[sdiy] Precision voltage offset

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At 2:05 PM -0800 01/25/02, GothGeek Sysadmin wrote:
>
>> So you want to add a negative voltage to another voltage??  Do you know
>> excactly how much voltage you need to add??
>
>Having not done much with CV yet, I was planning to just measure this when
>the time came to set the offset.  But calculating it looks to be 0.417
>>volts. I may have trouble getting the precision voltage source that I
>like >to use on a Saturday unless I can cross it to an NTE part and buy it
>from >Frys. I hate Frys.

Well, if it's .417 volts I doubt you could calculate that with two fixed
resistors, but with a trimpot set as a rheostat going from the negative
rail to the inverting input you should be able to set a fairly precise
offset.

I've gave up trying to buy electronic parts over the counter years ago.  I
order from Digikey and Mouser.  There is also Allied and Newark.

>I have a feeling the best way to do with is just by hacking the 8x5x code
>in the MidiCV box since Paia supplies full source, but I need the
>>experience trying to cook this up analog.

I'm no computer scientist, but building a simple op-amp circuit has to be
easier than hacking code!!