[sdiy] linearizing an exponential CV

[Roman Sowa]

Imagine typical transistor pair expo. Now instead of feeding the 
collector's current into integrator, treat it as your current input - 
put a resistor in there to have voltage input. Tie this collector to 
inverting input of additional opamp. What used to be your CV input is 
now a place to connect this additional opamp's output. And this will 
also be your new log output of the circuit.
So if you feed exponential volatage at the input, the result will be 
linear CV at the output.
This is typical log amplifier covered in literature since invention of 
the transistor.

Roman

W dniu 2021-01-12 o 23:06, Neil Harper pisze:
> hey everyone,
>
> i'd like to linearize a control voltage that rises exponentially. i'm
> familiar with how to do the opposite, taking a linear voltage and making
> it exponential (transistor pair expo converter or 2164), but I have no
> clue how to do the opposite.
>
> on paper I think I can take the exponential rising voltage, invert and
> offset it to get a falling log curve and then feed that thru an expo
> converter to get a falling linear curve. then I can invert and offset
> that linear curve to make it rising 0-5V. but that definitely doesn't
> sound like the most efficient way.
>
>
>
> -- 
> /// Neil Harper
> /// Every Wave is New Until it Breaks
>
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