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 Forum index » DIY Hardware and Software » Developers' Corner
Gain and Offset
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Grumble



Joined: Nov 23, 2015
Posts: 1294
Location: Netherlands
Audio files: 30

PostPosted: Sun Nov 06, 2016 11:33 am    Post subject: Gain and Offset
Subject description: one opamp solution
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So I am in need of a module that lets me set the gain and at the same time set the offset.
Because e.g. sometimes I need a control voltage with a low amplitude added to an offset.
So I put this small device on a breadboard and it behaves surprisingly well.
I use a quad opamp, single supply that way the voltages are always between gnd and 5volt, so these output voltages will never destroy the inputs of my Arduino's.
I am using a MCP6284, from Microchip, single supply and an almost perfect rail to rail output of VSS + 15mV and VCC - 15mV !!
For every opamp there are two potmeters, one that controls the input votage and one that controls the offset. Mark that the offset potmeter is connected to -5 volt!.
The only drawback is that the input signal is inverted, which for a symmetrical signal (sine, square etc.)this is not a biggy, but for non symmetrical signals like an ADSR CV this might be a problem...


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m.o



Joined: Jul 05, 2014
Posts: 44
Location: Sweden

PostPosted: Wed Nov 09, 2016 4:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool!
Another variant would have been to control the gain by having a potentiometer instead of R7.
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