Coming up in Silicon Chip
Subtractive Manufacturing
Dr David Maddison details the history of manufacturing techniques involving
devices like mills and lathes, through the early years of numerical control and
onto the amazing modern CNC machines. These can create a wide array of
shapes out of solid blocks of metal, timber, plastics or other materials with extreme
precision and virtually no human labour. He also explains quite a few other modern
subtractive manufacturing techniques that you may not be aware of.
Touchscreen RCL Box
This handy device fits into a compact Jiffy box and puts 43 resistance values,
19 capacitance values and 11 inductance values at your fingertips. It can even
step through a range of values by itself, to make testing and prototyping really
easy for you. Plus it displays the characteristic frequency of various RC, LC and
RL combinations.
Advertising Index
Altronics...............................75-78
Ampec Technologies................. 67
Control Devices..................... OBC
Dave Thompson...................... 111
Digi-Key Electronics.................... 3
Emona Instruments................. IBC
Hare & Forbes............................. 7
Jaycar............................ IFC,53-60
Keith Rippon Kit Assembly...... 111
RTL-SDR dongles with inbuilt upconverters
LD Electronics......................... 111
Following on from the article in this issue, Jim Rowe examines two low-cost offthe-shelf SDRs with inbuilt upconverters. They claim to give significantly better
performance than the smaller and cheaper dongles which use the “direct sampling”
approach, described in this issue.
LEACH PCB Assembly............... 5
Tektronics T-130 ‘Elcee’ Meter
Ocean Controls........................... 8
An in-depth look at the operation and restoration of a classic piece of vintage test
equipment. This was one of the devices that helped make Tektronics famous. It
used some ingenious principles to give extremely accurate and stable inductance
and capacitance measurements, with a very clever arrangement of thermionic
valves, wafer switches and passive components.
RayMing PCB & Assembly........ 10
LEDsales................................. 111
Microchip Technology.................. 9
Silicon Chip Back Issues.......... 81
Silicon Chip PDFs.................... 95
Silicon Chip Shop...........108-109
Note: these features are planned or are in preparation and should appear
within the next few issues of Silicon Chip.
The June 2020 issue is due on sale in newsagents by Thursday, May 28th.
Expect postal delivery of subscription copies in Australia between May 26th
and June 12th.
Philips TV using another HDMI cable.
This was our “spare TV” and about 18
months old but with very few hours on
it. All seemed well, so I turned down
the volume and left it running, confident that if the fault appeared, I would
hear the noise.
About an hour later, I discovered
that the Philips TV was completely
dead, without even the standby light
on. Investigations showed that the
power supply was delivering all the
voltages expected if the TV was in
standby, but it could not be roused
from that state.
The circuit is basically a tuner, power supply and a megapin IC that seems
to be everything else required to make
a TV work. As I wasn’t watching when
it died, I am not sure if there was any
unusual display, but I am confident
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Silicon Chip
that the PVR ‘bricked’ the TV via the
HDMI.
An internet search showed several
people saying that an HDMI connection had damaged their TV, but in nearly every case, there was a reply from
a tech ‘guru’ telling them that they
are wrong, that HDMI cannot damage
your equipment. I am not so sure now.
I replaced the Topfield with a Panasonic PVR, which can do a lot more,
and the problems with the TV have
stopped. So am I right in thinking that
a faulty device with an HDMI output can damage a television? (B. T.,
Bonogin, Qld)
• It sounds like your PVR had a fault
which was not only interfering with
its own operation, but was also delivering voltages to the HDMI cable outside of the normal range. These have
Australia’s electronics magazine
Silicon Chip Special Offer........ 35
The Loudspeaker Kit.com........... 6
Vintage Radio Repairs............ 111
Wagner Electronics................... 99
confused/damaged the TV(s) via their
inputs. Probably your Kogan TV has
better protection on the HDMI inputs
than the older Philips TV.
You probably aren’t surprised to find
out that many of these internet ‘gurus’
think that they know a lot more than
they actually do! Unless the connection is galvanically isolated (eg, optically or via transformers), there is always the possibility of damaging voltages travelling from one device to another. We’ve even seen a USB battery
pack fail and ‘brick’ a charger.
Replacing the PVR was a good idea.
It may be possible to repair the old
one, but probably not economically.
And you risk damaging more TV inputs if you go to test it, thinking you
have fixed it, and you haven’t. So we’d
leave it well alone and move on. SC
siliconchip.com.au
