Erica Synths EDU DIY Dual VCA Eurorack Module Kit - Manual (Page 17)

more gain, the other a lot less. So for the same amount of base voltage there would be
very di
ff erent amounts of current flowing through each respective circuit – if it weren’t for
the emitter resistors and the voltages they create.
Now, since the potential amount of current on the right side is a lot higher, we’d expect to
see a significantly larger voltage at the emitter there. In reality though, both emitters will
just be a few mV apart. This is because the more the emitter voltage increases, the
smaller the di
ff erence between base and emitter becomes – reducing the transistor’s gain,
and thereby the collector current, in the process. And as we’ve seen before, a very small
reduction in base voltage can already give you a huge reduction in collector current. So
we are essentially turning the transistor’s gain against itself – the more gain the
transistor has, the stronger the negative feedback and the more the gain is reduced.
Conversely, if the transistor’s gain is rather weak to begin with, then the negative
feedback – and thereby the gain reduction – will be weaker as well. To illustrate this, I’ve
drawn up four di
ff erent plots here.
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