Elliott Sound
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Beginners'
Guide to Electronics - Tools |
Copyright
2001 - Andrew Walmsley
(Edited by Rod Elliott -
ESP)
Page Updated 21 Mar 2001
An Amateur’s Guide to Making It
Work
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Contents
- Part 1
Introduction
From the editor (Rod E) - I have inserted
some of my own comments, which are identified by (rode) tacked
onto the end. Otherwise the article is almost untouched. Many thanks Andy
- A fine piece of work.
A Pursuit Indeed ...
Praise be to electronics. There can
be no finer and more honourable pursuit for the man with time on his hands
and at least some money to burn.
In theory it is an inexpensive, safe and
absorbing hobby with at least the potential for learning what all the pretty
little coloured tubes and cans of various shapes and sizes in the back
of the television are. Beyond this, you can wow the men and woo the
women with your worldly wise talk of linear power supplies, voltage and
current amplifiers, pi filters, power transistors and heat sink efficiency.
Such talk will eventually guarantee at least one, and possibly more, of
the following –
-
A seat in the pub when everyone else mysteriously
disappears two minutes into the conversation.
-
A slap round the side of the head.
-
A workshop full of ageing and dilapidated
electrical gear, most of which presents a really serious public health
hazard, that you've promised to repair free of charge for your family and
mates as soon as you find the time.
The gathering of broken electrical gear is a particular
one to watch out for. It has been suggested that the recent unexplained
disappearance of a number of electronics enthusiasts may have been caused
by dimensional instability in their workshops. The theory is that
the accumulation of such vast amounts of semi-deceased gear can force into
existence a temporal doorway into a world with lead fumes for an atmosphere.
This theory has yet to be proved and may be a load of old cobblers.
However, it always pays to be wary.
1.
It Helps to Have a Purpose
Adopting a (slightly) more serious note, the remainder
of this article will address some of the issues that you will need to be
aware of if you are coming into the field of electronics as an absolute
beginner. As with any activity there are some dangers, but the risk
of suffering any form of harm can be reduced to practically zero by adopting
a few simple working practices and taking a careful and methodical approach
to the work in hand.
On the upside, the rewards to be had when you have
learned enough to consider yourself a competent amateur are many and varied.
Its impossible to make an exhaustive list as everyone gets something different
out of their hobby. However, there are some general benefits and
these include ...
-
A deeper understanding and appreciation of the technology
that is a constant in modern life.
-
The ability to diagnose and repair simple faults in
your own equipment which would otherwise have to be professionally repaired
or replaced completely. As an example, an ageing hi-fi amp of mine
died recently whilst in use. Five minutes with the multimeter helped
me to confirm that the bridge rectifier in the power supply unit had failed.
In this case the repair cost me nothing as I had an equivalent bridge in
my parts drawer. Even if I'd had to buy one, it would have cost me
no more than two or three pounds sterling. Not bad if you consider
that binning the entire amp and replacing it with a new one of a similar
quality would have set me back about a hundred times the cost of the new
rectifier.
-
The satisfaction of correctly constructing kits and
designing and building your own circuitry.
-
The scope to acquire faulty electrical items at little
or no cost and restore the unit to working order in your own time.
I'm quite a fan of old audio/video equipment and you'd be amazed if I were
to tell you about all the lovely pieces of gear that I have seen destined
for the skip when the fault was nothing more serious than a tired transistor
or even a blown fuse. A good example of this is my own record deck
– a 1974 Bang and Olufsen Beogram 4000 which was going to be binned after
three "professional" repairers had failed to bring it back to life.
I picked the unit up for ten pounds sterling, spent half an hour replacing
the mains supply fuses in the case, and grinned broadly when I plugged
it in and watched it come to life. Its been used every day for three
years now and has worked reliably on all occasions. What's more,
it gives every indication of being quite happy about the prospect of running
perfectly for another 26 years, so long as it gets the occasional bit of
TLC. As an added bonus, when I want back and talked to the guy in
the shop where Id bought it, he was so pleased to hear the record deck
working that he gave me amplifier that went with it for nothing.
In the next section, we abandon our traditionally light-hearted
approach and discuss the very serious issue of electrical safety.
If you read nothing else at all in your life then this read this.
2.
Avoiding Evaporation Trauma
In the last section, I aimed to convince you of the
fun that you can have being an amateur sparky. If you find that you
don't fancy it at all then I suggest that you quit now before you start
buying loads of relatively expensive gear which will be of no use whatsoever
to you.
Electronics is usually a lot of fun, and I try to
reflect this in the light-hearted nature of these articles. However,
for this part of the series I'm afraid that I have to get very, very, very
serious about something.
Yep, you've guessed it – electricity.
In very basic terms, electricity is the flow of electrons
along a conductive material such as copper. In order to use electricity
in anger, this flow of electrons must be impeded by some sort of resistive
or capacitive load. This can be an electrical circuit of varying
complexity, a coil such as found in an electric motor, or a filament such
as found in a normal lightbulb. I accept that this is verging on
a gross over-simplification of the truth, but it will more than adequately
serve our purpose at present.
One of the characteristics of this flow of electrons
is that it will always follow the path of least resistance to the point
of lowest potential. Since the human body is around 98% water, and
given that water suitable saturated with mineral salts (that's us!) is
an excellent conductor of electricity, the potential for you to involuntarily
and unexpectedly become the conductor of a great deal of electricity is
considerable. For the amateur electronics enthusiast, this risk is
increased a hundredfold since your chosen hobby will inevitably bring you
into potentially intimate contact with electricity on a regular basis.
It seems to be an article of faith amongst many that
the lower the electrical voltage, the less potential danger exists when
working close to it. This is complete nonsense when you consider
that the static electricity shock that you can get by touching the body
of a car on a hot, dry day can be in the order of 30 – 50,000 volts.
Whilst such shocks can be irritating, it is extremely unlikely that you
will be inconvenienced beyond this due to the very, very low electrical
currents involved, and the instantaneous nature of the discharge from the
car body to your own. However, when working with direct current (DC) or
alternating current (AC) sources at much lower voltages, the result of
physical contact with a live wire can be almost instantaneous death.
Indeed, a current of 50mA (barely enough to make
a low wattage lamp even glow) is sufficient to send your heart into a state
called "ventricular fibrillation", where the heart muscles are all working
out of synchronisation with each other. Little or no blood is pumped,
and you will die within about 3 minutes unless help is immediately at hand.
Sometimes (but less often), your heart will simply
stop. If this happens, it is possible that with external heart massage
that it might re-start, and occasionally it might even re-start by itself
- rare, but it can happen.
However, worry not. As I have said, this risk
can be reduced considerably with the application of a few simple working
practices, a careful and methodical approach to the job, and a large helping
of simple common sense. The list below is intended to give some pointers
to what the correct working standards should be. What it is not is
the de facto standard for electrical safety. It is expected that
you will use the recommendations below in conjunction with the absolutely
basic principles such as not overloading plug points, not mixing electricity
with water, and not leaving live bare wires dangling within reach of anybody.
If you are still in the dark after reading the list
then I strongly suggest that you do not even consider proceeding with electronics
as a hobby until you have located and attended an approved course on all
aspects of electrical safety, and you are more than satisfied that your
understanding of the subject is correct and thorough. Many educational
institutions such as colleges and universities run such courses during
the evening. They are generally quite cheap to enrol on, and usually
run for one or two evenings a week for a period of five to six weeks.
-
Treat DC and AC electricity at ALL voltages with
the utmost respect and caution. This includes all household and battery
supplies, no matter how small the battery may be. Statistics suggest
that the survival rate for people with gunshot wounds is far higher than
for those who have suffered serious electrocution.
-
Unless you are ABSOLUTELY sure of what you are
doing, NEVER work on a live chassis under any circumstances.
Even experienced engineers are loathe to work on live equipment unless
it is absolutely necessary. Prior to working on any form of equipment,
ensure that it is isolated from the mains by physically disconnecting the
plug from the mains socket. If the mains socket is switched then
also ensure that you have switched the socket off. If you must work
in close proximity to any form of electrical socket then stick insulating
tape across the front of the socket to prevent electrocution due to tools
or fingers coming into inadvertent contact. In addition, take careful
note of what I say in all sections here before you even think about
breaking out the screwdrivers.
-
Never under any circumstances be tempted to "jerry
rig" your latest creation to the mains using bare wires and matchsticks
(or similar) shoved into a plug socket. You may laugh but I've seen
such suicidal stupidity perpetrated on many occasions. This is
an incredibly stupid thing to do ! When connecting any device to the
mains, use a good quality plug from a reputable manufacturer, and ensure
that the plug is correctly assembled and that all connections and covers
are secure and tight prior to connection. For plugs with integral
fuses, such as those supplied in the U.K., ensure that the fuse is of the
correct rating for the device.
-
Of course, there are rare situations where it is necessary
to work on a live chassis – setting the bias current on a power amplifier
is one example. Prior to commencing work of this type, it is IMPERATIVE
to satisfy yourself that ALL electrical connections are correctly
insulated in order to prevent accidental contact. This is particularly
important in equipment that you have built yourself, though I have seen
wiring in quite expensive commercial products which is nothing short of
reprehensible. When making insulated connections I have three sizes
of heatshrink sleeving. After ensuring that the connection is well
made and has no sharp edges which may puncture the sleeving, I alternately
apply and shrink each size of sleeving, finishing with the largest.
In this way, I am satisfied that there can be no accidental contact.
-
In addition to the other points raised above, NEVER
wear
a watch, ring, necklace or any other form of conductive jewellery whilst
working on electrical devices, whether they are live or not.
-
If, like me, you have switched mains sockets mounted
on your workbench, NEVER assume that the appliance that you are
working on is completely isolated from the mains when you switch the socket
off. To be safe, always completely remove the mains plug from the
socket and lay it well away from any live contacts in a place on the bench
where it cannot be knocked. In addition, give serious consideration
to having a qualified electrician install a residual current device (RCD*)
on the mains supply to your work room. These devices work on the
principle that if more current is flowing on one supply pole than the other,
then some must be going where it is not intended to. Under these
circumstances, the device will cut out the supply of electricity extremely
quickly. I have witnessed a situation where someone came into accidental
contact with a mains cable immediately after inadvertently slicing it in
two with a pair of hedge trimmers. Luckily, the cable was connected
to the distribution board via an RCD which cut out immediately, and the
unlucky gardener suffered no ill effects whatsoever. Had the circuit
been protected with a more traditional cartridge fuse, the situation may
have been far different. Even if a fuse does blow in a situation
where someone is being electrocuted (and this is not at all guaranteed),
this can take up to three seconds, which is more than long enough for the
unfortunate person to be killed outright.
-
Be aware of the fact that any equipment which utilises
power reservoirs such as capacitors in its design may well be live for
many hours or days after it has last been powered up. A excellent
example here is the power supply for any form of amplifier. Nearly
all power supplies for these devices utilise capacitance smoothing after
the rectifier, and in some cases the capacitors used can store a great
deal of power for a considerable length of time after the device has been
switched off and disconnected from the mains supply. When working
with equipment of this type, if you are in any doubt at all then it is
far safer to assume that there is power stored in the capacitors, and proceed
accordingly.
-
In addition to the points raised above, be aware of
the fact that ALL Cathode Ray Tubes in televisions, computer monitors
and oscilloscopes can store lethal levels of charge at many, many thousands
of volts for weeks after they have been switched off and disconnected from
the mains. The design, construction, repair and servicing of any
device incorporating CRTs is a very specialised and dangerous task unless
you know exactly what you are doing. Indeed, I know of many extremely
competent electronics enthusiasts who will not even consider touching devices
incorporating these components. To be safe, I suggest that you don't
either.
-
Microwave ovens have probably killed more technicians
than any other electronic device. The capacitor can store a huge electrical
charge, and this charge can remain poised to pounce on any unsuspecting
technician for weeks. These animals are seriously dangerous, and must be
treated with the utmost respect - or avoided altogether. (rode)
* RCDs are also known as earth (ground) leakage circuit
breakers (rode)
This may seem to be an extensive list, but I am loathe
to make an apology even if you feel that I may have overstressed the point.
Whilst I do find that the majority of people behave sensibly and apply
common sense when working with electricity, I have seen some inexcusable
examples of sheer stupidity in my time, and these have generally been as
a result of people not thinking about what they are doing. Mistakes
with electricity are at the best costly, and at the worst fatal.
In the next section, we make a thankful return to
slightly more light-hearted matters and discuss how to assemble a decent
toolkit without having to remortgage the kids.
3.
Tools, and Their Place in the World
Its always said that a bad workman always blames
his tools. A corollary of this is a good workman can only be as good
as the tools he is using. In this section, we'll look at the toolkit
you will need to assemble in order to get started as an electronics hobbyist.
Firstly, a word on the buying of tools in general.
I'm sure everyone who is reading this has strolled
around the odd Sunday market in the course of their lives and encountered
the mythical 50,000-piece toolkit of dubious geographical origin that cost
little more than a decent set of screwdrivers, and which seems to meet
all your needs in one fell swoop without breaking the bank. Whilst
these kits may seem to be excellent value on the face of it, and the tools
that they contain may look to be little different to their far more expensive
counterparts stocked by well-established retailers, they are generally
not up to the reasonably hard daily use to which you will put them in the
pursuit of your hobby.
In the case of tools such as hammers, spanners, screwdrivers
and drill bits, the very cheap ones are not only a waste of money as they
won't last two minutes, they are downright dangerous. Even when undertaking
very light duties in the workshop, you'd be surprised at the stresses and
strains on a tool as simple as the humble spanner or screwdriver.
In order to perform correctly under these conditions, good quality tools
are well designed for the job in hand, and the metal from which they are
made is correctly tempered and heat treated so that the tool will give
many years of trouble free service before a replacement is required.
Cheaper tools are generally poorer quality copies of the better designs,
and there is no guarantee that the metal has been correctly treated at
all. At the very least, such a tool may slip whilst in use and damage
the workpiece. At the worst the tool may bend, snap or even shatter
whilst in use, causing personal injury.
As a general rule of thumb, when buying tools you
should go to a well established retailer and only buy tools made by reputable
manufacturers. It is far better to spend some time saving up to buy
the best tools you can afford, rather than to compromise on cheaper ones
which will not last as long, and which may not be as satisfying to use.
This is particularly the case with tools that will be put to heavy use
such as hammers, spanners, pliers, screwdrivers, cutters and strippers.
When it comes to power tools, what I have said about
buying quality items is especially pertinent. It is important that
tools such as power drills, jigsaws, circular saws, routers and planers
are of good quality, and this extends not only to the tool itself, but
to any accessories or blades which are fitted to it. Be especially
wary of ultra-cheap power tools that seem to offer the world for little
money. They will not last long, they most certainly won't be up to
the job in hand, and you may end up completely spoiling what you are working
on for the want of something decent.
Before we start with our wish list, it's worthwhile
mentioning that there are very, very few injuries suffered when a well
designed tool of good quality is used correctly for its intended purpose.
The well known banged heads, scuffed elbows, skinned knuckles and puncture
wounds that give us the walking wounded of the DIY wars are only caused
when the right tool is used for the wrong job or a tool is forced beyond
its designed limits. Using the correct tool generally means that
you'll get the job finished quicker, you won't injure yourself, and you
won't break or spoil anything else whilst working.
-
Screwdrivers - The better quality screwdrivers
have tempered shafts and hardened tips so that they won't slip on the screw
head and damage the screw, the workpiece, or most importantly, you.
Try to aim to have at least four sizes of flat head screwdriver, and four
sizes of posidrive screwdriver, along with a decent set of flat headed
and posidrive jeweller's screwdrivers for dismantling or assembling smaller
components. For ease of use, those with the softer contoured handles
are far better than those with the traditionally shaped plastic or wooden
handles, and they generally provide far better insulation – this is a must
when working with electrical gear. You'll be surprised at just how
much use your screwdrivers will be put to, and how much it will hurt if
one slips, so buy the best that you can possibly afford.
.
In use, it is important to remember that a screwdriver
is only for the fixing and removal of screws. It is not a chisel,
a hammer, a crowbar, a counterweight, a hook, or any of the other things
that the many improvised uses I have seen may suggest. Years of experience
has taught me that screwdrivers are sentient beings in their own right.
If you misuse them they WILL bite back. Some day I'll get round to
publishing my extensive collection of scars to reinforce this point – there's
no teacher like pain :-)
-
Spanners - You won't need anything in the monkey
wrench league for electronics work. A good quality set of open ended
and ring spanners which go from 3mm to 13mm in 1mm increments will be ideal
for your purpose. If you're going to be restoring old equipment then it
may be an idea to get hold of similar-sized set of imperial spanners as
well, though these needn't be anywhere near the top of your list otherwise.
As usual, make sure that what you're buying is the best you can afford.
The drop forged chrome vanadium spanners from well-known manufacturers
such as Draper (in the U.K.) or Snap On (worldwide) are made to exacting
standards out of high quality materials. Whilst the initial outlay
from buying a set may have you sitting in a cool room for a while to recover,
they really will provide you with a lifetime of unfailing service.
In the U.K., cheap and nasty spanners are known as ‘knuckle f*****s’ -
nobody wants hands like an ageing prize fighter when you're trying to fiddle
that 2mm nut on in a space it's taken you the best part of two months to
get into.
-
Pliers and Cutters - Again, there's no need for
a pair of water pump pliers with 40 inch knurled vice grips. Try
to aim for a good quality set of pliers which consists of two or three
sizes of needle nosed pliers, a couple of sizes of flat nosed pliers, and
a couple of different configurations of wire cutter. As usual, look
for good quality well made examples with comfortable moulded grips that
provide high electrical resistance – this is very important. Cheap
and nasty pliers are particularly prone to shattering when being used with
enthusiasm. When they do give way, bits of razor sharp metal fly
everywhere at incredible speeds, so you're not even safe when standing
behind someone who's using a pair of bargain basement specials.
-
Knives - Frowned down upon by some enthusiasts,
but invaluable in my view. I have a set of scalpels for fine work,
a pair of Swiss Army knives for general use, and a couple of large lock
knives for stripping the insulation from heavy duty cables that won't fit
in my wire strippers. Do not even think about using something other than
a good quality lock knife when you're going to be applying some pressure
to the workpiece in order to cut through it – pen knife blades can simply
close against your fingers whilst in use. No further description
necessary I fancy.
.
The ubiquitous StanleyTM
knife is a good investment - avoid the many cheap copies, as they often
have a less than perfect locking mechanism. Searching the workshop floor
for the missing bit (prior to rushing off for microsurgery) is not the
ideal way to spend one's Sunday afternoon. (rode)
-
Hammers - There's nothing to be ashamed of –
even the most refined of us occasionally need to resort to the rough stuff
in order to finish the job. To be fair, it's rare that you'll ever
need a hammer when working with electronics, the two just don't go together.
However, having a small toffee hammer tucked away in the corner of your
toolkit can be invaluable, for example when working on racking or equipment
mounts. To be honest, it's so long since I bought a hammer that I
have no idea how to go about selecting the correct one. They used
to be sold by the weight of the head and I have two in my toolkit stamped
at six ounces and one pound respectively (roughly 170 and 220 grams).
If possible, try and get hold of a ball peen hammer with a head weight
of about 150 grams and a good quality wooden handle. For the use
that I suspect it will get, going broke buying it is not essential, but
remember to steer away from the really cheap and nasty stuff.
.
On the subject of hitting things, a set of centre
punches is essential if you intend drilling holes (which is hard to avoid
most of the time). A centre punch allows you to carefully mark a small
indentation on the workpiece before you start drilling, and it will stop
the drill bit from wandering all over the place until it finally decides
to make a hole in the wrong place. "Automatic" centre punches are also
available - these do the same thing, but you only need to press down on
the tool - a spring provides the tension, and a pressure sensitive release
"lets go" at the preset pressure and makes a nice little indent for you.
(rode)
-
Reading Lamp - What ? Nothing for nipping, gripping,
bending or knocking ? Nope, just a plain old reading lamp. Nowadays
reading lamps come in all shapes and sizes ranging from the standard old
anglepoise to space-aged low voltage halogen designs with the transformers
hidden inside an art-deco base. I would avoid the really expensive
models as I suspect you're paying a lot of money for design and styling
which will never be appreciated in the workshop. A simple flexible
necked reading lamp with a nice heavy base and a 40-60 watt bulb fitted
to it will be more than adequate for your needs.
.
While you are at it (especially for fine work, and
more so if you are getting old, like me :-) a good magnifying lamp or headband
magnifier is worth its weight in ruined circuit boards. (rode)
-
Drill and Drill Bits - Its a good idea to have
a large mains-powered drill for heavier work such as drilling metal casework,
and a smaller battery powered drill for lighter duty tasks such as working
with plastic, or drilling very small holes using bits which would be prone
to snapping if used in a power drill. In the case of both the battery
drill and the mains powered unit, if you can buy those that have electro-mechanical
devices which sense the pressure on the drill trigger and vary the motor
speed accordingly then all the better. This is an especially useful
feature on the battery-powered drill and means that you can work with very
delicate items at extremely low speed to minimise the risk of damage to
the workpiece. As usual, buy the best unit that you can afford from
a reputable manufacturer.
.
This is also true for the drill bits. It is
often more economical to buy these in a set and you should aim for good
quality items made from high speed steel. If you can buy a set of
drill bits which also includes one or two hand or power reamer bits then
this is ideal. Whilst all drill bits will eventually go blunt and need
replacing, the better quality ones do give much longer service than the
cheaper ones. When drilling any material, considerable friction is generated
between the drill bit and the workpiece. It is important that you
don't allow the bit to become too hot, as this can sometimes cause it to
soften and become ineffective.
During drilling, do not apply too much pressure to
the drill as you will almost certainly snap the bit. Over time, you
will develop a ‘feel’ for when the bit has nearly penetrated the bottom
of the hole, and you will know when to ease pressure on the drill in order
to avoid the jaws of the chuck coming into contact with the workpiece and
damaging the surface.
To extend the usefulness of your mains power drill,
you will also want to invest in a good quality drill stand and press.
Its probably a good idea to buy one made by the manufacturer of your drill
as you can then be sure that everything will fit together correctly.
If the drill press comes with an optional vice that attaches to the bed
of unit and allows workpieces to be held rigidly whilst drilling then all
the better.
-
Taps and Dies - Nope, not the ones on your bath,
mate. Once a suitably sized hole has been drilled in a piece of metal,
a tap is used to cut threads into the edges of the hole to admit and hold
a threaded fixing. A die is the exact opposite of a tap in that it
is screwed onto a shaft of metal (usually referred to as a ‘blank’) to
cut threads and make a bolt. There is a dizzying number of standards
in the world for specifying and cutting threads of different pitches in
different sized holes or blanks, and whole volumes have been written on
the subject. I don't propose to go into these at all here (though
the insomniac may find an excellent cure for his affliction within their
pages). In response to this multitude of standards, many tool suppliers
sell a kit of taps and dies covering the thread sizes and pitches that
will be most commonly encountered when working with mainstream equipment.
.
Taps come in a number of types but we're only really
interested in tapered taps which are normally used for cutting threads
in panels, and so-called ‘blind’ taps which are used for cutting threads
in holes which do not pass through the whole depth of the material.
A good example of the latter would be holes bored in one side of a heatsink
for transistor mounting bolts. When buying your kit, ensure that
it contains all the necessary sizes of tapered and blind taps. Using
taps and dies is nowhere near as easy as it first looks.
A detailed discussion is really beyond the scope
of this document, and it would be far better to find someone who is skilled
in their use and ask them to show you. Once you are satisfied that
you have mastered the basics, practise on some scrap metal until you are
sure of what you are doing. During the course of this learning process,
don't be at all discouraged if you turn out some dreadful examples.
As I have hinted, there is a definite knack to using these tools and time
is the best teacher.
-
Wire Strippers - These will separate the professional
amateurs from the amateur professionals every time. Unless you're
working with thick armoured cable, or very heavy duty solid core cable,
you're showing yourself up if you try and remove the insulation from the
wire with your thumb and the blade of a knife. Not only is it guaranteed
that you'll eventually slice a chunk of yourself off, but it requires an
incredibly light touch and almost a lifetime of practise to feel when the
blade has passed through the insulation and is about to damage the conductors.
In multi-cored cable such as mains cable, you can cut through the outer
insulator and damage the inner cable sheaths in one smooth movement.
Assuming that you even notice this potentially dangerous mistake, the only
thing to do is cut the whole lot off and start again. I'm sure that
if all the cable that this splapdash approach wastes each year were to
be put end to end then we'd be well on the way to the moon in no time.
.
If you're doing it right, you're going to be using
your wire strippers a hell of a lot in electronics. If you don't
splash out on any other tool in your kit, you'll be thanking yourself for
years if you show a little extravagance when buying this one. The
very best wire strippers are nicely balanced with padded handles, well
machined spring loaded mechanisms and replaceable blades. The standard
for wire sizes is called (not surprisingly) the Standard Wire Gauge (SWG).
All good wire strippers are marked in some way to indicate how the tool
should be set in order to strip the insulation from wire of a certain SWG.
If the tool is set to an SWG which is too high for the wire you are working
with, it will just damage and stretch the insulation without removing it.
If set too low, then both the insulation and some or all of the conductors
(assuming stranded wire) will be removed. If you are working with
solid core cable, the conductor may seem to be undamaged until you try
to solder it to the fitting, at which point it will snap. In all
cases, the damaged section of wire must be cut from the length, the tool
correctly set, and the operation repeated. If you have a serious
amount of disposable income to blow on a pair of wire strippers (and I
suggest that if you have then you should), you can buy some with an "intelligent"
spring loaded mechanism that "senses" when the blades have cut through
the insulation, and stops them before they reach the conductors.
The blades then move backwards in the jaw to break the newly cut insulation
away, all in one smooth movement. Its not necessary to set the SWG
for the wire that you're using, and they'll strip anything first time,
every time. Years ago, I went without beer for a whole month to buy
a pair of those – it was (damned) difficult at the time but I appreciate
my strength of will every time I use them.
-
Soldering Iron and Desolder Tool - You'll be
using your soldering iron almost as much as your wire strippers so it's
worthwhile getting a good one. Go to a shop where the assistant will
let you pick up a number of similar irons and chose the one that feels
comfortable and well-balanced. The heating element should be ceramic
cored and the iron should be designed in such a way as you can change the
tips as and when necessary. If you can select a model with low tip
leakage current then all the better. As well as the iron itself,
you'll need a good heavy stand, ideally with an integral sponge.
Its also a good idea to buy a number of different tips of varying sizes
for different types of work. The more advanced (and expensive) temperature
controlled soldering irons and soldering stations are overkill for the
beginner, though you may want to think about one if you're doing a lot
of work, or if you become very serious about your hobby.
.
Desolder tools come in a dizzying array of shapes
and sizes. For the hobbyist, the spring-loaded plunger design is
more than adequate. Be aware that these tools do need to be dismantled
and cleaned, practically after each session, and the tips and ‘O’ rings
do need to be replaced periodically. If you can buy a supply of ‘O’
rings and tips along with the desolder tool itself then all the better.
With regard to the solder itself, buy a decent quality
60/40 solder, and NEVER EVER use plumber's flux when working with
electronics. Its not necessary, makes a hell of a mess, and is highly
corrosive.
-
Files - Buy a good quality set of needle files
for close work, and a set of larger files for general metal working.
The now familiar caveat of buying good quality is still relevant even for
files. Cheap and nasty files have uncomfortable handles which will
do nothing but give you blisters and snap when you're using them.
The teeth are poorly machined and they'll just make a mess out of all your
hard work. A piece of metal worked properly with a good quality file
can sometimes not be distinguished from one which has been machined.
A couple of flat (preferably "bastard" cut), round and square files in
different sizes will allow you to make odd shaped holes for connectors
and switches.
-
Hacksaw(s) - A good quality full size hacksaw
and a "baby" version - but not the plastic bodied types - they are useless.
Cutting pot and switch shafts, reducing screws to a sensible length and
a multitude of other essential cutting tasks will be a lot harder if you
have to chew through them with your teeth. (rode)
-
Steel Rule - Absolutely invaluable this.
Buy a good one with both metric and imperial divisions. A couple
of cheap plastic rules will also come in handy. For marking out panels
before drilling, an accurate 90 degree square is a good investment.
-
Vice - Loose women ? Gambling ? Drinking to excess
? If you're already good at any of these then you don't need me to tell
you how to do them better, and if you've already got such a wild life then
when will you find time for electronics ? :-)
.
What I do mean is the humble old bench vice.
You don't need a huge engineer's vice for normal electronics work, a small
woodworker's vice will do just nicely. If you can get one that comes
equipped with a quick release mechanism so that you can move it to whichever
corner of the workbench takes your fancy then this is excellent.
One which will allow you to fashion and fit jaw covers made of wood or
plastic is also a good idea, as the standard cast or wrought iron jaws
will almost certainly damage a lot of the components that you will be working
with, no matter how careful you are.
On the subject of holding things in place, I also
find that a collection of artery forceps and a number of different sizes
of ‘G’ cramp are often just what you're looking when there just aren't
enough fingers or hands to go round. (Also see miscellaneous, below.)
Finally, for just a few of your hard-earned dollars
(pounds, shekels ….) you can get hold a tool with a heavy base, infinitely
flexible arms about six to ten inches in length ending in a pair of crocodile
clips, and with an integral magnifying glass attached. What's more,
they don't complain and drop the wire when it starts getting hot.
I don't know what they're called elsewhere, but they're commonly known
as ‘helping hands’ in the U.K., and they're the best thing since sliced
bread when it comes to connecting cables to small plugs or sockets.
You can arrange the cable and the socket just how you want and then apply
the soldering iron without fear of anything flying off into the distant
corners of the workbench. For example, if you chose to do a lot of work
with older hi-fi equipment as I do, you'll often encounter the old five
and seven pin DIN plugs and sockets. Don't even try to solder one
of these without a pair of helping hands.
-
Pop Rivet Gun - Whilst one of these isn't vital
for a beginner, they are useful. When actually installing the rivet
in the workpiece, you're asking a lot of the gun so buy a decent one, and
don't forget to maintain your stock of rivets and washers. The times
that I've gone to the rivet drawer to discover that I've used up the size
that I need are without number, and this always seems to happen on a Sunday
afternoon when everywhere is shut.
.
I can't resist a further word on the Sunday afternoon
phenomenon at this point. Whilst I have no proof of this (what would
you expect ?), I've a feeling that the forces of physics and the natural
vindictiveness of small inanimate objects are in a particular state of
harmony after about 2.00 PM on a Sunday afternoon. If it's a wet
and cold Sunday afternoon then this harmony is a particularly good one.
If it's snowing and you have a desperate need for the thing that you are
working on the next day then the harmony is practically angelic.
Expensive and difficult to obtain components that you could attach a spanner
to and happily swing from (on any other day of the week) will readily snap,
bend, run away after being dropped and magically metamorphose into something
the wrong size after 2.00 PM on a Sunday afternoon, and there's not a bloody
thing that you can do about it as everywhere is shut. To add insult
to injury, you just know that you haven't got a spare – you don't
have to even both looking, you just
know. I've talked to a lot of
hobbyists and mechanics who have built an entire belief system of uncanny
internal consistency around this phenomenon, to the point where they will
get very drunk on a Saturday night for the
sole purpose of averting
the temptation to do anything on a Sunday afternoon – it's nothing
to do with riotous quaffing or having a good time, it's all about avoiding
the Sunday afternoon sinking feeling - honest :-)
..
The above is slightly different in other countries
where a somewhat more liberal approach to regulated shopping hours is common
- the effect will simply perform an appropriate time shift to ensure maximum
annoyance and/or frustration. (rode)
-
Miscellaneous (rode) - Gripping
"things" - spring clamps, clothes pegs, G-cramps and a tiny (as in really
small) bench vice will be used once in a blue moon, or every day.
It is almost guaranteed that if you don't have a good selection of these
essentials, their immediate requirement to allow you to complete the job
will increase tenfold. Also include masking tape and rubber bands (the
former holds anything in place temporarily, and the latter are great for
keeping a pair of pliers closed on the workpiece :-)
.
Consider raiding your local medical supply outlet
for a pair (or two) of artery forceps. These used to be considered
“unusual”, but they are now available from many electronics retailers who
have finally realised the usefulness of these little devices. They
may be used as tiny pliers, clamped onto sensitive component leads to act
as a heatsink, or used to retrieve that (blessed) small screw from the
nether regions of a chassis where it has taken root. These are probably
my most used small “gripping tool” of all.
A large plastic kitchen cutting board can also be
very useful for cutting paper labels (to be stuck to front panels and covered
with clear plastic), plus other uses which will dawn on you when you see
all the knife marks on your workbench. Even slicing open plastic
packets of resistors or capacitors is made easier and safer if you have
a proper surface to do it on. Oh yes, add a couple of pairs of scissors
to the list while you are at it.
An array of pencils, a steel scriber, and a few permanent
and non-permanent felt tip pens will always be used, as well as a notepad.
I know I'm stating the obvious, but you'd be surprised how often these
basic essentials are nowhere to be seen.
Andy has made a good point with all
his suggestions about good quality tools, but sometimes the 50,000 piece
set for $29.99 actually makes good sense. Some of the tools will
break, but in the meantime, you have a huge array of things you can use
until you find out what you really need - you then replace the broken cheapie
with a good quality equivalent, knowing in advance that you will use it
(you must, otherwise you wouldn't have broken it, right?). Don't
trust any of the cheapie sets for anything other than "light duties" -
and sometimes some of the other bits of the kit can be modified into something
you really need, even for a single use job - a blowtorch, angle grinder
and hammer can modify almost any tool, and if you mess it up, you haven't
blown any serious money. This is a technique I have used many times,
and as a result have a very wide range of "interesting" tools (the original
purpose of which is now lost in time in many cases :-)
Earthed wrist strap and earthed mat for working on
static sensitive devices (e.g. MOSFETs and CMOS logic).
Insulating safety gloves for working on valve amps
and mains supplies. - Not to everyone's taste, but useful if you are sufficiently
paranoid (not a bad trait when electricity is involved).
Wirewool and fine emery paper for cleaning component
leads etc.
A first aid kit, especially if the workshop is away
from the house.
A self-contained smoke detector in case accidents
with the soldering iron etc.
A suitable brick wall (head-hitting for the use of)
for when things don't go quite right :-)
(With some additional input from
Geoff Moss, my unpaid, but very appreciated editor)
4.
‘Big’ Tools - Nice to Have Vs. Have to Have
We've now exhausted the list of smaller tools that
you'll need to make a start in electronics. As you progress, you'll
undoubtedly gather unto yourself a wide and varied selection of useful
tools above and beyond what I've mentioned in this section, and you'll
be amazed at just what you can buy. For example, I recently saw a
tool that you can fit to the end of your power drill that will make a four
inch deep perfectly square cutout of any size in any material short of
solid steel ! No more belting the hell out of a cold chisel just to fit
a socket in the wall I fancy !
Before we move onto setting up a workshop, it's worthwhile
briefly mentioning a number of tools which may not have an immediate application
to electronics, but which are often worth their weight in gold when carrying
out related work. Please remember to always wear the correct protective
equipment when using power tools. At the very least, always have
a pair of safety specs handy as a matter of course.
-
Drill Press - A small cheap drill press will
be more accurate than an expensive hand held drill, no matter how good
you are with the latter. For drilling heatsinks and even PCBs, they have
no equal. Most are now made in China and are a tad dubious, but if set
up with care will be more than adequate for most jobs where small or perfectly
vertical holes are essential. This is especially true if you are drilling
holes that are to be tapped. (rode)
-
High-Speed Rotary Engraver - These are made by
various manufacturers, and are invaluable for making small modifications
to cases, PCBs, and just about anything else that is not the shape you
want it to be. For a small tool, they are expensive, but add a few
sanding drums and disks to the basic set, and you have a tool that has
a multiplicity of uses for fine work. (rode)
-
Angle Grinder - Go anywhere, do anything, sharpen
anything and cut anything. Watch out for sparks and dust and ALWAYS
wear good safety specs. I've had the odd grinding disc explode on
me and it's NOT funny !
-
Circular Saw - Adds infinite macho appeal but
wear safety specs and please keep your fingers out of the way
-
Electric Plane - I can't imagine anything better
when wood refuses to fit !
-
Jig Saw - Just remember that they make different
saw bits for wood and metal. When cutting aluminium, always ensure
that the workpiece is well lubricated with light machine oil
-
Heat Gun - Great for mess-free paint stripping
and there's nothing better for heat shrink sleeving. Do try to remember
that these are not to be used as hair dryers :-)
-
Power Sander - For those times when you've got
better things to do than spend forever rubbing things down by hand.
Orbital sanders are excellent for fine finishing. Belt sanders are
particularly effective (and evil).
-
Band Saw - Excellent for case work, and a far
better alternative to a jig saw when making long cuts in sheet metal
-
Router - Can be used to cut perfect (including
recessed) holes for speaker mounting, and odd shaped cutouts for terminal
panels and the like. Rounding bits allow you to make all the sharp edges
go away on a speaker box, which is great for reducing refraction and protecting
small people from injury when they crash headlong into your cabinets. Other
router bits can make fancy trims or just simple slots for shelving or reinforced
cabinet assembly. (rode)
-
Sheet Metal Punches - Whilst not cheap, a set
of these useful little things will guarantee that you'll never bend or
break anything again whilst trying to force a 12mm HSS drill bit through
it at suicidal speed.
-
Welder - Of all electric arc welders, nothing
beats a MIG (Metal Inert Gas) set to my way of thinking. They’re
versatile, easy to use, cheap to run, and you can get some excellent results
with one after a bit of practise. If you're really going for it then
think about acquiring a small oxygen and acetylene welding set for metal
cutting, brazing and really fine welding work. When working with
electric arc welders, ALWAYS use an approved welding mask (there are NO
exceptions to this), and remember that a recently welded workpiece is guaranteed
to make you sizzle if you touch it, even when the bright red glow has gone
away!
.
With oxyacetylene equipment, bear in mind that both
gasses are HIGHLY explosive if incorrectly (or even correctly) fiddled
with. You won't just take out yourself and your workshop, you'll
very likely also take out the entire street (I'm not kidding here).
-
Lathe - Using one of these properly takes a lot
of mastering, but once you've got there, you can make practically anything
you need. Many hobbyists and home mechanics believe that the lathe
has almost totemic powers against the Sunday afternoon syndrome referred
to above.
-
Air Compressor - A tool of little use by itself,
unless you just want an unusual source of noise and heat. With the
right attachments, you can spray paint, blow swarf and dust out of the
hardest to reach places, and operate a whole array of air tools.
Not specifically something for the average home hobbyist, but one of these
really has some posing value.
4.
The Workshop
Okay, you're skint as a flint (i.e. completely broke!)
but replete with tools, and you're itching to get going. All that
you need now is the workshop.
In this section, I'll provide some guidelines on
how to establish a workshop, how to build a workbench, and how to store
components and tools so that what you need is always to hand without too
much searching and turning over of rocks. I'll also make a brief
mention of how to maintain your tools once they are installed and racked
up in the workshop, and how to approach your work correctly once the workshop
is in place and being used for its intended purpose.
-
The Right Place at the Right Time - The first
challenge is to select the place in your house, garage, outbuilding, shed,
shack or cave that will become your workshop. I know that your choice will
be limited by available buildings, space not dedicated to other uses, and
the overall size of your house and outbuildings, so consider the following
solely as guidelines.
-
Try to establish your workshop in a space no smaller
than 20 feet by 40 feet (around 6 metres by 12 metres give or take).
.
Naturally, your personal situation (or s/he who
must be obeyed) will dictate the feasibility of this - subtle force may
be required in extreme cases (i.e. every time). (rode)
-
Ideally, the space should be one that can be permanently
dedicated as a workshop. There's nothing worse than having to clear
all your tools and gear away in the middle of a half finished job.
In addition, the best way to avoid becoming cheesed off with the job in
hand is to know that you can walk away, close the door on it, and return
whenever you wish. Always remember that this will be your hobby, and that
it should always be fun and a form of relaxation and recreation, not a
chore. In some cases I've finished projects in a weekend when I've
been in the right mood. In other cases it's taken me six months to
a year to complete a piece of work, and I still have projects ongoing now
that I started years ago. Having a dedicated workshop allows me to
do pursue my hobby in this way.
-
The ideal floor covering for this space will be smooth
concrete with a coating of floor paint, or floorboards covered with hardboard
and linoleum, depending on the type of building. Carpet will inevitably
get stained, etched, burnt and dirty and dropped components have a knack
of disappearing into it forever.
-
Ensure that the space has an adequate source of ambient
lighting, ideally both natural and artificial, which you can then supplement
with your desk lamp for close work.
-
Ensure that there is a safe and reliable mains supply
to the workshop. I strongly suggest that where practical you take
a fused spur directly from the distribution board into the workshop board,
and feed each workshop socket from a separate RCD. There are different
types of RCD, some will tolerate a little more leakage or surge current
and take a little longer to trip, others are extremely sensitive and will
trip at the first sign of any form of current imbalance on the active and
neutral poles. Given the use to which the workshop will be put, always
go for the second type of RCD. Okay, this may seem a little over-cautious,
and will almost certainly not be cheap, but we're talking about a room
in which electricity will be played with on an almost continuous basis.
In comparison with the cost of a human life, a bit
of mains wiring and couple of RCDs is an infinitesimally small price to
pay. My own workshop is wired in exactly this way. I have of
course had the odd mishap over the years, and the majority were due to
unexpected component failure, and one or two have been due to working too
late into the night and getting tired, or just being bloody stupid.
In all cases my RCDs have protected me from any harm by tripping instantly,
and I've lived to tell the tale.
.
Where you must have
a temporary work space, portable "in-line" RCDs are available, and one
of these should be used as a matter of course. Also make sure that
you use the test facility that is provided on these units regularly, to
make sure that it is working properly - a false sense of security can get
you killed. Do try not to become a statistic! (rode)
On a final note, as is the case with all electrical
installations, if you're not absolutely certain of what you're doing
then for God's sake get the work carried out by a competent and correctly
qualified electrician. You can have all the safety devices in the
world, but if the wiring itself is a health hazard then you may as well
replace your RCDs and fuses with cut off lengths of six inch nails for
the good that they'll do you. Even if like me you're a relatively
competent amateur, have a correctly qualified electrician at least look
over all your wiring before you throw the switch for the first time.
If nothing else, at least you've then got peace of mind.
-
If the workshop will be in an outbuilding such as a
shed or detached garage, bear in mind that there will eventually be a fair
amount of expensive equipment stored in it, and secure the premises accordingly.
Your local police crime prevention unit can generally advise you about
how to go about securing your workshop, but common sense and a little low-grade
paranoia are just as good. It goes without saying that if there is
a window into the workshop then it should be covered by a net curtain,
and valuable items should not be left on display.
-
If you live in the U.K., or a country with a similar
climate (hard to imagine but there you go), you will need to think about
keeping the workshop dry and warm. If the workshop is in your house
then this isn't much of a problem. If you are working in an outbuilding
then ensure that it is free of leaks and draughts, and that condensation
is kept to a minimum all year round. Electricity and damp conditions
are not particularly good bedfellows, and keeping all your tools and components
in a damp and cold environment will do nothing at all to prolong their
life. As a secondary concern to the well-being of your tools, it's
a good idea if you can also be warm and comfortable whilst working, and
suitable heating should be arranged to ensure this.
.
-
The Workbench - The place where it will all happen.
I've spent many, many happy hours in front of my workbench and I attribute
a lot of these to the thought that I put in when building it. A good
way to start is to take your chosen workshop chair, sit down in it and
decide the height at which you will be comfortable working. Ensure
that your chosen height will allow you to keep your back and neck relatively
straight, and to work with your forearms at an angle of about ninety degrees
relative to your upper arms. Assuming the rough room dimensions referred
to in section 1, and the presence of a window in your chosen space, try
to run the workbench down the full length of one of the long walls as close
to the window as possible, and make it between a meter and a half and two
meters in width to give you plenty of space for your tools, your test equipment
and the project currently in hand. Where practical, support the workbench
on sturdy brackets anchored to a load-bearing wall with rawlplugs, or to
the wall frame rather than the cladding if the workshop is to be in a timber
framed building.
.
Supplement the brackets with a number of legs along
the front of the bench which should be securely anchored to the floor.
The top of the bench can be covered with thin aluminium sheet or heat-resistant
Formica, or you can do the whole job in one fell swoop by getting hold
of a suitably sized lump of kitchen worktop. This is an excellent
option if you don't want to mess around with Formica and evo-stick, or
if aluminium sheeting wouldn't exactly blend in with the room's existing
décor. Tools which will be permanently attached to the bench, such
as your band saw or drill press should be fitted within easy reach, but
away from the section that is to be your permanent working area.
Its a good idea to attach about eight mains sockets with double pole switches
and integral neon tell-tales to the top of the bench, and to feed these
from the RCD board that you can attach to the wall beside your bench.
Since you are now completely broke (as we established
earlier :-), good workbench tops are expensive! An alternative that
I have used (am still using, actually) is the "hollow core" interior door.
These are usually inexpensive, and are surprisingly strong because of the
cardboard matrix inside. Minimal bracing is needed (or none at all),
and they will happily support 1kW power amplifiers without a complaint.
Surface treatment is optional, since most are pre-painted with an undercoat
and they look quite good as well as being the cheapest worktop you will
ever get. Just don't drop heavy things on them, or the hardboard
surface will break. Not normally a problem - mine has moved
premises several times and has been in constant use for well over 15 years
with no protective covering at all ! They are not suitable for heavy
bench mounted tools such as drill presses, grinders or a vice, so don't
even think about it. (rode)
Storing tools is a fairly simple job, and you can
make an excellent rack with a decent sized sheet of MDF and a pot of assorted
self-tapping screws. There's the added bonus here that you can lay
everything out just as you want it without having to compromise as you
would with a shop-bought tool rack. Once you've decided what will
go where, use a pencil to trace the outline of the tool onto the MDF backboard.
It may all seem obvious when the tools are in the rack, but when they're
all out on the bench and it comes time to put them away, all you'll see
is an irregular matrix of random-sized self-tapping screws. If you
think this is the voice of experience speaking here then you'd be absolutely
right :-)
-
Storing Components - I've tried the lot – margarine
cartons, empty syrup tins, home made boxes, carefully sub-divided desk
drawers, cardboard boxes. You name it. In the end I had to bite the
bullet and buy a big metal rack containing many, many, many small clear
plastic drawers. I eventually expanded this installation to include
a couple of rails and about ten parts bins for the bigger items such as
motors, trannies and large capacitors. The whole lot cost me about
forty quid so it wasn't cheap, but now everything is correctly labelled
and I can find what I want when I want it. If you can find a cheaper
and more efficient way of storing components then by all means go ahead
and do it – this one works for me.
-
Looking After Your Tools and Yourself - This
is nowhere near as difficult as it may sound. Ensure that the things such
as knives and wire cutters which should be sharp stay sharp, and replace
items such as drill bits, files and screwdrivers as and when they become
blunt. Always use the right tool for the right job and remember that
if you are forcing a tool whilst grunting and sweating profusely with effort
then you're using the wrong tool, or the right tool in the wrong way.
Stop what you are doing immediately, take stock of the situation, and decide
on an alternative approach before either you or the workpiece are damaged.
.
The moving parts of tools such as pliers and wire
strippers do need to be lubricated from time to time. Use only a
small amount of light machine oil and lubricate only the linkages, not
the business end of the tool.
A good mental attitude in the workshop can make the
difference between a successfully completed project of which you are rightfully
proud, and an expensive piece of junk which you will have to bin.
If you watch a competent amateur or a trained profession at work, you'll
see a composed individual working calmly and methodically towards completion
of the task in hand. His work area will be well laid out and tidy,
and all tools will be carefully selected and correctly used. Only
commence work on your projects when you want to. Never rush to finish
a project and don't drive yourself unnecessarily. Remember that this
is a hobby – it should make you happy and enable you to relax and derive
reward from what you do. Before starting work, make sure that external
distractions are at a minimum, that the lighting is correct, and that you
are warm and comfortable.
Never work beyond your capabilities. If you
don't know what you are doing then stop immediately and use a suitable
source of information to learn what you need to know. You have to
be very lucky indeed for all your guesses to be correct ones when working
with electronics. More often than not the end result of an uninformed guess
is sparks, blown fuses, smoke, a nasty smell and a steep retrospective
learning curve.
Though the temptation when you're on a roll is to
keep working until you finish, don't become over tired as you will make
mistakes and you may end up ruining an expensive piece of equipment in
the process. Its far better to do a bit and then have a break than
to go for an all night bender in the hope that everything will go well
and the coffee won't unexpectedly dry up.
As a final note, if you like a couple of beers as
I do, don't attempt to do any work after imbibing. I once wired up
a guitar amp PSU whilst a little intoxicated, and I thought the standard
of my work was excellent. It was fortunate that I decided not to
throw the switch as a quick inspection the next morning showed badly routed
wires, missing or badly positioned insulation sleeving, and a pair of incorrectly
wired bridges – this is just why so many countries now have strict drink
driving laws. After a couple of beers you think you're doing fine
when what you're actually doing is making a right pig's ear out of the
whole thing.
And finally, why not go back and re-read section
2 on electrical safety ?
In the next instalment, we'll look at correct soldering
technique, and the right way to assemble circuits in general, I’ll then
complete the series (for now) with a short article on casing up your new
masterpiece safely and attractively.
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Notice. This article, including but not limited to all text and diagrams,
is the intellectual property of Andrew Walmsley and Rod Elliott, and is
Copyright 2001. Reproduction
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18 Mar 2001