An electronics 'alphabet'

In a strange city, how would we find our way without a map?

In any electronic circuitry how would we find our way without a circuit diagram? As a matter of fact, even a rather simple device you'll find easier to build, to repair and even to understand how it works if you have such a circuit diagram. Let us find out how we can read such diagrams and make up our own.

Let us take the continuity tester from Fact Sheet No 5 as an example. You will remember the layout, here reprinted on the left.

If we now convert this to a circuit diagram by using the proper symbols and putting them together as a technical drawing. it looks like the one on the right.

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We can now follow the the path the electrons take and how they are manipulated by the various components they have to pass on the way. In this example both drawings are very similar. When things are getting more complicated, and the circuit board gets filled up with more and more components however, it becomes difficult to follow how it works. Then a circuit diagram becomes necessary. This diagram we can 'read' and understand how the gadget works.

You'll find it easy to learn the 'alphabet' of electronic circuit diagrams. It's just a matter of getting to know the symbols one by one and following the lines that represent the wiring inside the diagram. Crossing lines (in most drawings) are not connected. See below. Every dot put over crossing lines represent a soldering point. That is where wires are joined together.

For a start: A collection of symbols used in circuit diagrams.

You can draw any circuit diagram by hand. But then, it is nice when a circuit looks neat and professionally drawn on a computer and printed out. If you have the appropriate software it just takes a little time and care. Many drawing programs have the necessary tools and, in a special folder, you may even collect certain symbols for later use. You simply 'create' them, then name and save them in a (maybe a 'components'-) folder. Any time you can pull out the bits as you may need them in your circuit, paste them in and move them around until it represents the device you are working with.

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Often engineers and technical people talk about connecting this or that 'to EARTH'? What does it mean to 'earth' some equipment, or 'grounding it'? In our next Fact Sheet No 8 we will be 'earthing' ourselves. See you then.

If you have any questions or comments, please send them to my mail address.

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