10 Silicon chip Australia’s electronics magazine siliconchip.com.au
They were all mains-powered sets
and often required new power leads.
Our work was entirely unsupervised,
and we managed to avoid any casu-
alties.
I also had to spend a year in the ca-
dets. Before Camp, we were issued
with a 1919 .303 rifle which I took
home on the train. Security consisted
of putting the bolt in my bag rather
than in the rifle. Note that they didn’t
give us any ammo to take home.
There was a recent incident where
the Melbourne rail loop was shut down
for hours because someone thought a
busker had a rifle bag rather than his
instrument bag. Heavily armed police
swarmed the railway station. While I
believe the authorities had to do what
they did, there is something to be said
for “the good old days”.
Geoff Champion,
Mount Dandenong, Vic.Another request for multi-input audio
switcher
I was very interested to read your
excellent remote controlled preamp
design presented in the last couple of
issues. May I be selfish and suggest
another project that could draw on
parts of that design that would make
my home life easier?
I do not have a five-channel home
theatre set-up but instead, have a great
stereo set-up in my lounge room that
includes a slightly modified SC
power amplifier. But I have many
possible signal sources including
DVD/SAC, Blu-ray, Rune streamer/
DAC, TV, game console and even a
cassette deck.
Changing between these requires a
bit of fiddling with either the selector
on my preamp and/or another dodgy
four-way switch box. I have no prob-
lem with this, but it drives my family
crazy! A standalone six-input remote
selector based on that used in your
preamp would be a godsend. If it were
modular and scalable, I’m sure many
would find uses for it.
It would also reduce the amount of
eye rolling I get from my daughter. If
you really wanted to go to town, con-
trol via a phone or tablet would be
amazing, but I can imagine that would
be a bridge too far.
Concerning the complaint to NSW
Fair Trading about your mains-pow-
ered projects (mentioned in your April
editorial), if they pull you up for this,
then I hope they do the same to hard-ware stores. Take a stroll through their
electrical aisles. Surely they are also
promoting mains powered ‘projects’
with all the stuff they sell to DIYers
that can only be used by connection
to the mains.
At least you put lots of effort into
illustrating correct techniques and
warning of the dangers in your pro-
jects. I’m a long time reader of your
unique magazine and look forward to
every issue.
Kim Windsor,
Newport, Vic.
Response: as mentioned on page 6, we
are planning to offer a six-way input
switcher which can be used in com-
bination with the new preamp. Note
though that if you want to switch video
too, especially HDMI, you will prob-
ably need to use a commercial input
switcher. They are pretty cheap, but
it would be quite hard to incorporate
HDMI switching in a DIY project.Thanks for pointing out DDS module
flaw
I want to congratulate Ross Her-
bert of WA on tracking down the
cause of the DDS Signal Generator/IF
Alignment project (September 2017;
siliconchip.com.au/Article/10799)
failing to operate as designed (March
2019, Mailbag page 13).
The resistor array in my kit meas-
ured 1kW and replacing it with short
lengths of wire effected an immediate
response. I’m now using the DDS IF
Alignment unit to adjust a 1946 radio.
Robert Forbes,
Forest Hill, Vic.Medical alarms and the NBN
“Making emergency calls post-
NBN” in the March issue of Silicon
chip (Mailbag, page 10) really caught
my attention.
For about 17 years I co-owned the
VitalCall Medical Alarm business. I
am currently the Chair of Personal
Emergency Response Services Limited
(PERSL), an industry association rep-
resenting the interests of professional-
ly-monitored medical alarm suppliers,
service providers, and their clients.
Before the NBN, the PSTN was able
to operate for long periods during a
power failure and was extremely re-
liable, with a quoted 99.9% uptime.
It reliably supported a wide range of
socially important services such as se-
curity alarms, fire alarms, lift alarms
and medical alarms.