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61257Re: [beam] Memristor

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  • Richard Piotter
    Jan 6, 2014
      Made a little design progress. I have to leave soon, so I'll make this real quick...

      I think I have a viable PC board design that places 20 memristors in a module that would mimic a 40 pin DIP IC, both in size and pin configuration. It would fit PC boards, 40-pin sockets, and breadboards. I still need to do testing, and order parts, but it's looking good so far, as long as my actual experiments pass their tests.

      Wish me luck!

      Richard Piotter
      richfiles

      Begin forwarded message:
      > From: Richard Piotter <richfiles1@...>
      > Subject: Re: [beam] Memristor
      > Date: January 4, 2014 1:58:13 AM CST
      > To: beam@yahoogroups.com
      > Reply-To: beam@yahoogroups.com
      >
      > I found these two parts at McMaster Carr. $11.20 for 100 balls. I can go with 1/32 balls (0.79mm) or 5/64 balls (1.98mm). I think I will get the larger ones to start with, but I am seriously debating on the smaller ones. At less than half the diameter of the bigger one, there would be a significant reduction in size, potentially allowing for even greater density. The problem is that I don't know how the sulfide may affect things over time, or if it's wise for the pads to be so close.
      >
      > http://www.mcmaster.com/#34665k21/=q3lxcc 1/32" balls
      > http://www.mcmaster.com/#34665k25/=q3lxct 5/54" balls
      >
      > The other concern, is these are 2017 alloy, with a touch of copper. I don't know if that is good or bad for memristor applications, as no one to date has actually IDed the alloy of aluminum used in their experiments. I don't know if 1100 (over 99% aluminum) was used, or if an altogether different alloy was used.
      >
      > So, opinions... does the ultra tiny 1/32 balls make sense, or should I restrict myself to the larger 5/64 balls for experimentation, for now. As for electrical connection, I am still considering headers, though now i am kinda looking at 40 pin PATA-IDE style connectors, as the cables are pretty much available for free everywhere, thanks to SATA!
      >
      > I also considered a balancing network for each memristor. A resistor pad would be be across each memristor to create a limited maximum resistance. A resistor pad in series would set a minimum resistance. Not certain how necessary this will be. But I have certainly considered it. I have also considered a board with memristors tied to a common rail, which would very nearly double the memristor count compared to the pin count. A common system needs a split +/- voltage rail to work, or a virtual ground set between + and real ground to achieve the proper memristance effect. with both pins of a memristor brought out, you can achieve the memristance effect by simply reversing analog or logic states on each side.
      >
      > I am planning to make an actual PC board layout for this. It'll simplify assembly, ensure alignment, and mean It's repeatable by simply ordering more parts. What configuration would anyone else be interested in if I made a PC board layout that anyone could order from a PC board maker? Common connected memristors, or both leads brought out. Common doubles the memristor count, at the expense of needing +/- voltage rails (or to make ground half the total voltage and use the REAL ground as a negative voltage in relation to the other two voltages). Individual I/O results in fewer memristors or much more physical connectors, but is more flexible. I am personally opting for the individual lines option, but if there was demand for common lines, I might make a second board layout for it.
      >
      > Richard Piotter
      > richfiles
      >
      >
      >
      > Begin forwarded message:
      >> From: Richard Piotter <richfiles1@...>
      >> Subject: Re: [beam] Memristor
      >> Date: December 27, 2013 12:08:32 AM CST
      >> To: beam@yahoogroups.com
      >> Reply-To: beam@yahoogroups.com
      >>
      >> Glad to hear someone else sees the potential. Now I need to order parts... The rubber pad, the aluminum balls, better PC board material (the radio shack stuff is brittle... I want stuff that has strength and will flex instead of crack).
      >>
      >> Looks like the airsoft BBs are 6mm in diameter... A little bigger than I would like. I'll see if I can look at that welding supply source. If they can't help, then 6mm gap it is. I was hoping for about 2-3mm.
      >>
      >> I got a lot to do!
      >>
      >> Richard Piotter
      >> richfiles
      >>
      >>
      >> Begin forwarded message:
      >>> From: Martin McKee <martinjaymckee@...>
      >>> Subject: Re: [beam] Memristor
      >>> Date: December 26, 2013 11:45:23 PM CST
      >>> To: beam@yahoogroups.com
      >>> Reply-To: beam@yahoogroups.com
      >>>
      >>> It sounds good to me. As you say, it should be pretty repeatable. With that form of mechanical construction, the biggest area of uncertainty should, likely, be the creation of the sulfide layer which could, very likely, very within a fairly wide range given level of clean on the board, temperature, coating density, etc. But, it could definitely be a major improvement in uniformity; and, it's likely to be very strong. That would make it much easier to experiment with.
      >>>
      >>> Interesting,
      >>> Martin Jay McKee
      >>>
      >>>
      >>> On Thu, Dec 26, 2013 at 9:47 PM, Richard Piotter <richfiles1@...> wrote:
      >>>
      >>> So my previous assessment of the liquid conductive paint pen "seeping" through imperfections of the sulfide layer and bonding directly to the copper pad beneath seems to be confirmed after some dissection. I actually had a "dot" of silver paint that resists separation from the copper unless picked at with some effort.
      >>>
      >>> Long story short... Paint pen is a bust... :(
      >>>
      >>> Good news, is the most annoying motor line we produced at the old company I used to work at gave me a BRILLIANT idea! Back then, we made a motor driver that had triplets of MOSFETs held against a sil pad on a heat sink by a cross bar with rubber pads and screws threaded ingot eh bar from outside the heatsink. The idea I conceived falls back to the idea of using mechanical point contacts, but eliminates so many of the issues of the cobbled together bench top experiments that prevent hobby memristors from being actually... you know, useable for REAL world applications!
      >>>
      >>> http://richfiles.solarbotics.net/robots/MemristorAlBall.jpg
      >>>
      >>> To explain, I discovered aluminum balls are commonly available as airsoft BBs, as well as for use in welding applications. Ideally, one would construct a pair of PC boards, with pads that mirror one another in alignment corresponding to each memristor. You would drill several screw holes to evenly distribute tension across the boards. you would use a sheet of foam or rubber like material that is soft and compressible between the two boards. A hole would be punched in the foam corresponding to each memristor and each screw hole. The aluminum balls would be dropped into each hole corresponding to a memristor, and the top PCB would be screwed down onto the bottom PCB, sandwiching the aluminum balls and the foam/rubber layer between them. As the foam/rubber type material compresses, it will simultaneously secure the ball from vibration and shield the memristor surfaces front he environment. As the boar dis tightened, the ball should make a mechanical contact with the copper pad of the top board, and the Copper Sulfide layer of the bottom plate. This ought to form a stable AND protected Copper - Copper Sulfide - Aluminum Oxide - Aluminum junction... Our memristor.
      >>>
      >>> The technique remains 100% mechanical, but secures, protects, and maintains constant tension on all the junctions. By using a torque driver, one can even guarantee all screws have the same tension. This in combination with the uniform junction size, as defined by the small point of contact defined by the aluminum ball's actual point of contact, potentially leaves us with a UNIFORM manner of memristor construction, and possibly a uniform characteristic!
      >>>
      >>> So... Thoughts???
      >>>
      >>>
      >>>
      >>> Richard Piotter
      >>> richfiles
      >>>
      >>> Begin forwarded message:
      >>>> From: Richard Piotter <richfiles1@...>
      >>>> Subject: Re: [beam] Memristor
      >>>> Date: December 23, 2013 6:48:40 AM CST
      >>>> To: beam@yahoogroups.com
      >>>> Reply-To: beam@yahoogroups.com
      >>>>
      >>>> I think the focus so far has been using sulfur powder, seeing as it's readily available to hobbyists with no restrictions. There is less danger in it as well, considering the toxicity of said gas.
      >>>>
      >>>> I suspect my liquid circuit pen paint managed to find imperfections in the sulfide layer and seeped through them to the copper, thus explaining my approximate 50% short ratio. The ones that didn't, I'll have to experiment on, once I get the rest of my lab set up.
      >>>>
      >>>> Richard Piotter
      >>>> richfiles
      >>
      >>
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