Spintronics Community Forum

What new part(s) would you like the most?

We’re planning to make more types of spintronic parts and I’d love to know: What new part(s) would you like the most? It can be a variation of an existing part or an entirely new part. What would you find the most useful…or just fun?

A standard op-amp would be interesting. Perhaps something like a LM741. Just coming up with a mechanical version would be interesting.

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That certainly would be interesting! It would be a challenge - that’s for sure - but it would open up the wide world of op-amp circuits.

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How about a relay? It has to have continuous current running through it to remain active.


Ah, sure - unlike the transistor that needs constant voltage to remain active. It might be a little easier to use in digital logic as well: With spintronic transistors, you’ve always got to supply a path to let the gate charge drain out or it stays activated. I wonder how you’d make a mechanical relay like that. Any ideas?

Something like centrifugal governor can be a way to achieve that

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It would be cool to see an inverted transistor,
it’s just like a regular transistor, but it is on by default instead of off.

Another nice thing to have would just be an inverted diode as well.


I think a variable resistor would be great. It would add more customizability to circuits and provide an easy visualization for how changes in resistance effect circuit behavior


Technically the Transistor is already a variable resistor. (at least how it acts in the simulator)

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I think a toggle switch would be a valuable addition. Right now its really difficult to close one circuit and open another with the push of a single button. You can use two separate buttons, but then the closing and opening isn’t perfectly simultaneous, and there’s a possibility for user error where the circuit enters an unintended state with both buttons on or off at the same time. You can achieve it with a single button push if you use a transistor, but it’s unnecessarily complicated and suffers from leakage. So I would make a button with gears on the 1 and 3 levels (for maximum compatibility with the transistor) where pushing the button switches which gear is unlocked and which is unlocked so they are always opposite.


As a Computer Science major and electronics hobbyist, I’m interested in trying to build low-level computer components like RAM and ALUs! It would be cool to see some of the more advanced puzzles like the logic gates and rectifiers as “integrated circuits”, with the different sprocket levels corresponding to inputs and outputs. I just realised that an integrated rectifier is basically a bicycle crankset…

I have a few ideas that are particulary out there, though: How about a memristor, which changes its resistance over time? While a discrete memristor doesn’t really… exist, I can see a mechanical memristor based on a cam rider/floatvalve/similar that rises in and out of a sillicone oil reservoir. It could be useful not just for non-volatile memory, but it could act as a spin volt wave generator, too!

It would also be cool to have more ways of generating an output. The ammeter and capacitor’s volt meters are ingenious, and I can see ways they can both be expanded further: Perhaps ammeters with shaped ridges could produce specific waveforms (not unlike the old speak and spells/pullstring voiceboxes), which would be amazing for making “chip” tunes! spintunes? I feel like there’s a DJ joke to be made here somewhere.

Numerical displays of some sort would also be cool! The capacitor is a form of this already, but I think by leveraging the ingenuity of old fashioned mechanical displays: split flaps, counters, the (less old fashioned) flip-disk, there’s a lot of options to explore. Maybe even the ability to “modify” displays by swapping out the digits for any kind of glyph! The sky’s the limit with weird displays! Seismographs, so that we can make spin-oscilloscopes! A rack-and-pinion for representing a number line, or make an automatic slide rule! Heck, an Etch-a-Sketch with sprockets on the knobs! I’d better stop before I think of too many things to spend my money on.

I’ll close off with my last out-there idea: a Spintronics tile “chassis”- a small, wheeled platform which spintronics components can be placed on, with sprockets on the same level to steer it. I have no idea how many spin-volts would be needed to drive this thing, or if it would need an external battery of its own. I imagine a prototype could be made out of Lego, but I don’t have any Legos. Might be time to fire up my 3D printer…

Hope Spintronics is a massive success. It’s a home run in its charm alone!

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Yes! I think a variable resistor would be an excellent addition. I’m just not sure how to build a variable resistor in a cost-effective, compact way. Does anyone have any ideas?

Oh a toggle switch designed like that is a super clever idea. I like that. So the middle sprocket is the input and the top and bottom sprockets are either connected or disconnected from that middle sprocket depending on the position of the switch.

Wow, there are a lot of great ideas in there, @dther!
Integrated circuits: Yes! Absolutely. I bet they could be made with fewer parts mechanically than electronically, too. Which ICs would you want in mechanical form?
Memristor: Now that would be interesting in every way. It would diverge from regular electronics (but I mean, we’ve already gone there), and it would be super interesting to explore circuits that could be made with a memristor.
Outputs: Yup, I totally agree. I tried to make the ammeter play sounds at first, but it got overly complicated. I gave up for the time and just have it playing a tone. I would like to revisit it, though. I’m pretty sure it could work. I’m trying to think of other outputs that would be useful, too. Maybe a current meter that tells you the current quantitatively? Maybe a mechanical light (perhaps made using flint/sandpaper sparks)?
Numerical displays: I hadn’t thought of all those different types. I considered a straight up 7 segment display, but it would require a massive circuit to drive it. The other ideas you have there are simpler and clever.
Yeah, it would be cool to make a spintronic chassis. It would have to be fairly big to fit a circuit into it, but it would be the ultimate in steampunk. :slight_smile:
Thanks again, dther! Great ideas and lots to think about.


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Yeah, @Grande1900, the inverted transistor that is by default on instead of off is a good idea and probably not too hard to make. The reverse diode would be easy, too. I’m hesitant to make that one now, though, because it’s so easy to just put the diode on the outside of the chain to make it have the same effect as a reverse diode. That said, it’s not perfect solution, because sometimes you have to add an extra part in order to be able to put the diode on the outside of a chain loop.

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Not sure how the resistor currently functions but my initial idea would be increase normal force between two disks (one fixed one rotating) because the frictional force grows roughly linearly with normal force. You can get a normal force that varies linearly by compressing a spring attached to the fixed disk. All that would be left would be to figure out how to adjust the compression of the spring with a knob which seems feasible using some screw like mechanism.

While this is cost effective, I think it would run into one of the problems @pgboswell found in making the regular resistors- since, as mentioned, frictional force is proportional to normal force, that means that frictional force is also proportional to spin voltage, meaning that resistance would begin to drop linearly as voltage increases and vice versa.

The way resistors currently work is that they use shearing of silicone oil, a highly viscous newtonian fluid. What if there was a dial/plunger that raised or lowered the level of the oil, thus changing the amount of it in contact with the bearing surface? Keeping it watertight would be the main issue, but the mechanism for raising and lowering would be similar in complexity.

On ICs: the talk of Op-Amps above made me think of the 555 timer, but something tells me that would be either incredibly fun or nightmarishly difficult to design. For something less ambitious, it would be great to have ICs for signal processing, as that would create a wide range of interesting puzzles while relating to real-world educational topics, from RF to analog computing. I imagine a clock generator and wave generator would be quite simple and useful. With a bit of inspiration from old naval artillery computers, it might even be possible to make compact switch-programmable ROM chips, or even individual modules for basic analog computing arithmetic!

As for outputs: I had an idea for a Spintronic light, but with a bit of departure from pure mechanics- I imagined a gaslamp with a shade that could be raised or lowered, which would be very steampunk. Of course, an actual gas lamp would be comically unsafe for a children’s toy, so a more sane option would be a dynamo powered LED, which could either be wound up before hand, or perhaps even powered by the circuit itself, presenting an interesting challenge.

what if you used 2 magnetic planes that rotate wit a knob. at 0 they are parallel abd would have 0 resistance. when the knob is adjusted the magnetic flux begins to opose eatch other causing resistance to the driving mechanism.

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Function generator for more convenient alternating current