Beyond back-of- Techno Talk
the-envelope design
Mark Nelson
It’s in our genes. Some of us are innately attracted to pictures of cute kittens. Others cannot resist
buying new gadgets for their electronics man cave or lady cave or... no, I mustn’t get side tracked!
But don’t worry; buying clever new products doesn’t make you a bad person. Far from it – your brain
absorbs some of the intelligence of the smart kiddos who came up with these new ideas. Buying them
aids the economy and heaven knows, we can do with that.
S
o own up now; are you a
gadget freak like me? No? Then
you are exempted from reading
any more of this exuberance. Yes? Then
keep calm and carry on! Even though I
consider myself a fairly seasoned electronicist, I still cannot resist trying new
products, especially when they appear
to save both time and money. I also
cannot resist spreading the word when
I discover something new that might
interest you as well. In this case, it’s
a product that was ‘new’ in 2012, so
it’s not technically a novelty, but even
so, it might still be new to you, so no
harm done.
Ancient and modern
First, we need a bit of history to put this
innovation in context. Back in the Dark
Ages, even if the Venerable Bede did
not specifically mention it, we know
that people designed electronic circuits
on the back of envelopes. When they
were certain that their creation had a
fair chance of working, they knocked up
its physical realisation on perfboard –
a kind of resin-bonded-paper material,
drilled with loads of little holes in parallel rows. You can still buy perfboard,
although it’s now provided with solderable circles around each hole to anchor
the leads of inserted components.
Back in the 1950s and 60s, however,
the primitive perfboard sold then had no
such solder-friendly luxuries. Instead,
you placed the leads of your resistors,
capacitors and other components into a
hole and soldered them below the board
with a big gob of solder. Next, you applied power to your new creation, and
then found that it didn’t work.
The arrival of Veroboard (also known
as stripboard) made making prototype
circuits much easier, by adding parallel
copper tracks to perfboard. Components
could now be connected by these tracks,
which could be isolated by using a
hand-held ‘spot face cutter’ to interrupt a track at one of the holes and form
Practical Electronics | June | 2020
separate electrical nodes. Cheapskates
used a drill bit in a pin chuck, but this
often weakened the board.
It was Terry Fitzpatrick who had the
brainwave for this revolutionary product; and the patent application was made
in 1959 under the name of his employer ,
Vero Precision Engineering Ltd. Geoffrey
Verdon-Roe was the managing director
of this enterprising company and now
you can guess why he called it ‘Vero’.
Veroboard was undoubtedly a major
breakthrough, but many of the designs
made on it still didn’t work first time
around. The components that you soldered into place (and trimmed off the
leads) were still either difficult or impossible to reuse. There had to be a
better way.
Step change
The revolution arrived around 1970 with
the solderless breadboard, a specially
perforated block of plastic in which an
array of tiny metal spring clips below
the holes could hold and retain the
leads of components, jumper wires and
other items. Instead of soldering components, you now simply pressed them
into place, with the ability to ‘unplug’
them when things inevitably didn’t
work. Now you could rearrange them
at will, redesigning the circuit until it
jolly well did work.
One of the first breadboards in Britain
was called ‘S-DeC’, leading to arguments in electronic labs over whether
it should be called an ‘ess-deck’ or
an ‘ess-dee-cee’ (I never found out
which pronunciation was correct).
The Verobloc was a similar product
and what all of these offerings had in
common was a fearsome price. From
memory, they cost about £20 in the early 1970s, equivalent to £266 in today’s
money, so it’s little wonder that they
were beyond the reach of the average
hobbyist. Today, you can buy them for
under £1, although that money will
secure only a cheaply made example.
Getting to the point
Having used the breadboard to confirm
that your circuit now works, you need to
make a couple of prototypes for evaluation. The easiest way would be to use
a PCB that mimicked the exact size and
metrics of the breadboard that you used.
And that’s precisely what the PermaProto Board does (www.adafruit.com/
product/1609). It comes in three sizes
(full, half and quarter) and the platedthrough holes are in never-tarnish gold.
According to Adafruit, the white silkscreen on the upper side has the same
breadboard markings you’re familiar with, helping to make transferring
components easy. The underside has
the five-hole pad design that matches a
classic breadboard, with four power bus
lines on the sides, and no mask so you
can easily cut tracks when necessary.
The drill holes used are of 1.2mm diameter, so even parts with larger leads will
fit. For photos showing how to use the
boards, see: https://bit.ly/pe-jun20-ada
Tempted to try one out? Why not?
These boards are available from several
mainline distributors such as Farnell/
Element14 and are frequently cheaper
on Amazon and eBay. But beware when
comparing prices; these clever gizmos
come in packs of three but some sellers are splitting the packs to make them
look cheaper!
And I do concede that unlike the
breadboards that they emulate, they
are not cheap. Yes, good value for what
they are, but not cheap. You can of
course help yourself by optimising your
breadboard layout and squeezing the
components as close together as you
can. By doing this, you may be able to
squash your proof-of-concept circuitry
onto a half or quarter-size Perma-Proto
board, saving cost. Even better, as your
skills improve, maybe your designs will
work the first time around, making faffing around with breadboards and proto
boards unnecessary. After that, all you
will need is more backs of envelopes!
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