siliconchip.com.au Australia’s electronics magazine June 2019 13
first, I have to ascertain if that is the
only fault.
On face value, it would seem we
can both use these new batteries; they
cost roughly twice what I paid for
the SLA replacement 18 months ago.
However, further information would
reassure me.
David Morton,
Geeveston, Tas.
Up-rated inverter suggestion for
the UPS project
You used a Giandel inverter in
your UPS project (May-July 2018;
siliconchip.com.au/Series/323) ,
which I am yet to build.
When I went to the Giandel web-
site, I found that it was evasive on
details. Also, the prices were suspi-
ciously low for the specifications giv-
en. I also found some people on The-
BackShed forum complaining about
the build quality of Giandel inverters
(siliconchip.com.au/link/aaqb).
Are you planning on doing an up-
dated project, hopefully with options
for a higher power version? What
about using Jaycar Cat MI5718, rated
at 2200W?
I have had trouble starting my do-
mestic refrigerator and freezer from
other 12V and 24V inverters. I have
read several readers letters in Silicon
chip and understand that the problem
is the extremely high starting current
that the induction motors have.
I tried a severe test with the Jaycar
Cat MI5718 inverter. I turned both my
(130W) refrigerator and (90W) freezer
off and cabled them both through a
switch to the Jaycar inverter, which
was running without power saving,
to prevent the soft-start feature from
working.
When I turned the switch on, the
Jaycar inverter started both devices
at the same time, quiet as a mouse,
no complaints at all. You may be able
to patch into the remote control to be
able to start and stop the inverter, as
you have done with the 433 MHz re-
mote control mains switches.
I shall follow the project with in-
terest.
Patrick Berry,
Turramurra, NSW.
Response: we chose the Giandel in-
verter because its price was very good
for the specifications given, and we
have not had any trouble with it in
our testing.
Note that with our UPS, since it is
usually switching over to inverter pow-
er just after mains power has failed,
the devices are already running and
so their ‘inrush’ at switchover should
not be too severe.
The Jaycar unit you mention does
look very good, and given its specifica-
tions, the price is not unreasonable. It
is somewhat more expensive than the
one we used in our UPS project.
It probably wouldn’t be necessary to
figure out how to control that inverter
remotely since it has a power switch
which can be set permanently to on.
You could then rely on the inverter’s
under-voltage lockout feature to shut
it down when the battery is flat. And
the built-in solar charger is a really
nice feature.Individual responsibility is
an outdated concept
It was interesting to read that some-
one had felt your magazine was un-
safe, due to some projects being mains
powered (Editorial, April 2019). What
surprised me is that you seemed sur-
prised at the allegation.
Our country has a legal system now
in place where self-responsibility no
longer exists; the government believes
the average person is too stupid to be
allowed to do anything without con-
stant supervision, hence the Nanny
State.
No matter what the situation, if
something goes wrong then the im-
mediate action is to find out where
blame can be assigned, with zero ef-
fort, rather than putting effort into find-
ing remedies. It’s far more important
to sack someone because vengeance is
what matters.
Every passing day proves Douglas
Adams was a prophet.
Anon.Comments on letters in
the March issue
I wanted to comment on a few items
raised in the Mailbag section of recent
Silicon chip magazines, mainly letters
from the March 2019 issue.
Regarding LED lights which flicker
when used with a dimmer, I have had
this problem and so has one of my
friends. We tried a range of different
commercial dimmers, but it made no
difference which one I used. The LED
lights still flickered at times.
Regarding the Majestic loudspeaker
cabinet, you are right that loudspeaker
design is a much more complex sub-ject than it seems. I suggest that your
correspondent buys a copy of Vance
Dickason’s “Loudspeaker Design
Cookbook”. It’s fantastic.
There are also many loudspeaker
design computer programs available;
some free, some at low cost. I have
used them and they are also fantastic.
Regarding “Joseph Lucas is a mod-
ern hero” by Dave Dobeson; while we
can be smug about the early electrics in
cars compared to what we have now,
it is worth remembering that back in
the day, they started from scratch. To-
day’s automotive electronics is more
evolutionary and builds on decades
of experience.
Our ‘older’ vehicles do not use the
Kettering System but it served well in
millions of cars for many years and
also in aeroplanes. Yes, analog engine
management systems present many
hassles today, as do older, high-qual-
ity audio amplifiers/receivers, stoves
with electronic controls and similar
items where the IC’s are not available
anymore.
As for your editorial in that issue,
“We all deserve a right to repair”, I
couldn’t agree more. Independent
automotive workshops are having an
industry-wide battle about this at the
moment.
The ACCC has taken some action,
but I am not sure if it is broad enough
to satisfy the workshops’ needs. The
availability of expertise is a different
question and always will be – as it is
for any discipline.
Regarding Fred Wild’s comments on
the usefulness of an automotive Low
Coolant Alarm, it is an excellent idea.
The modern practice of using tempera-
ture warning lights or gauges does not
cover the situation where a water leak
leaves the temperature sensor in free
air, so it is reading almost no temper-
ature at all, even though the engine is
overheating.
Another good solution is to fit a
device like the “Engine Watchdog”
which uses a temperature sensor
clamped to the hottest part of the en-
gine block.
It is linked to a temperature display
and warning buzzer which can be set
to any particular temperature. It can
also be used to control additional cool-
ing fans etc. It is not dependent on the
presence of coolant so it could save
expensive repairs.
Ranald Grant,
Brisbane, Qld. SC