Turning a lowly .22 LR Case into a High-Tech Memristor

The .22 case design dates back over 150 years to 1845 when a Frenchman named Flobert invented the .22 CB cap. Some years later the case length was extended to make the .22 Short, then extended again to make the .22 Long and finally the load was modified to produce the .22 LR, 40 years after the original invention of the .22 CB cap. So what does this have to do with Memristors, and what the heck is a Memristor?

Memristors are the future of computing. They are a electrical component similar to a resistor, only their resistance increases or decreases, depending on polarity of a current passing through them. Imagine an incandescent light bulb (which are in fact resistors) that increases in brightness over time, but if you swap the polarity of the electrical connection it decreases in brightness over time. It is essentially storing a piece of data, the resistance.

What this means is that instead of 16 capacitors being used to store 2 bytes of data in memory, a single memristor could be used instead. Not only would this dramatically increase the amount of data that could be stored, speed up the time it takes to access memory and also save a lot of power, memristors do not lose their memory when the power is turned off. Hard drives and computer RAM could become one and the same, and be equally as fast. The commercialization of memristors will be as significant as the commercialization of the transistor.

So what does this have to do with .22 LR cartridges?

Well a clever guy at the EEVBlog forum developed a DIY memristor at home using a .22 LR case and Copper Sulfide. He coated the case with Copper Sulfide by filling it with sulphur and heating it until the sulphur had burnt away leaving a blackened brass case that had reacted with the sulphur. He then inserted a coil of wire into the case and soldered it onto the base (inside). He then soldered another piece of wire to the outside of the base. He then filled the case with epoxy.



I don’t know how this memristor works, and neither it seems does the inventor, but looking at the oscilloscope trace above, it is definitely a memristor. The only problem is that slowly over time this memristor loses its special properties and becomes a simple resistor. Still, its a good effort for a guy working in his garage using 1840s technology!

Guns and technology, my two favorite things.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Science!

    • Budogunner

      My only regret is that I can’t upvote you twice because of your avatar. As “Pinkie Pie” twice won awards for finding security vulnerabilities in Google products I find your post especially relevant.

  • Spencer

    As a computer engineer I find this stuff fascinating. For anyone curious about the subject I’d like to point out that currently some of the most interesting usages for memresistors being explored include faster and more robust solid state memory solutions, more efficient FPGAs(reprogramable computer chips), and various kinds of analog circuitry that require some kind of memory storage including chips designed to vastly improve artificial nueral network performance.

    • Porty1119

      I find it interesting how much in the way of cutting-edge computing seriously departs from ‘traditional’ digital hardware. This, vacuum transistors, et cetera,

      • JumpIf NotZero

        Even as an EE I don’t know how to reply to that.

        You might as well have said, I find it interesting no modern carbines takes clips or no new machine guns have hand cranks.

  • Fred Johnson

    Thanks to TFB, I now won’t act surprised, or ignorant, when someone smarter than me brings up the topic of memristors.

  • ghost

    I don’t talk about memristorstrating in polite company.

    • Budogunner

      One of my college professors was from China. He consistently pronounced computer “memory” as “mammories” during lectures. Quite scandalous, I dare say.

    • hikerguy

      Ohhhhhhhhhh..!!! I ‘m kind of slow and it took me a little bit. 🙂

  • anonymous

    What is this .22 LR you speak of?

    I remember my grandpa telling me that back in his day, .22 LR ammo was so plentiful and cheap that it was used for an activity called recreational plinking, as though the people of that era didn’t have to conserve ammo. But I always thought he was just making that stuff up.

  • Mystick

    Considering the first true production memsistors are coming online at absurd prices, this is an excellent example of how hacks can make things work on the cheap.

  • smartacus

    i think the .22Short came from the .22BB not .22CB