Advertising Index
Altronics.................................85-88
Ampec Technologies.................... 5
Dave Thompson........................ 111
Dick Smith Contest....................... 9
Digi-Key Electronics...................... 3
Emona Instruments.................. IBC
Jaycar.............................. IFC,53-60
Keith Rippon Kit Assembly....... 111
Lazer Security........................... 111
LD Electronics........................... 111
LEDsales................................... 111
Microchip Technology.................. 7
Mouser Electronics..................OBC
Ocean Controls............................. 6
PMD Way................................... 111
SC SMD Test Tweezers.............. 77
SC USB Cable Tester................ 105
Silicon Chip Binders.................. 51
Silicon Chip Subscriptions........ 11
Silicon Chip Shop............ 106-107
Silicon Chip RTV&H DVD......... 109
Switchmode Power Supplies....... 8
The Loudspeaker Kit.com.......... 95
Tronixlabs.................................. 111
Vintage Radio Repairs.............. 111
Wagner Electronics..................... 10
and a complete oversight on my part.
My question is, could this have been
the cause for all the output devices to
self-destruct? I have since connected
the Earth wire from the mains socket
to the power supply.
I think that, as the amp worked well
during my initial testing, it probably
doesn’t have any incorrectly placed
components or dry solder joints. I was
very meticulous in the soldering and
placing of components. Do you know
what might have gone wrong? (P. S.,
Mount Pleasant, SA)
● It is possible that not having the
mains Earth to the amplifier could
have caused the destruction, but it
seems a bit unlikely.
Have you checked what happens to
the output from the signal generator
when switching frequency? Does the
output initially clip on one half of the
cycle that could cause the amplifier
to have a DC offset for a short period,
which could cause an overload that
destroys the transistors? There is AC
coupling on the amplifier input, but it
may not be enough to save the amplifier if that happens.
You could check what happens
with no load on the amplifier, as that
shouldn’t cause the amplifier to blow
even if there is a significant DC pulse.
Modern car radio
antennas aren’t good
I have a 2018 Volkswagen with a
short 20cm roof-mounted aerial and
the radio is full of hash when driving
near railways and power lines. Is there
a better replacement aerial or accessory to improve reception? Would ferrite rings over the aerial make a difference? (M. P., Croydon, Vic)
● The problem is probably due to
Notes & Errata
SMD Trainer, December 2021: The parts list and kit for the SMD Trainer Board only
lists two 100nF capacitors when three are shown on the schematic and PCB. The
kit has been updated, but those who have already received kits should note that
the circuit will most likely work correctly without the 100nF capacitor below IC2.
Hummingbird Amplifier Module, December 2021: in Fig.7 on p23, the “E” & “B”
labels for Q12 have been swapped. In the body text of p23, MLJ15032/33 should
read MJE15032/33.
Pocket Weather Station, November 2021: in Fig.2 the DAT connection from the
DHT11 should connect to pin D4 of the Arduino Nano, not D5.
The February 2022 issue is due on sale in newsagents by Thursday, January
27th. Expect postal delivery of subscription copies in Australia between January
26th and February 11th.
112
Silicon Chip
Australia's electronics magazine
low-amplitude radio signals making their way to the radio’s antenna
input. This could be due to bad connections, especially if you live near
the sea. Make sure that all connections from the antenna to the radio
are clean and undamaged. This would
require removing the radio to check
the antenna connection at the rear and
also removing the antenna.
Any ferrite ring over the antenna
would likely reduce the antenna radio
reception and detune the antenna.
Alternatively, there may be a noise
source in the car itself. The ignition
can be the source of radio-frequency
(RF) noise with petrol engines,
although that is less of a problem
these days with plug-on-coil systems
that eliminate the spark plug leads.
The alternator could also cause noise
if the brushes are worn. Have those
aspects checked out if the problem
persists.
Unfortunately, most modern vehicles simply don’t have very good radio
reception because consumers don’t
want ugly, long aerials sticking out
of their cars. Many cars either have
a small ‘shark-fin’ antenna like yours
or use the rear demister element as
an antenna. Neither is all that great of
an antenna.
If you don’t care about the appearance, you could consider having a flexible whip-style antenna mounted adjacent to the bonnet or on the door frame.
Find a good installer who will route
the antenna wire neatly and take measures to prevent rusting, or you could
mount it yourself if you’re confident.
Identifying a
Silicon Chip PCB
I came across a circuit board
recently. I believe that it is a Silicon
Chip design and would be grateful if
you could tell me what it is used for.
The board has the label “SC 11410971
LIGHTS” on it. (G. H., Camden, NSW)
● You can look up PCB numbers on
our website at siliconchip.com.au/
Articles/ContentsSearch
Simply type the PCB code into
the “Kits / PCBs” field and click the
“Search” button. Searching for that
PCB number gives the following result:
October 1997: The Flickering Flame
For Stage Work (siliconchip.com.au/
Article/4790) by Ross Tester, kits:
Jaycar KC5234, PCBs: SC 11410971,
1 shop item
SC
siliconchip.com.au
