4 Silicon chip Australia’s electronics magazine siliconchip.com.au
GPS units may be affected
by week rollover
I have just become aware that the
GPS week number is a 10-bit value
and that it rolls over on April 6, 2019.
More information and a countdown
are at: https://www.gps.gov/
Winston Campbell,
Coonabarabran, NSW.
Comment: most newer receivers
should handle this OK. It will be in-
teresting to see whether anything fails
when this occurs.
Losing the ability to make
emergency phone calls
Thanks for publishing my letter on
making emergency phone calls post-
NBN in your March issue (pages 10 &
12). Following the major power failure
in Hornsby on February 13th & 14th,
I now have some first-hand answers
regarding the reliability of the mobile
phone network during a power outage.
The power failed around 12:15pm
on the 13th. Two and a half hours lat-
er, all the 3G carriers were off the air.
I asked my mobile phone to do a scan
of available carriers and it could only
find a very weak signal; too weak to
use. I cannot say if the 4G network was
also down at this time as my phone
does not support 4G.
I noticed one base station with a
mobile generator attached at around
6:45pm, so it is possible some carriers
came back on the air that afternoon.
A check at 6:30pm at Mt Kuringai
still showed no available 3G signals,
and I still couldn’t get 3G reception
at my home at 6am the following
morning.
So it seems that I can expect 3G
service for a maximum of three hours
after a disaster knocks the power out.
Our power was out for 18 hours, so for
15½ hours, we would have been un-
able to make 000 calls if connected to
the NBN by HFC.
I think that the NBN HFC rollout
needs to be stopped until a reliable
000 phone service is made available
during power cuts.
During this outage, my ‘old-fash-
ioned’ copper telephone service never
skipped a beat and was utterly reliable,
allowing us to ring people to find out
what was going on and when power
might be restored. Will we able to do
that once the NBN roll-out is com-
plete? I seriously doubt it.
David Williams,
Hornsby, NSW.Clipsal dimmer recommended
to cure flickering LEDs
Regarding the letter you published
titled “LED lights on dimmer flickerperiodically”, on page 97 of the March
2019 issue, I asked a couple of electri-
cal contractors how to solve this prob-
lem, which I was also having. They
recommend that I use a Clipsal univer-
sal dimmer, which is said to be better
than other similar dimmers and does
not suffer from the flickering problem.
And regarding the letter on failing
motor capacitors on page 14 of that
same issue (in the Mailbag section),
this is an everyday problem encoun-
tered with conventional fan and com-
pressor motors. It does not apply to
inverter-driven air conditioners which
use the inverter to drive three-phase
motors.
Peter Cave,
Ormiston, Qld.Other uses for Motion-Triggered
12V Switch
I wonder whether Nicholas Vinen
realises other uses for his Motion-
Triggered 12V Switch (February 2019;
siliconchip.com.au/Article/11410).
Here are two:
First, I wanted an entry light for
my motor camper side door, one that
turns off a few minutes after pressing
a button. Nicholas’ circuit is good for
this – just omit the vibration switch
S1! The switch S2 is at the entrance;
the LED light is the load.Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that
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