ResRat


Introduction

When making circuit I am constantly using resistors matched by some ratio in some form or another, whether that be in an op-amp multiplier or a simple resisistive divider. When you have strange ratios such 5.95 I required for the LM399 testbench it can be hard to find standard values with a common ratio. There are online tools to tell you the best mixture of standard resistors to create a required resistance but none that I could find that will find a ratio or use a single resistor. This is much more use for me as I would much rather use a single resistor in my design than over-complicate a design with series and parallel combinations and I am almost always looking for ratios not specific resistances. To do this I have made an installable console command that will allow you to find the best ratio. You can get it from GitHub Here and install simply by:

    ./configure 
    make 
    make install 

What it does

ResRat is a simple interface allowing for input of a ratio which compares all common resistor series to see if there is a resistor ratio that matches and if not reports back the closest in each series as seen below.


Figure 1: Resrat simple use.

Command line arguments

ResRat has two command line arguments if you'd like to skip the input step for speed and instead pass it in the command or choose a specific resistor series.

    resrat -r *resistor ratio* -e *resistor series*

Figure 2: Resrat command line arguments use.