Erica Synths EDU DIY Dual VCA Eurorack Module Kit - Manual (Page 6)

VOLTAGE DIVIDER CLOSE-UP
In that analogy, we’d think of electricity as water flowing through a system of pipes,
with voltage being pressure and current being the flow amount per second .
Resistors would then be narrowings in the pipes, restricting the flow. 4
With this in mind, it should become clearer how our
voltage divider works. Because now imagine we apply
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a steady amount of pressure to the top here. Since our
system is wide open at the bottom, we’ll see water
flowing downwards. How much? That directly depends
on how narrow our pipes get, as this is quite literally the
bottleneck in this scenario. To make our lives a little
easier, let’s quantify things. We’ll say that both our
narrowings are exactly equal in diameter: 1 cm.
Individually, they’d let the same amount of water pass
through in this setup: 10 ml per second. But placed in
series, that amount would be slashed in half, giving us a
flow of just 5 ml per second.
So it’s fair to say that
there is some unused potential here – the two
narrowings are basically handicapping each other .
I like to think of it like this. If we were to bypass the
second narrowing, we’d suddenly see a flow of 10 ml.
This is simply because we got rid of the additional
bottleneck. Now the question is: where does this
unused potential go when there’s no bypass available?
The answer is simple: nowhere. It just stays in the
middle, between our two narrowings, as pressure. How
much?
Well, since the full realized potential is a flow
of 10 ml, but we see just half of that – the remaining
pressure is exactly half the pressure we apply up
top
.
Knowing this, we can derive what happens when we change the relation between these
two narrowings. If we make the bottom one wider, we’ll see two things happen: first, the
total amount of flow will increase. Second, the amount of pressure in the middle will
decrease. This is because we partly de-handicap the upper narrowing, which allows for
Read more about resistors in the components & concepts appendix (page 33). Also, please note 4
that the way I use water as a metaphor here might very well be nonsense, physically speaking. It’s
just a clarification crutch that has been quite e ff ective for me.
You can try this chapter’s concepts in a circuit simulator. I’ve already set them up for you right 5
here: https://tinyurl.com/y8dbcu2q – you can change all values by double clicking on
components.
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