Oversampling by any other name is just as slow.

Building an IV plotter from an Arduino Nano - Table of Contents

If you’ve given my current/voltage tracer a try, you may have noticed that it is very slow. It is slow because of the oversampling, and the oversampling is all that lets it work at all given the extremely simplistic hardware.

In honor of the slow speed of the IV tracer, I’ve decided to rename it “Rodriguez.”

If you’ve ever seen any “Looney Tunes” cartoons, then there’s a good chance you’ve seen Speedy Gonzalez. Speedy is “the fastest mouse in all Mexico.” If you’ve watched way too many Looney Tunes cartoons (as I have,) then you know that Speedy has a cousin named Slowpoke Rodriguez. Slowpoke is the slowest mouse in all Mexico.

I’ve renamed my IV tracer to Rodriguez because it’s the slowest IV tracer in all of Germany (and probably in all the world.)

Slowpoke (the mouse) is slow - he walks slow and he talks slow. He is, however, very clever. Slowpoke (the IV tracer) traces slowly, but it uses cleverness to beat the limitations of its hardware.

I combined the Arduino code and the Python code into one repository, and removed the old repositories.

The new Rodriguez repository is here.

Besides renaming the project and program, I’ve also fixed the base current bug and changed the background from black to white.

IV charts are usually printed out and load lines are drawn across the curves as part of the amplifier design process. A black background looks good on screen, but horrible on paper - and it wastes ink/toner besides.

This is a plot of a 2N2222 transistor made with the current version of Rodriguez:

2N2222 IV trace
2N2222 IV trace

White background, proper base currents in the legend.

I’ve still got a lot to do, but not tonight.

By the way:

I checked with the folks on the Electrical Engineering Stackexchange. Those little curlicues in the lower left corner of the traces are for real, and they are indeed negative. It turns out that they are even predicted by the normal models used to simulate transistors - LTspice shows them as well, though only as straight lines rather than the fancy curlicues that Rodriguez produces.

Building an IV plotter from an Arduino Nano - Table of Contents