the likelihood of mutual interference to less than 10%.

Secondly, the FMCW modulation ensures that for each time unit, only an effective bandwidth of less than 500kHz within the frequency range 76-77GHz is used. This makes mutual interference between radar sensors extremely unlikely.

In addition, filtering and plausibility-checking of measured data ensures that interference signals do not cause the vehicle to react incorrectly.

In practical terms, therefore, mutual interference between radar sensors is virtually impossible.

(2) The ACC SCU produces a radar beam with a frequency in the range 76-77GHz. That is equivalent to a wavelength of approximately 4mm. Because of the high frequency of the beam, its effect on humans is comparable with that of heat radiation (infrared range). The average emitted power is approximately 1mW and is thus at least 500 times lower than the radiation from a mobile telephone.

Research has shown that this level of radiation is absolutely uncritical in terms of its effect on sensitive parts of the human organism. Even pointing such a beam directly at the human eye has no known negative effects.

(3) Police speed-enforcement equipment is not affected by ACC systems. As far as radar equipment is concerned, it operates at much lower frequencies (<35GHz).

Washing machine pressure switches

Your "Salvage It!" article on washing machine pressure switches has prompted me to write.

As a Volunteer with Technical Aid to the Disabled Qld, I was asked to help a client who has MS and could not use her legs to control a sewing machine. Using a pressure switch and an old PMG switch modified to suit the purpose, Christine now is able to start and stop the machine, sucking on the tube to start and blow to stop.

The amount of suck and blow determines the speed.

Fred Nott,

via email.

Anchoring wires to PC boards For some time now I have been going to make the following suggestion about terminating wires to PC boards. Most of your projects either use PC board stakes to which the wires are attached and soldered or have the wires inserted directly into holes from the top of the board, as with any other component pigtail. The problem with this approach is that with either method, the ‘flexing point’ for the wire is rigid due to the capillary action of the solder up the (stranded) wire. Any unnecessary movement of the board, as when fault-finding a newly-constructed project, will flex the wire at this inflexible joint and it will inevitably break! I know! I design and build all sorts of gadgets, am lazy and most often just tack wires for external connections to the print! It is so frustrating trying to trace some boo-boo only to have an unnoticed broken connection adding to the problem! Years ago, in a more professional capacity, I used the wire termination techniques illustrated below (C&D). I suggest that this is a far more satisfactory arrangement and prevents the air turning blue when one finds an unexpected broken connection when chasing down another fault. Recently, I have reverted to this technique, even on some of your kit projects, with far less strain on my patience! Expensive? Yes, sometimes it is in a production situation when the added time required to thread the wire through an additional hole adds cost to some cost-critical unit! For home projects, this is of little importance. The added holes (of sufficient diameter to accept the insulated wire) may add a small cost to the PC board but in situations where PC stakes are contemplated, maybe a cost saving could be realised! Examples A and B show what I mean about direct soldering either to a PC board or to a pin. The methods shown in C (for leads which can exit from beneath the board) and D (for leads which must exit from above the board) are far more secure! The technique for the home constructor for making such a connection is to thread a convenient length through the "anchor hole", sufficient to make the joint comfortably, then pull back the excess until everything is neat and tidy. Simple! In production situations where a solder bath is utilised, the wires were bundled on top of the board and threaded through the anchor holes later. Colin Hiscock, via email. Comment: we agree that wire flexing can cause fractures but your method of anchoring could lead to much frustration when they have to be disconnected, perhaps repeatedly. For that reason, in recent designs we have been using screw terminal blocks for wires which are likely to need easy disconnection, as in our amplifier modules.