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Saturday, 23 March 2013

Thinking In Terms of Current

Some years ago, there’s this movie called “Lost In Translation”, now, I have not watched it, but that reminded me of how I used to viewed or analyse circuit diagrams. During my early days – I cannot think or view the circuit in terms of current flow, as such everything being translated into voltage terms. Since DMM is handy for measuring circuit voltages – things looked good.
But as years goes by – when I got better in circuit understanding – I realize that by translating current into voltage (using resistance, impedance, equations), there are valuable circuit insights being lost in translation. For example – if you don’t think in terms of current flows – you cannot understand how decoupling works shown in previous posts:
To show you what I meant, from my earlier post about load line:
There is this BJT amplifier shown as below:
In this circuit – assuming that it is in linear region, collector current changes with base current directly, in fact Icollector = hfe * Ibase, where hfe is the current gain of BJT. Yes, Vout might be our parameter of interest, but it really is just a “byproduct” of this action: Vout = Vdd – (Ic * RC).
So for beginner – I would like to say when we view or analyse circuit – it is worth the effort to try to think in terms of current – it will open a whole new world.

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