AM stereo turned off at 2BL
The ABC AM station 2BL/702 switched off broadcasting in stereo
a couple of months ago. The situation is dire. Virtually nobody broadcasts in
AM-stereo any more.
Spectrum is so scarce. Not maximising what we can do with what
is available is such a travesty. Given all the work SILICON CHIP and EA contributed to the format, I
was hoping you might have a few ideas about raising profile and getting some
Comment: since 2BL is mainly talkback, they probably figured
that no-one would miss AM stereo.
Another solution for SPAM email
Since I am plagued with between 40 and 50 spam emails a day, I
was interested to read 'What You Should Do About Spam' in the September 2002
edition. However, you did not mention the solution that I and other heavy SPAM
recipients have adopted in order to live with this problem. We have installed a
front-end or pre-processor program to our mail readers.
In my case, I use Mailwasher from www.mailwasher.net
which I bought for $US20. It has proved to be money well spent.
Mailwasher downloads ONLY the headers of all email waiting for
me on my ISP. I then check a Blacklist box for any obvious spam. Email I want to
receive I add to a Friends list. Emails I am unsure about I can click on the
header and the body of the message will start to download to the screen.
With practice one can judge within seconds if it is a real
message or another 'I have $US32 million trapped in a Nigerian Bank and I will
give you 35% if you help me to get it' type email. Clicking the Blacklist box
stops the download.
One can add wild cards to the Blacklist List to trap obvious
spam variations like email@example.com and firstname.lastname@example.org There
is also a Filter capability.
After vetting, one 'Processes' the emails. Blacklisted emails
are bounced and deleted. Genuine emails are down-loaded. In this way future
emails are preprocessed with my Blacklist and Friends Lists. Friends do not
appear in the listing while the Blacklisted ones appear for my
I do not see that one can stop email spam the way one can
totally block junk faxes. Spam email is worldwide and I regret I cannot see any
of your proposed solutions being effective. Preprocessing email is just part of
my routine to read my email. It is a price one has to pay for living in an
Internet world. Spam does not get me angry or frustrated. I never see it beyond
DIY Electronics, (HK) Ltd,
Long-term EA reader changes over
After EA changed their format, I pulled out when my
subscription ran out and emailed them to say they wouldn't last. While talking
to a friend with similar views recently, I did a check and found that my words
had come true!
We are both around the 50-mark and dedicated technicians of the
old school - both deriving an income from this trade incidentally!
Whilst I had continually heard of SILICON CHIP magazine, I had never bought a copy,
and so I find it amazing that you guys have taken over the complete history and
are continuing on with the very type of publication that has been going for
Donkey's Years that satisfies people like us!
I have immediately taken out a subscription but only for one
year, 'cos I don't trust anybody any more! I have every hope that your
publication will satisfy us - of course, I'll soon let you know if it
Thanks, guys. People like us will thank you for your efforts
and I hope will support you with input, etc. I certainly hope to supply some
input when I have had a chance to enjoy your product.
Rick Boston,R B Electronics,
Comment: thanks for your qualified endorsement. We have long
been frustrated by how long it has taken EA's dissatisfied readers to realise
that there was an alternative - us.
SILICON CHIP has
now been running for over 15 years and yet there are many people out there who have never bothered to even pick up a copy. If you know someone who would appreciate SILICON CHIP, please put a copy under their noses!
Support for fuel cell project
Just a follow-on from Jacob Westerhoff's email to the editor in
the September 2002 issue. I wish to add my support to his suggestion for
CHIP to come up
with a prototype fuel cell project.
Australia is not taking this technology seriously and therefore
falling behind in providing the next generation of scientist and engineers a
look into a small part of our future using this cleaner source of power
generation. The USA and Europe are putting millions of dollars into fuel cell
technology and research, to bring about change to our present internal
There are experimenters' type fuel cell kits in the USA and UK
but the exchange rate makes them very expensive. Therefore I agree with Jacob
CHIP should do a
follow-up article by providing links to where an experimenter can purchase the
parts needed at reasonable cost and start up a technology and experimenters'
Likes change to nanofarads
Well done on changing from .0047μF to 4.7nF, etc. It is certainly easier
to use, especially when you have to write or type the values out. By the way,
will you be moving to get rid of the decimal point. For example will you be
changing from 4.7nF to 4n7?
I was always led to believe that decimal points can be a
problem when printed and then copied a few times. Sometimes the decimal points
can get lost in the printing process, making values hard to read or at worst, be
incorrectly read as a different value. I came across this problem many times
when I used photocopies of photocopies of circuits with small print.
I guess though in such a clearly drafted magazine as SC that
should not be a problem.
Once again a great issue and I particularly found the article
on the Barlow Wadley receiver extremely interesting. I have a Yaesu FRG7 which
works on a similar system and performs very well. I pity the poor repair person
having to follow the circuit of the Barlow Wadley; it is drawn in a
non-conventional style to say the least!
Comment: at this stage we do not plan to eliminate decimal
points from component value labelling on circuits and other diagrams. While many
people like that approach, it entails yet another hurdle for the beginner to
Environmentalists are ranting
After Ross Tester's farcical article in March 2002 on solar
power, I was very close to writing a letter taking him to task over his
preposterous statements. Apathy prevailed, although I was pleased to see a
number of readers did respond.
Upon reading your October 2002 editorial referring to the "doom
and gloom" greenies, SILICON CHIP's attitude toward any environmental cause can be summarised along the
lines of "As long as it doesn't affect our comfortable lives or cost a couple of
cents more, all well and good, otherwise it isn't worth the trouble or cost". It
is a position that I am saddened and surprised by, given the scientific mindset
that you and your colleagues would most likely share.
As you wrote, the likening of the economy to an amplifier is
not new. In fact, it can be extended to encompass the effects of human
technology as a whole. Take for example our production of food. From foraging
and hunting, the burdening of beasts for tilling farms freed us from manual
labour and greatly increased food output. The time that was freed allowed
research into other pursuits which (among other things), gave us the industrial
Today, it takes only a handful of people to fell, sow, irrigate
and tend to great swathes of land. The vast majority of the population is fed by
the labours of a relative few. An impressive amplification indeed.
Similiarly, however, our industrial inputs and outputs (both
useful products and waste) have magnified with time. Keeping in mind the Earth's
biosphere is a finite source and a finite sink, the positive feedback of this
system will eventually hit a limit. Conventional economic thinking doesn't
recognise these limits and assumes consumption can continue unabated. The
environmental movement recognises these limits and seeks to place some negative
feedback into the system by maintaining the health of the biosphere which
ultimately supports us.
You rejoice in the fact that our lives and economy have
improved in the last 30, 40 and 50 years. This is only a tiny fraction of the
amount of time it has taken for the earth to generate the petrochemicals, coal,
timber and other resources on which our whole economy is hinged. Some resources
are renewable (eg; fisheries) however we deplete them at rates far in excess of
the natural restock rate.
Unless we are careful, it will take only a further fraction of
geological time before we have consumed all "banked" resources and are forced to
take only what can be sustainably restocked. Our current economically enriched
lives will become a curious and fleeting moment in history.
As publishers of a magazine, I believe you have a duty of care
in the views that you present and the influence it wields. I would highly
recommend that you read "Naked Ape to Superspecies" (ISBN 1865081957) by David
Suzuki. It may help you understand why the greenies are "ranting".
Comment: if you had read all the Publisher's Letters going back
15 years, and further back in "Electronics Australia", you would know that we
have deep concerns about the environment. However, we do not resile from our
March 2002 article on solar power.
Moving goal posts on the auto ammeter
Thank you for the magazine. It is much appreciated and read
from cover to cover when it arrives.
I noticed in the October 2002 Circuit Notebook pages a clamp
used in a DC auto tester and wonder if the same principal can be used in the
June 2002 ammeter. This would then enable the tester to be much more portable
and used in a commercial application. If so, would calibration settings still be
the same? Someone always wants to alter the goal posts, don't they?
Comment: yep, people are always moving the goal posts. In
principle, since both circuits used the same Hall Effect pickup, the clamp idea
should work with the June 2002 circuit. Wish we'd thought of it.
Amateur radio articles wanted
I would like to support the suggestions made by G. J. Wilson in
October's edition of SILICON CHIP, regarding radio-related articles. I realise that radio and scanning
related topics are not everyone's cup of tea. This has obviously been proven by
the demise of any related magazines as well as the lack of new people taking on
these hobbies, but if we all sit back and watch it happen it obviously will.
It is no secret that the Internet has taken the gloss away from
Amateur Radio. After all, what young person would want to endure the stress of
studying and sitting for an Amateur licence when they can just jump on the web
with only the most basic computer skills. And the cost involved now in
purchasing a scanner capable of being able to follow the trunking network for a
lot of people would be over the top.
But SILICON CHIP could from time to time run related articles. This could spark the
interest of people that previously had no knowledge of these hobbies or simply
had overlooked them. It could even rejuvenate interest in people that have long
ago sent their equipment to retirement into the back of the wardrobe. And
nothing can strike up interest like a review on some new piece of
P. R. Dawson,
VK5NCM, via email.
Comment: have a look at the article on the simple VHF FM/AM
radio in next month's issue
Placement of padder capacitors
I believe that Rodney Champness is largely correct in his
response to Stan Hood about placement of padder capacitors (page 85, October
2002 issue). Not only 'Radio & Hobbies' but also 'Radiotron Designer's
Handbook' generally put padders at the earthy end of the oscillator coil
secondary. They were also sometimes put at the top end of the coil but in such a
way that the grid capacitor was connected to the fixed tuning capacitor plates;
never as shown in the Tasma circuit.
I suspect that the reason was that it made dual (or more) wave
switching simpler because another set of contacts would have been needed for the
extra padder(s). I have a vague memory also that the early variable padders were
made in such a way that it was convenient to earth the adjustment screw side to
avoid capacitive disturbance during alignment.
The 'Colpitts' argument is really a bit of a red herring
because that circuit uses the capacitance divider to achieve the phase rotation
necessary for oscillation whereas the oscillator coil uses the transformer
action of the two windings to achieve that result.
The reason the Tasma circuit is so effective is that the full
voltage developed across the oscillator coil secondary is applied (via the grid
capacitor) to the grid of the mixer. Any other arrangement must result in a
(probably variable) voltage divider effect with the distinct possibility that
oscillation will be less reliable at the low-frequency end of the band.
In my early days, it was standard practice to replace the mixer
when 2FC could not be received although it was sometimes possible to postpone
the inevitable by tuning higher up to get the oscillator working and then
inching back to the desired lower frequency. Nobody that I knew then used the
Tasma trick as a cure.
Cable modems vulnerable in thunderstorms
As a cable modem user I am worried about the high incidence of
damage to cable modems caused by lightning strikes. I am told that the cable
system of Telsta Bigpond has no protection. During a recent mild electrical
storm in the Brisbane region, a very high percentage of cable modems were
I am hoping that in the near future somebody might publish a
device to add into the cable to prevent such incidences from happening.
Derek J. Gratz,
Comment: there are power boards with surge and phone line
protection (eg, DSE Cat M-7868 for $39.80) but these do not protect cable
modems. The only foolproof method of protection against lightning strikes is to
disconnect your computer and modem from the power and cable socket - otherwise
the modem is the meat in the sandwich.
Even if there is no direct hit on the lines, a distant lightning strike may
raise the earth potential of the exchange sufficiently high to cause a modem
breakdown when it is earthed locally via the mains. Of course, the computer
itself is also at risk.