# The basics of Electronics

Electronics, The introduction

I have decided to do a page on electronics as (a) we all have electronics to thank that we are talking and (b) no-one else has done a page on electronics.

Electronics, The health warning.

There is a property of electronics that has to be taken into consideration when designing circuits, this is the fact that electronics only work once perfectly. This means that circuits can work perfectly once for a very long time or, more frustratingly, work perfectly once during prototyping, then an adjustment is made which makes the circuit work not quite as well as before, so you try and put back to the original setting but that only makes it worse. So you adjust the circuit more to make it work, but by now it's completely dead and ultimately has to be thrown away.
This can cause untold amounts of stress as I have found out during the two years of my degree in Electrical/Electronic Engineering. To elevate the stress of electronics I suggest you stop what you are doing take a few deep breaths. . . and then go to the pub. I am being totally serious about this if you don't believe my try it your self.

Electronics, the basics.

It must be stated first that current FLOWS and voltage is a measure of electrical PRESSURE.

The behaviour of electronics can be described with some basic rules, these are sometimes called first principles the three most used are:

Kirchoff's current law (KCL). This law states that the current coming out of a node (i.e. a junction) is equal to the sum of the current coming in to a junction.
So. . . Sum of current coming out of a node
= Sum of current going into the node.

Kirchoff's voltage law (KVL). This states that the voltage dropped across devices, e.g. Resistors, is equal to the voltage applied to the circuit.
So. . . Sum of applied voltage
= Sum of voltage dropped around the circuit (or potential difference (p.d.)).

Ohm's law. This law states that the voltage in the circuit is proportional to the product of resistance and current.
So. . . V (voltage) = I (current) * R (resistance).
Using transposition both current and resistance can be found if you know the other two variables.

Electronics, the basics, the conclusion.

So now you have had a introduction to electronics and you have decided that you can put up with all the setbacks this field of engineering throws at you can ask me questions about engineering as a general subject area of more advanced questions about electronics. If I can't help you then I will try and point you in the right direction. I intend to post more detailed and advanced entries soon or on request.

NOTE: (added 15/03/2001) the real laws explaind in this artical are misleading, check the edited artical for the correct explainations. I am leaving the originals here for posterity.