Let's get 'connected'.

In Fact Sheet No 5 we examined how you can build a simple, but useful test instrument. We put several components together on a board. Do you remember that we said: make sure the connections are tight?

How do you shake hands? Well, I don't really want to talk about shaking hands. However, shaking hands gives us a good idea of what we mean by 'connections'. Some people, when they shake hands, do not make a firm contact with you. Rather, they just hold their hand in your direction and sort of touch. By contrast, others shake hands with a reasonably firm grip.

This gives you an idea when you put together or repair electrical or electronic gear. Whenever you connect two conductors, say, two wires, or maybe the terminal screws inside a switch, or you solder components in, instead of just touching, the contact must be firm, in other words, the connections have to be secure.

What made me to write a Fact Sheet that deals especially with connections?

A bad connection can give you trouble.

And more trouble.

And more trouble still!

Aim for clean connections, firmly (but not over-) tightened!

Take the cable of an electric heater as an example. If the technician who does the work makes sure that the copper wires inside the power plug are clean and the screws hold the wire firm, and with enough contact area (because the heater uses quite a lot of current) then everything is fine. HOWEVER, if the handshake is just touching, or even sloppy (sorry, what I meant to say is:) if the connections are not tight, or the wire is dirty or corroded, the plug might get hot. In the worst case it gets so hot it could even set your house on fire.

See what I mean by 'trouble'?

Now let us talk about soldering. Some people say soldering is an art. Consider this: just one bad soldering joint can make an even expensive device useless. A 'cold' soldering joint (they are usually called 'cold joints') is usually intermittent. That means, ever so often when you are trying to fix the device, the fault appears, then disappears and there is nothing you can do to find and fix it. Everything works nicely. Put the equipment back into service and a few hours later the fault reappears and you can start all over again. In fact, you can go around-the-circle in this way for a long time.

It is not easy to teach soldering by correspondence. Ideal is finding someone who is really good at it and willing to give hands-on instructions.

Another source of trouble is switches. If not well designed they can wear out and also make some gear useless.

Modern equipment is reliable. That is because in factories engineers and supervisors are very aware that faults in their products give them a bad reputation. They make sure every connection is as good as can be. Even then, plugs and sockets have to be kept clean and in good order or ­ remember what I said about 'trouble'?

* * *

If you write a letter to a friend, you'll need pen and paper - and letters and words. If you wish to send your circuit to a friend, you'll need an electronic 'alphabet and sentences'. We'll talk about that in our next Fact Sheet No 7.

And once again, should you have any questions or comments you are welcome to send them to my mail address.

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Copyright © 1997-2010 Peter Schmedding, Child Development Projects, Canberra, Australia.