MOTM

According to the Musical Engineer's Handbook (Bernie Hutchins, 1975), 3a 
(10), "The purpose of the resistor is to compensate for the offset due 
to the current that actually flows into the other input."  It is 
important to use in precision DC summing circuits.  The MEH also tells 
how to calculate the value.  I've wondered how important this resistor 
is in an inverting summer.  I don't know the answers to question #2.

Richard Brewster
http://pugix.com


Paul Schreiber wrote:
>
>
> Correct, not critical, 15K to 33K will work, 5% ok.
>  
> Bonus: what is the specific *purpose* of this resistor, and ...
> Bonus #2: what "bad effect" results from using it (but is compensated 
> for later in the design, and what is THAT compensation?)
>  
> Paul S.
>  
>
>     ----- Original Message -----
>     *From:* Miguel Mendoza <mailto:miguel@...>
>     *To:* motm@yahoogroups.com <mailto:motm@yahoogroups.com>
>     *Sent:* Saturday, August 01, 2009 5:58 PM
>     *Subject:* [motm] Missing resistor
>
>     Hi group, I'm starting to build a MOTM 300 kit that I was keeping
>     on a shelf and I'm missing the 22K resistor for R49. I'd like to
>     ask if any of you know if I can replace this one by other value
>     and what range or if this is a critical value. I have many
>     other resistors and I would like to finish mounting the oscillator
>     on this weekend...
>      
>     Thanks!
>      
>     Miguel.
>      
>      
>
>
>
> 
>
>
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