>
> On Nov 8, 2008, at 9:01 PM, Forrest W Christian wrote:
>
> Michael Algernon wrote:
>> My customer wants to program a variable current load on his
>> batteries.  I don't know why ......
>>
> Is this a one-off?   If so, he/you might want to seriously consider  
> one
> of the electronic loads I mentioned in a previous posting to the list.

He wants 20 of them.

> I also found a couple of circuits which were similar to the one I was
> talking about...  The one which is best described is:
>
> http://electronicdesign.com/Articles/ArticleID/4056/4056.html
>
> The schematic is at http://electronicdesign.com/Files/29/4056/Figure_01.gif
>
> What I was suggesting is to hook your ADC up to the + terminal instead
> of using the pots as the voltage divider.  The general idea can be  
> used
> for constant voltage as well.....  As long as you can produce a  
> voltage
> on the - terminal of the opamp which corresponds to the actual current
> or voltage on the output, and put the desired matching voltage on  
> the +
> terminal, the load will "seek" to the current or voltage, since the
> opamp wants it's inputs to match....  If you increase the voltage on  
> the
> + terminal, it will increase the output voltage until the voltage  
> coming
> off of the current sense resistors matches.
>
> -forrest
>
>
>


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