# Voltage Divider Resistor Picker

Discussion in 'Electronic Design' started by Tim, Feb 17, 2006.

1. ### TimGuest

Hi,
There are 480,000 different combinations of standard 1% resistor values. If
you need 2.75 volts from a 5.00 volt reference, which of those 480,000 pairs
will give you the closest result?

For this example there are 9 resistor pairs that will get you to within
0.5%, but one resistor pair will get you within 0.15%. Only 1 out of 480,000
combinations is the best pair!!

The Best Pair II resistor calculator program will calculate and display the
twenty one best voltage divider resistor pairs, as well as the error
voltages, percent error, "Perfect R2" and "R Thevenin" values. Results can
be scaled to any decade of course.

BestPair has been upgraded to Best Pair II. If you are interested you can
http://www.velotec.com/BestPair.htm

Thanks for looking.

Cheers,
Tim
www.velotec.com

5. ### TimGuest

If you find you do not like it please take a closer look at BestPair II -->
http://www.velotec.com/BestPair.htm

In seven years BestPair I had ZERO unsatisfied users.

You get what you pay for.

Thanks for looking.

Cheers,
Tim
www.velotec.com

6. ### Rich GriseGuest

The number of times that I've had to select values from a range like
that, I've done it "by hand" with a spreadsheet. ;-)

Although, it would be kind of a fun programming project - maybe I'll put
up a "divider calculator" web page. ;-)

Cheers!
Rich

8. ### redbellyGuest

If they are 1% resistors, then NO pair will be within 0.15% !!!

Mark

9. ### Spehro PefhanyGuest

Typically 1% resistors are within 0.15% or so.

Nothing wrong with trying to get closer to the ideal values on analog
stuff.

Best regards,
Spehro Pefhany

10. ### The PhantomGuest

This isn't unqualifiedly true. Some pairs MAY be within 0.15%; some may not.
What you want to say is that there is no guarantee that any particular pair will
be within 0.15% when built with real 1% resistors.