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.

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



-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist