10 Silicon chip Australia’s electronics magazine siliconchip.com.au
But why does it have to be this way?
Surely, transmission consumes far
more power than reception.
So if the mains power has not been
restored within an hour, the wireless
network should only respond to the
000 emergency number and ignore
any normal calls. This would extend
the running time of the network con-
siderably and hopefully, mains pow-
er will be restored before the batteries
are exhausted.
The only changes that would be re-
quired are to upgrade the firmware of
the network and to make 000 the last
contact of the emergency calling ma-
chines.
George Ramsay,
Holland Park, Qld.
Comments: ultimately, all organisa-
tional failures can be blamed on man-
agement. But engineers (both aviation
and software) made poor decisions,
contributing to those two airliners
crashes.
It’s hard to believe how many mis-
takes were made. Read this article and
weep for the stupidity: siliconchip.
com.au/link/aaqc
Keep in mind that since Silicon
chip is an electronics-themed maga-
zine, our coverage of the Avalon air
show is slanted towards electronics
and technology. No doubt there were
impressive exhibits at the show which
we did not cover as they were not elec-
tronics-related.
Your idea of extending the time that
mobile networks can operate after a
widespread power outage is a good
one. We’re not sure if it such a system
has been implemented – we guess not.
However, it seems likely that in a
major disaster, the batteries would still
run out eventually. The problem is that
there are more mobile towers than ex-
changes, and they have less space for
batteries/generators.Yet another request for
more preamp inputs
I was thrilled to see the new preamp
project, with much-needed features
like remote (linear) volume control
and a true-bypass tone control sec-
tion, but what is this – only three in-
puts? To me seems to be a prime ex-
ample of “don’t spoil the ship for a
ha’p’orth of tar”.
I would be more inclined to build
this project if it had, say, four inputs.
Or even a few more. I can easily use
four inputs without having an over-the-top range of devices to connect in
my lounge.
I need at least inputs for CD/SACD
player, turntable preamp, TV, DVD/
Blu-ray and a spare for portable play-
ers such as iPods/computers/etc with-
out having to fumble around the back
of the unit.
Three inputs seem just so stingy.
I’m looking forward to a revised ver-
sion with more.
Geoff Wood,
Wellington, NZ.
Response: we are planning to expand
the number of inputs to six in a fu-
ture article.Electret microphone crystal set
works well
I built the crystal radio set using an
electret microphone as a detector that
you published in the Circuit Notebook
section of the February 2019 issue
(siliconchip.com.au/Article/11408).
It’s a bit of a rat’s nest on a breadboard,
but I became quite excited when it
burst into life earlier today.
I purchased the microphone cap-
sule, antenna coil and rod from Jay-
car. The tuning capacitor was salvaged
from an old AM/FM tuner module and
the earphone came from a Western
Electric tone phone (a gift from an in-
ternet friend in the USA).
I can pick up seven local stations
here in Brisbane, and 1116kHz 4BC
comes booming in during their day-
time power broadcast of around
17kW. The transmitter is at Nudgee
and I live in New Farm, about 15km
away. It’s a good result for such a ba-
sic lash-up!
Austin Hellier,
New Farm, Qld.NBN does not cater for
emergency calls
I am amazed that the Editor did
not add a footnote to the letter (David
Williams, April 2019) concerning the
loss of emergency phone calling on
the NBN.
It’s a good object lesson in keeping
technical matters out of the politi-
cal arena wherever possible. When
the NBN was first announced, a call-
er to ABC Melbourne’s morning pro-
gram highlighted this very aspect of
the NBN.
The presenter (a stand-in, not the
regular person), shut down the caller
brutally and dismissively. His bias in
not wanting to hear anything critical of