Sensor light with no manual over-ride
I wish to respond to the article in Ask SILICON
CHIP, page 97, May 2007 (and the response in Mailbag, page 5, July 2007),
regarding sensor lights staying on due to intermittent power glitches.
There is an HPM brand sensor, model 630/3A, that is set-up to
work in sensor mode only, with no built-in manual override (note: the 630/3 has
the built-in manual override). Power glitches, brownouts or switching the power
off, then on again within two seconds doesn’t affect it.
If you wish to install a manual override on the 630/3A, you can
simply add an external bypass switch.
Garden Suburb, NSW.
Satisfaction with Nixie clock
I just had to let you know that the Nixie Clock published in
the July & August 2007 issues is the best kit I have ever built. It took me
about 10 hours to complete and I was very careful to ensure correct alignment of
the various components.
My wife is so pleased and impressed by the Nixie Clock that she
has made room for it in one of her glass display cases. The clear Perspex case
really does make the Nixie Clock look incredible! Congratulations to David
Whitby and SILICON CHIP!
Simple tank indicator has drawback
The simple tank water level indicator presented by John
Williamson in the September 2007 issue does indeed perform exactly as he says.
However when I tried the very same idea a while ago the problem I had was that
the water in the clear plastic tubing was then exposed to sunlight and began to
grow some multi-coloured algae which I decided I didn’t want in my drinking
Comment: good point. The tube must not be exposed to
Reason to invert a laptop display
I have been looking for a way to invert the screen of a laptop
for about a year. I tried Google, online forums, etc and eventually gave up.
I therefore read the Serviceman’s Log for September 2007 with
great interest. It presented an easy solution to my needs.
Interestingly the Serviceman could not think of why anyone
would use this. In my case, the application is to mount an old laptop upside
down on the roof of my 4WD and use it to display navigation with a GPS and as a
large roof-mounted DVD player.
Climate change scepticism
There has never been any doubt that the publisher, Leo Simpson,
stands on the conservative side of the political spectrum but I would call him a
climate-sceptic rather than "denier" and some hard-nosed scepticism is certainly
needed with some of the self-serving "solutions" on offer.
Changing the area lighting on a block of flats to CFLs saved
considerable power but the biggest impact was from the longer life, meaning that
visits from an electrician at $80 per blown light globe were cut to one-third,
never mind better lighting. The much higher cost of the CFLs was recovered in
only a few months.
I’ve installed and maintained some remote area solar power
systems and I agree that they are quite uneconomic where mains power is
available. There are still large gains to be made in household energy
integration such as waste heat recovery from fridges.
The economy of solar-electric panels is reduced by charge
regulators that simply disconnect all those expensive watts, rather than
redirecting them to the fridge and homestead water pumps in a load-shed
However, I am at a loss to understand your swipes at solar
hot-water heating. If there is one thing that already significantly unloads the
urban electrical system it has to be domestic solar hot-water heating. The daily
shower gobbles a surprising amount of energy.
But it’s not often that I get a good belly laugh from a
SILICON CHIP editorial. After a couple of
swipes at "environmentalists" (whatever that means these days), Leo Simpson goes
on to demolish tree planting as a "net carbon sink".
Why I find this funny is that this very argument has been a
mainstay of the native forest logging industry (misquoting a CSIRO study). Only
a few years ago, it was "environmentalists" who were being derided for saying
exactly what you go on to say – the mature carbon-sink trees would then have to
be somehow totally removed from the eternal carbon cycle! That makes you as
green as a "Forest Feral" Leo.
Sadly, the arguments for CO2 as "landfill", electric
motoring and the nuclear fuel cycle still need similar cold scrutiny. In
contrast, geothermal power looks very hopeful at this point, not least because
the "waste" is not the stuff of parental nightmares and terrorist dreams.
Solar hot water systems should be
I have two comments on Peter Seligman’s recent articles on how
to cut greenhouse gas emissions. Firstly, concerning renewable energy from the
electricity grid, when the renewable energy source is not generating, there is
no electricity available from that source. Quite obvious really, so your energy
consumption must fall to zero; ie, the light should go out.
If it doesn’t, it must be coming from a non-renewable source or
some form of magic! Worse still, a fossil fuel machine needs to be running,
using fuel, waiting for the extra demand. This is known in the power industry as
Real renewable energy consumers don’t consume when the
renewable energy is not there! Otherwise it is not renewable energy – it is a
Secondly, concerning solar hot water systems, about 25 years
ago I lived in Papua New Guinea and developed an interest in "alternative
energy." My employer (Department of Civil Aviation) had numerous remote aircraft
radio navigational beacons and many were solar-powered (photovoltaic with
lead-acid batteries) and I had friends who were missionaries.
Most missionaries were in locations where there was no power
grid. Some had no electricity at all and for others, diesel-powered generators
met all electricity requirements.
Diesels have 40% or better full-load efficiency and could be a
source of hot water from the "waste heat" in the cooling system. I never
calculated overall efficiency but it would have come close to 50% at full load
with the waste heat recovery factored in.
Unfortunately, no one ran their machines all day. (6:00am to
1:00pm, and 4:00pm or 5:00pm to 11:00pm was common). Cooking was usually solid
fuelled (carbon neutral) and many stoves had a heating coil for hot water but
this form of water heating is not really "waste heat recovery" and won’t work
Solar heating was a viable alternative. Experience tells me
that with a sufficient sized collector and tank, there was no requirement for a
"booster". Most Australian commercially available solar hot-water systems at the
time were adequate in PNG. At my own home, I covered one or two of the three
collectors in the dry season as the water was too hot! I think it must have been
designed for Melbourne!
After some design research, it became apparent that these same
systems had a plate surface area that was about one third of that required for
Perth latitudes and the tanks were too small for the planned consumption. My
conclusion was that solar hot water systems designed for Perth were too small,
and deliberately designed to be "boosted!" As a corollary, solar hot water
systems, designed for the installation’s latitude won’t need boosting and
therefore will be truly "carbon neutral" in their energy consumption.
Hence, booster-free solar hot water systems are the correct
direction for reducing greenhouse emissions in domestic installations. Consumers
need to become aware of the difference and government needs to promote the value
of such systems.
New Australian Vintage Radio Society
Your readers may be interested to hear about the formation of a
new vintage radio organisation. The Australian Vintage Radio Society Inc is a
not-for-profit organisation dedicated to the preservation of our radio and radio
related electronic history.
Meetings are held on the fourth Saturday afternoon of the month
and visitors are welcome. Most meetings include a talk by a presenter with
experience in the field of restoration or history and a display of radios and
related equipment of the era.
Other services available to members include a bi-monthly
newsletter, technical assistance, restoration workshops, a valve and component
bank and a circuit diagram service.
Further details can be obtained by contacting the secretary at:
Australian Vintage Radio Society Inc, PO Box 3099, Syndal LPO Vic 3150. Or visit
our website at
1957 was the year I started school and the year space travel
commenced. October 4th 2007 was the 50th anniversary of the 3-week long flight
of Sputnik I.
At that time, my father was working as a scientist in the
CSIRO’s Radio Research Board (RRB) under Dr David F Martyn, based in the Sydney
area. This research group was investigating the structure and behaviour of the
upper atmosphere. The experimental side of this work involved transmitting radio
signals up and observing the reflected signals returned. This meant that there
was a selection of antennas, receivers and expertise available to receive
signals from the first spacecraft.
One Saturday afternoon, Dad and I drove to a building in the
grounds of the University of Sydney. I remember being in a room dimly lit by
outside light through high-blinded windows. There were large grey equipment
racks, some with dark knobs, glowing dials and lamps on front panels. I remember
one with a round green CRT display. There was the dull red glow of valve heaters
visible where there were no front panels.
On a work table there was an incomplete looking metalwork thing
and some cylindrical objects with wire pigtails. I had seen a similar sight in a
WWII bunker used by RRB near Camden Airport.
Various knobs were adjusted and then we waited, Dad attempting
but failing to explain Sputnik to me. Then it started, "bleeep bleeep bleeep
bleep". The explanations then became simpler. The sound was coming by radio from
90 miles above from the first man-made orbiting satellite.
My first thought was this was like many other bleeps I had
heard while near equipment racks. But I then realised my usually unemotional Dad
was keen to share both the facts and his excitement, about this scientific and
My recollection is that Sputnik I was not visible to the
unassisted eye due to its small size but that the final rocket stage was.
However, Dad said, these didn’t pass over Sydney at dusk or dawn and so he
couldn’t show it to me. I think the rocket stage was visible further south.
In the next month, on November 3rd, Sputnik II was launched.
This was visible in the evening sky from my home. We saw its star-like
appearance hurrying across the sky with its dog and, I assumed, bleeper.
Comment: thanks for sharing your memories of Sputnik, Graham.
It really does seem like a lifetime ago.
Refining the Studio Series Preamplifier
I have recently completed the Altronics kit for the complete
Studio Series Stereo Preamp (SILICON CHIP,
October & November 2005, April & July 2006) and was most impressed with
the supplied parts and overall performance.
An article in the August 2007 issue of SILICON
CHIP highlighted the superlative performance of the LM4562 op amp, even
putting the OPA2134 (as used in the preamp) to shame! I purchased a quantity of
the LM4562 and since it is a plug-in replacement, popped them in.
With the preamp connected to my AWA F242 Noise & Distortion
measuring set, it was obvious that something wasn’t quite right. Probing with a
CRO revealed 10-30MHz parasitic oscillations around both IC sections. Both
amplitude and frequency were dependent on volume control settings. Some lateral
thinking suggested that the op amp output feeding the volume control via
100-150mm of screened cable (and hence 50pF of shunt capacitance) was the
culprit. While the OPA has a gain-bandwidth product of 8MHz, the LM4562 tips the
scale at more than 55MHz!
The cure was quite simple: insert a 100-220W resistor in IC1a’s
(and IC2a’s) output feeding the volume control. This is easily accomplished by
lifting the "pot" wire on the PC board connector and inserting the resistor in
series with the screened cable and connector.
I was unable to measure any difference in distortion (little
wonder!) but the preamp’s total noise (20Hz - 20kHz, flat) was 6-8dB lower with
the volume control at "max" using the LM4562 op amp; well worth $25 for two
I also did some work on the potentiometer drive motor. I
purchased a dual 10kW ALPS Blue Velvet motorised pot (on eBay from Germany).
However, I measured a considerable increase in output noise (still around
-100dB) when the motor was activated. A few checks revealed that it was noise
radiated from the motor body, not the DC wiring. Two turns of mu-metal "tape"
around the motor body and secured with a cable tie removed the motor noise
The supplied toroidal transformer in the Altronics kit was
rotated to optimise the signal-to-noise ratio (SNR), there being a definite
sweet spot. The measured SNR on the F242 in dB terms didn’t show any reduction
but the residual noise improved dramatically from a buzz to a hum.
To find the correct orientation, the F242’s noise "monitoring
output" was fed into an audio amplifier and the resultant noise (more like a
raspy buzz caused by transformer stray leakage and/or magnetising currents and
possibly the diode bridge switching transients) was monitored on a speaker. The
toroid was gently (and carefully) rotated to null the resultant buzz (very
obvious!) with the volume set to 50% – the most likely setting used. The final
SNR was better than -105dB with a terminated input, the top cover in place and
using the LM4562s.
Speedo readings not good enough
I have read the recent letters regarding car speedo errors. I
find it quite disconcerting that manufacturers are permitted such a large error.
If I go into a supermarket and buy 100 grams of product, I expect to get very
close to 100 grams (maybe ±1%). I would be very displeased to find that I only
had 87.273 grams.
As you state, it must be very frustrating for heavy vehicles
with speed limiters set at 100km/h to be stuck behind a line of cars all doing
88km/h even though their speedos are showing 100.
Your correspondent Adrian Leake (SILICON
CHIP, August 2007) asserts that odometers are calibrated to read accurately.
My experience is that they read low. On several different 5km ‘Speedo Check’
zones my odometer read between 4.8km and 4.9km (2-4% low). A timed check of the
speedo shows that 100km/h is indicated as 108km/h, a fact that I can testify
can’t be too much in error as I drive on the highway with the speedo indicating
just below the 110km/h mark (approximate needle width) and have never had a
speed camera ticket although I pass a large number of cameras on various
Surely it is about time that car instrument manufacturers
caught up with the rest of the world and made instruments that indicate more
accurately the speed and distance. Perhaps even radar or GPS technology would
beat the old mechanical devices running off the transmission.
Some stereo TVs don’t reproduce stereo sound
Much has been discussed over the years about picture quality of
LCD vs plasma television sets. But I am not sure if people are all that
concerned about the quality of the audio from their new whiz-bang TV.
I recently discovered that at least one model of a well-known
brand LCD is incapable of producing stereo on all TV channels. It consistently
delivers dual monaural – ie, exactly the same sound from both channels – on
Southern Cross High Definition. The problem is also evident on ABC HD, WIN HD
and PRIME HD but it doesn’t seem to be consistent.
I’ve checked three other examples of this particular model and
this definitely seems to be not just a fault but a major design flaw in this TV.
It could very well be that there are other brands and models with the same
problem. My investigations have revealed that this model is incompatible with
the various audio modes being broadcast (see http://www.dba.org.au/index.asp?sectionID=14).
So if you are concerned about the audio from your TV, then have
a close listen. You might be surprised to find it is not performing as
I wonder if people really do "listen with their eyes" and could
be blissfully unaware of this problem.
Are mobile phones a hazard?
Like many others in our industry over the years I have followed
the debate over possible health implications associated with using mobile
phones. My background included control, communications and radar from 10kHz up
to 20GHz so I think I have sufficient knowledge to comment from a perspective of
over 40 years. Recently, a thought occurred to me on the phone issue and I would
like to put it out there for discussion.
Phone studies seem to vary from maybe there is to maybe there
isn’t a problem. In a similar manner to Scandinavia enforcing stringent
standards on the zoo of signals associated with CRT monitors, perhaps it is time
to examine how the phone studies were conducted and whether they were
appropriate or sufficient. Some studies were based on statistical analysis of
epidemiology data. Results were sometimes significant, others not conclusive.
I am cynical about any establishment and their ability to spin
a story to put the best face to protect their interests. It occurred to me that
physical studies were undertaken but very little detail of such tests is
available. The thought was, "Did the test take into consideration close
proximity of the mobile phones to the head?" I had been of the view that signal
levels were at such a low level that the risk was higher from base stations. I
did also consider a possibility existed that the pulse nature of the signal had
an ability to force resonance and perhaps cause problems with some
We traditionally think in term of far field radiation and not
the near field where the signal is launched, as is the case for mobile phones.
Wavelengths used for mobile phones ranges from about 30cm down to about 5cm for
some cordless phones. Purists will argue about the transition phase from near
field to far field but for general discussion the conventional value of half a
wavelength is sufficient. The near field for 900MHz phone services half is about
15cm and covers most of the brain cavity. This is also a problem for cordless
phones at 25mm but less so.
In the near field, the magnetic component predominates and this
is the issue that occurred to me. The near field being a magnetic field must
interact with our blood due to its iron content. I would be interested to know
if this has been considered. Any data obtained needs to reflect near field
locations and not more conventional far field locations. Suitable data that may
be available from radiography but such data would reflect a steady signal as
compared to a predominantly pulse signal. Also the phone "duty cycle" would be
higher. Have the hard yards been done or is part of our industry conveniently
sticking its head in the sand?
Am I a technophobe? Far from it. It is important that we
discuss such matters in a dispassionate way, unlike emotional mainstream press
coverage. As technologists, we know that at some level hazard conditions start.
Would a biologist studying radio illumination of a biological test subject even
consider or be aware of the difference between near and far field conditions and
possible differences in outcomes?
SBS is available from satellite
In the September 2007 issue on page 99 there is an item about
poor UHF TV Reception from W. M., of Lesmurdie, WA. His problem was that he was
unable to get SBS clearly in Perth, despite being just 6km from the
My suggestion is to get either a 65cm or 85cm satellite dish
and get SBS Free-to-Air (FTA) off the Optus B3 satellite with an FTA satellite
set top box. Have a look at Christian Lyngmark’s Lyngsat website
(http://www.lyngsat.com/optusb3.html) which shows what is on all satellite TV feeds.
Also, have a look down the bottom of Optus B3 list and you will
find Free-to-Air SBS with a KU spot beam over WA.
Tony Liolio VK2ZLT,