Stupid polarized capacitor tricks

And with enough reverse polarity ... phssst ... FOOMP ... you've got the OTP version with integrated audible and smellable feedback :-)

That's why it's called "stupid capacitor tricks" -- not because it's practical, but because it's kind of interesting and fun.

I had a professor who, while a grad. student at UT-Austin TA'd a lab course where they did all sorts of crazy projects -- he mentioned one where he had a student modify a VCR to record the entire AM broadcast band at once. Not very practical (since realistically a VCR doesn't have that great of dynamic range, so you're really only recording the stronger stations -- the weak ones are lost for good), but certainly fun. :-)

Tue. :-) But they can only blow up if you put enough power into them, right? Limit the power to the milliwatt range, shouldn't be a problem...

Feasible, but write operations would be sort of slow.

I think that high-K ceramic caps may have enough c-v hysteresis to be able to store data... maybe even multiple bits per cap, like some Flash memories.

Ceramic caps are certainly nonlinear enough to make parametric power amplifiers, and high-voltage nonlinear shock lines.

John

and temperature sensors :)

Cheers Terry

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Way back when AC power distribution was new, ca 1920, there was the problem of how to charge batteries off the AC line. One cheap homebrew gadget was the electrolytic rectifier, with one aluminum electrode, one lead electrode, and a water solution, calcium carbonate or borax or something, in a glass jar. The oxide film on the aluminum would form at one polarity, insulating the electrode, and be eaten away on opposite half-cycles. A home-made fruit-jar rectifier was good for an amp or two.

Which suggests one could make an aluminum-plate nonvolatile ram with millisecond write times, sub-ms read times, and a fair number of bits per sheet. Some nonlinear X-Y bit access mechanism would be necessary, of course. You could certainly do an aluminum-plate rotating hard drive that used electrolytic storage; optical readout might be nice.

Which reminds me of the electrolytic PCB bare-board tester I might build some day.

John

Well, core was in the ballpark of 10us, improving to better than 1us by the time of its demise... heck, I'd be quite pleased to get 10ms speeds for an electrolytic capacitor storage device.

I have Joerg's spectrum analyzer on my back burner, since he says it'll sell like hotcakes, and being the typical engineer that's a good enough business plan for me. :-)

I realize you're on the wrong end of California, but if you have any suggestions on cool stuff to visit in San Diego let me know -- I'll be there this weekend.

---Joel

Strain gauge.

The happiest place on earth: Tijuana!!

Joel Kolstad wrote: > I was reading a circuits book today that spent more time on the > construction and modeling of components than most do. When I came to > the section on regular old polarized electrolytic capacitors it > occurred to me that you just might be able to turn an electrolytic > capacitor into one bit of non-volatile memory by purposely applying > the correct or reverse polarity to form or remove the dielectric > ("write"), and then test for this (by checking to see if the cap > behaves more like a cap or a short :-) ) later ("read"). >

There are too many unknowns, e-caps are not exactly inexpensive or miniature, reliability lifetime may be questionable, read and write access will be relatively slow and power consuming. The idea seems to be similar to phase change memory with the alteration of a material characteristic.

Prototype devices switch 500 times faster and use less power

Scientists from IBM (Yorktown Heights, NY), Macronix (Hsinchu, Taiwan, R.O.C.), and Qimonda (San Jose, CA) have announced research results on phase-change memory (PCM)?which has the potential to be the successor to flash. The nonvolatile PCM prototype devices switched more than 500 times faster than flash while using less than one-half the power to write data. The device's cross-section is only 3 x 20 nm, smaller than flash can be built today.

"Forming" a capacitor, which means turning aluminum to aluminum oxide, is a rather slow process. Also it's vulnerable to decay with time and temperature.

Your basic old EPROM does a similar trick, but just by storing charges in teensy little isolated wells.

Seems like a bump on the end of a USB cable is all you need, sort of like those Ladybug RF power meters, or the new Agilent knockoffs.

I haven't spent much time in San Diego, but I've heard that the Hotel del Coronado is worth a look/stay, and that there are some battleships or carriers or something you can tour.

One of my customers, Cymer, is in San Diego, but when I visit them I mostly have to work (frownie.) They make something like 70% of the deep-UV eximer lasers that expose the world's supply of ICs, and we make the box that fires the MOPA laser chambers.

John

Yeah, it's theoretically doable, but kind of pointless. How about a J-K flip-flop using nothing but relays? ;-)

Cheers! Rich

There were "Elapsed time" sensors that were a small electroplating cell, where after some rated number of milliamp hours, the active metal got plated off one electrode and the voltage went up.

There are also electrochromic(sp?) displays that work by electroplating. Maybe you could combine the two and have a non-mechanical version of a dipswitch. Configuration memory you can read...

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Ha, I remember making one of those when I was a kid using a leaded pencil on flat material and then, laminated it with wires connected on the ends to the rest of the circuit.

You gotta love it! WORM. But he wanted non-volatile, and that WORM would also be VOM (Volatile Once Memory) :-) Ed

Some of them even do a wipe-file operation. Only two pins left after the plume has wafted off, so hackers cannot figure what was in the memory.

The only semiconductors made on a C-4 substrate? ;-)