[sdiy] rectification/min/max question

[Derek Holzer]

A while back, I posted on the topic "Is this a comparator?". My problem 
is to only pass control voltages above a certain threshold. Several 
posters recommended either rectifying the signal, or using a Min or Max 
construction. This answers half the question, but not the other half.

When using a Max function, for example, with a threshold voltage of 2.5 
V, anything above 2.5 V will go through, but otherwise the output 
voltage will remain at 2.5 V. A rectifier would do the same, if I 
understand properly.

What if I knew that my signal had a dynamic range of 0-5 V, but I wanted 
anything under 2.5 V to equal zero, and anything over 2.5 V to scale 
from 0 - 2.5 V? Or ideally, it would scale from 0 - 5 V? I don't know 
that would be easier or more difficult...

So I guess the question is, how to remove the offset voltage? Invert the 
threshold voltage and add it to output?

And after that, how to regain the full 0 - 5 V range in the signal that 
is passed?

Thx + best,
Derek

-- 
derek holzer ::: http://www.umatic.nl ::: http://blog.myspace.com/macumbista
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