However there's a weird little caveat -- some papers attribute the piezoelectric effect to organic collagen fibers. Others attribute it to the inorganic component (apatite). In the end this paper seemed to have a reasonable measurement process so I've just ignored the exact cause of the piezoelectricity for the moment. From their tests, orientation of the bone is highly important.
They use an applied voltage of 100V then amplify (100db). I'm reasonably competent working with moderate voltages, but would prefer to try something under 30v as a matter of convenience (e.g. what I can reach with a DC-DC boost converter).
Normally though, I just hook up a crystal oscillator to a hex inverter @5V or to an MCU with some caps. I'm not entirely sure how I'd build an equivalent circuit at 30V! Doing unnatural things with crystal oscillators hasn't really come up much in my studies or career.
With some finagling, I believe ATMegas with the Arduino bootloader can be programmed using straight serial - you just have to time the reset pulse carefully.
I don’t think you can use it as an actual AVR programmer for new bootloaders, fuses etc. though. You need a full MCU for that. If you have a spare Arduino or ATMega that is happy, you can use ‘Arduino as ISP’ to do it.
Even on the equipment where you do get a graph of efficiency vs load, the line usually only starts at 10% load - that’s where your 70% efficiency figure is for.
As noted, at 0% load efficiency is by definition 0%.
Assuming that this is a 10MHz reference, at the extreme your reference is 0.003Hz off from nominal (3e-10, or 0.3ppb error). It varies by 0.08ppb in the plot. IDK what it is that you bought (TCXO, OCXO, whatever), but that's rather impressive stability. Depending on what type of oscillator it is you can expect a temperature coefficient anywhere in the several ppm to 0.1ppb. Do you know by how much the ambient temperature (or even better, the oscillator temperature) changed over the duration of the plot? I don't work with temperature-compensated oscillators very often, but I don't see an issue here.
i assume its measured under laboratory conditions, so it seems ok to me. TCXO, OCXO should usually be operated within their operating voltage range. depends on type. usually i would assume 1.8-3.3v, but who knows without datasheet?
You madlad, I don't have much to add but this would be pretty interesting if it worked. Presumably uncooked bone? I also think that using a very thin slice would increase the strength of the electric field, since you want to have a small gap between the plates (field strength is volts per meter). Does the orientation of the bone matter? Could you ask a butcher to cut a slice from a large beef bone?
I tried with cooked bone, that tends to be what I have more of lying around :D
I don't recall the voltage I tried, but it was probably something in the range of 5-9v. I didn't try with a very thin slice, it was a few mm thick. Probably a thinner slice is the thing to try. That's a bit hard with bird bones (hollow), so maybe I'll have to cook something else. I don't have a microtome, so I'll have to cut some thin slices by trial and error.
I would hazard a bet that orientation matters. The studies that measured bone piezoelectricity seemed to suggest some orientations made more sense than others, but I don't recall what exactly. In any case, they had... very different applications in mind.
Mini-PV is the standard (in that DuPont used to make them), but the M20 clones are more common. It was created by Berg, who got bought out by DuPont, who spun those off to FCI and then that went to Amphenol decades ago. Then Harwin made their M20 connectors as a near clone of Mini-PV, but they aren’t a perfect fit with Mini-PV housings (and vice versa). M20 won’t fit in a Mini-PV housing, and Mini-PV will be loose in an M20 housing. Then tons of other manufacturers started cloning M20. Most cheap leads you get will be M20.
I tend to just make my own M20 jumpers since that lets me set the length. Mini-PV is necessary if you want more options for wire gauge or spring tension though.
Looks like you are well on your way for a safe battery. Been playing with these types of cells for years now and I use really thin tinned copper wire to act as a fuse. The real issue you will see if you use “heaters”. These are known cell types typically red Sanyo’s that over time when fully charged start to self discharge which generates heat. Mitigate that issue and they are really stable. I have even direct shorted a 80p pack by accident and all it did was blow the fuses. Anytime you are building this stuff yourself you need to keep an eye on it either with some software that tracks each cell (generally a cell means one parallel set of cells) for voltage and current usage. Also if your bms can record how much any cell balances can show issues before they become a hazard.
My biggest recommendation is to put it outside away from your house. This is the easiest and safest way of protecting your house. Barring the ability to do that a good metal enclosure with exhaust to the outside is a must
The lamp intensity won’t vary in a shunt regulator because the current through the shunt resistor is constant. The current through the zener diode varies to split that current with the load. Otherwise, yes it will work, however you will have fewer choices of resistance and will not be able to make the regulator as efficient.
Any particular shunt resistor that you have in mind? You are correct that the lamp brightness would remain the same whilst in the regulated zone. I was more thinking of operation outside that region - eg in a short condition. Having a lamp as the series resistor would reduce the fault current compared to using a fixed resistor.
Not sure what you you mean by “fewer choices of resistance”. The lamp would be the series resistor - other than that, what resistor did you have in mind?
Standard resistors come in many standard values and many power grades, meaning you can pick a resistor that minimizes source current for your application. Incandescent bulbs come in different rated voltages and powers, but they are far from precise or standard.
Depending on the design, shunt regulators come with short protection for free without relying on a PTC fuse (incandescent bulb or otherwise). You’re absolutely correct that the positive tempco of a bulb will reduce short circuit current, but how by how much and whether it is worth it depends on the application and the properties of the bulb itself.
Another Kicad vote here. Note that even if you don't like it and move away from it eventually, the fact that it's open-source and the file format is documented means you're capable of taking your designs with you.
KiCad. Stay away from closed-source tools. They’ll all try to press out the max amount of money sooner or later. Or get bought and discontinued for eliminating competition.
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