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 Forum index » DIY Hardware and Software
Simple Offset/gain Circuit Schematic.
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Dave Kendall



Joined: May 26, 2007
Posts: 413
Location: England
Audio files: 3

PostPosted: Mon Jun 08, 2009 2:15 pm    Post subject: Simple Offset/gain Circuit Schematic.
Subject description: Basic, but useful.....
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Hi all.

Here's a dead-simple circuit I use all the time when tweaking circuits, and it is a useful module in its own right.

If built with both OFFSET and GAIN as centre detent pots, with both pots at 12 o'clock, there is no gain or offset - the signal, CV or audio goes straight through unchanged. The max gain with this circuit is 2X. It could easily be made more, by increasing the 200K resistor, but the pot would no longer be at unity gain at 12 o'clock.

The second pic shows how to convert Ken Stone's CGS04 mixer PCB, for those who don't like perfboard.
The trimmer version is useful for turning a 0V, +5V, +10V PITCH BEND CV from a midi to CV converter into a -5V, 0V, +5V output. (i.e. centred)
If using it for this, connecting the outer pins of the OFFSET trimmer to -Ve and GND gives more control range from the trimmer (because it needs to go negative anyway, so the trimmer only covers a span of 15V, rather than 30V.

If you're really enthusiastic, you could try wiring a resistor in series with each outer pin going to-Ve and GND, and use a smaller value trimmer. This would give even finer control.
Hope this is as useful to people as it has been for me. Smile


cheers,
Dave


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synthmonger



Joined: Nov 16, 2006
Posts: 578
Location: flada
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PostPosted: Mon Jun 08, 2009 3:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

No 2nd pic?
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Dave Kendall



Joined: May 26, 2007
Posts: 413
Location: England
Audio files: 3

PostPosted: Mon Jun 08, 2009 11:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Embarassed

here it is...

cheers,
Dave

(edited to actually include the pic Smile )


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Last edited by Dave Kendall on Mon Jun 08, 2009 11:39 pm; edited 1 time in total
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