The perils of an Techno Talk
enquiring mind...
Mark Nelson
...and of streaming channels that stop working and smart TVs that lose functionality when they fail to
update as expected. But it’s not all bad news and this month we have some good tidings regarding
lowish-cost gadgets for hands-on electronics constructors. There’s plenty to take in, so let’s crack on.
M
any of our character traits
are inherited, and ever since
birth I have suffered from an
over-enquiring mind (from my mother,
for what it’s worth). I am told that as a
toddler I used to scare the living daylights out of my parents by playing
with the aluminium studs that were
used to fasten the cuffs of a newly
bought shirt. My father would never
discard anything that might come in
handy (another attribute that I inherited), so they were left lying around.
No, I did not try eating the studs, but I
did make the technical discovery that
these studs were a perfect fit for the
round openings in 5A socket outlets
that were common in houses in those
days. It’s a miracle that I did not electrocute myself!
Electrical matters fascinated me at
that tender age – and they still do. I
always wanted to know how things
worked and why our family said ‘eyether’ but other people pronounced the
word ‘ee-ther’ (please don’t tell me it
doesn’t matter!). For me, everything
had to be consistent and logical (I know
what you’re thinking) and easy to understand. Many people are happy to
buy their DIY needs at B&Q, but that’s
not enough for me. I was unable to
rest easily until I discovered that the
firm’s founders were called Richard
Block and David Quayle. Enough of
the prelude, let’s move on now to
some practical electronics.
ROKA — or is it really RoKa?
Almost every reader of this magazine
uses ROKA connectors, but possibly
without using that name. More likely you call it a DC connector, barrel
connector or tip connector (the last
because many low-voltage DC power
supplies are provided with a dozen
or so ‘tips’ that fit the output cable).
Although these low-voltage power
connectors are a German design, they
are now used all over the world. In
the rest of Europe, they are widely
called ROKA or RoKa connectors, a
10
name that comes from the initials of
the Robert Karst electronics company
in Berlin, which was responsible for
either inventing or popularising them.
And popular they are, with at least
two dozen different sizes. As Wikipedia
laments, many appear quite similar to
each other, yet are not quite mechanically or electrically compatible. In
addition to a plethora of generic designs of these connectors, there are at
least two different national standards
— EIAJ in Japan and DIN in Germany,
as well as the JSBP connector used on
some laptop computers. That’s only to
be expected, however, if you recall the
old saying that runs, ‘We favour standardisation fervently; that’s precisely
why we support so many of them’!
Needless to say, there’s not even any
agreement on whether the centre pole
of these connectors should be positive
or negative, although older devices
tend to favour a negative centre pin
and newer ones are centre-positive.
Another rule of thumb is that consumer goods have a positive centre
pin, while professional gadgets, test
instruments and accessories for electric guitars opt for centre-negative.
Let’s get practical
OK, what do you do when you are given a Sony Walkman to test and it has
a barrel connector slenderer than you
have ever seen? Other than forking out
£30 for a no-name power supply that
claims to be fully compatible (even
though the photo suggests otherwise),
are you stumped? Not now, because
you can just head off to Amazon and
search for ‘Aceyoon DC Barrel Jack
Adapter’ (https://amzn.to/2AhIJhY).
This is a 38-piece set of DC power tips
in virtually every pattern known to
mankind. Each power connector tip
can plug into a standard 5.5 × 2.1mm
male connector and adapts a power
supply to all of the other 38 sizes. The
advertising indicates that it is intended
primarily for ‘road warriors’ (do people still use this 1980s expression?)
but of course it is equally useful in the
home or workshop. Priced at £12.98,
it’s hardly expensive and the quality
is impressive.
Another handy and affordable gadget
I bought recently was a tool for forming wire links and bending component
leads (eBay UK item 232645791410).
Yes, you can do this work without a
jig but if you are populating a large
PCB, it helps to use one of these plastic
tools to ensure every R and C fits the
holes drilled in the board. The price
is £6.95 with free postage, and I am
sure that the same tool can be found
elsewhere on eBay and other websites.
It reminds me of a similar plastic tool
that came free with this magazine as a
cover gift back in the 1970s or 1980s.
I think I still have mine somewhere,
but it was designed for those chunky
big components that we used half a
century ago!
IoT = Internet of Trouble?
No, it’s not just my opinion, nor do I
use any IoT gizmos. But it’s clear that
there’s trouble afoot for many people
who have either welcomed the Internet
of Things into their homes or else
are planning to join the smart-home
set in the future. That’s the clarion
warning coming from Scott Helme, a
security researcher, entrepreneur and
international speaker specialising in
hacking and encryption. The problem
concerns a specific kind of security
certificate (the ‘root certificate’) that
authenticates websites that you or
your network connect to. These can
expire, leaving you none the wiser,
with negative consequences. Some
users have found streaming channels
no longer working and payment processors having problems too. If you
use smart appliances, I encourage you
to read his webpage at: https://bit.ly/
pa-sep20-rca – but if that leaves you
as baffled as I am, you can read much
more accessible assessments on other
webpages at: https://bit.ly/pe-sep20-ssl
and https://bit.ly/pe-sep20-reg
Practical Electronics | September | 2020
