Often when designing analog circuitry you'll need to use a resistor divider to reduce a voltage by a certain ratio. The trick is finding two good resistors to do it. Guess and Check by hand is not a good option with the 1% values. So, out comes a bigger hammer, courtesy of Perl. I use this all the time, sometimes out at client sites, so I threw it up on the web.

Portions of the CGI code were liberally borrowed from Muhammad A Muquit's "upload.pl" application. All icky looking code is my own.

I find this tool extremely useful, you're welcome to it, but the ubiquitous use at your own risk caveats certainly apply here! I'd be interested to get bugs or improvements back. If you want to look at the code, do a right click on the links and chose the "save as" option. (at least with Firefox..)

So here are the tools:

Tool for chosing resistor values when you have a desired R1/R2 ratio: resratio.pl

Tool for chosing resistor values when you have a desired Rb/(Ra+Rb) ratio: res1divider.pl

Here is a table of 1% resistor values.