The best advice I’ve seen online (ok, it was ChatGPT) is that it’s just not worth it to work with such small amounts of electricity, because the equipment required is too expensive and sophisticated (e.g, devices to read the charge of a capacitor without discharging it) to make anything that’s efficient enough to be worthwhile.
I guess ChatGPT has never heard of passive RFID tags? LLMs have some good uses, but they’re not great at a lot of things. You can’t really advance science and engineering by strictly regurgitating scraped text.
There are reasons to grab small amount of electricity from the environment. Why have a battery in a pacemaker if you can generate power via mechanical forces? It really just depends on the use case on how practical and feasible it is.
Oh yeah, I hear you on LLMs. Technically, ChatGPT has not “heard” of anything. It’s generally something I use as a jumping-off point when I’m desperate and don’t know what search query to use.
Does passive RFID harvest its power? I don’t know much about RFID (I’ll probably head over to wikipedia after this comment) but I figured that it was a circuit that, when given a bit of energy from a reader, sends back an RF signal with an encoded ID and that in the absence of that powered reader, the RFID device wouldn’t be transmitting anything.
Yes, the circuit in an rfid device gets its power by harvesting energy from the RF source it’s being illuminated with. A smaller version of wireless power transmission first invented by Tesla (the person, not the car company). Similar principles were used in the Cold War for surreptitious listening devices. Neat tech.
The most basic RFID tags will just send back an ID. The complexity can shoot way up and have all sorts of integrated circuits, mostly around encryption.
I guess it’s more of a semantic argument at this point, but would you not consider a tiny computer (RFID tag) that powers itself solely off of radio waves not a form of energy harvesting?
I guess the difference for me would be how long it stores that energy for, but the difference is probably semantic and easily changed with a few capacitors.
I would say “energy harvesting” is when the receiver and transmitter are not designed to be used together and they are not physically close together. Otherwise your electric toothbrush and Qi charger might count.
That’s a good point. What about long range RFID skimmers? You could argue the tag wasn’t designed to work with a skimmer. I guess that’s more like energy injecting?
No, moving a ferrite core through a coil won’t generate a voltage. You would need to move a magnet to generate a voltage.
Look for a vibration switch like one of these. If you want more control, you could use an accelerometer and a microcontroller to trigger it from a specific amount of movement.
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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.
Kester 63/37 no-clean 22AWG for leaded work, SN100C no-clean for RoHS. Mg chemicals and chip quik are good alternatives, Kester can be expensive to justify for home use.
There is an answer but you’ll probably only manage to get it by going through semiconductor devices history and determining the hardware required at each improvement step, and the cost and acquirability of that hardware. This would take hours - potentially days - of research.
A quick search yielded this blog post though of someone attempting - and managing - production of a basic 1200-transistors semiconductor device in their garage, which I found rather neat. That’s with no cleanroom, and with chemicals the purity of which are far removed from the ones the industry uses.
We’ve had open-source chip design software since the 1980s. Magic VLSI, for example. There are quite a few OSS tools for various parts of the chip design process.
I dont think the resistors are faulty but the design. Resistors (especially low-ish value 22Ohm ones) are meant to dissipate energy as heat. Putting them in a cramped housing made of plastic, then using them to dissipate high power is going to build up heat in there. There could also be another component faulty that puts too much current into the resistors. They are probably part of the balancing circuit.
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?
Unless you've managed to get a switch made out of superconducting material and you're working inside a liquid helium bath, everything has resistance :)
You'll have a bad time trying to measure such low resistances, so usually you can look at the datasheet for the switch you're using or for a similar switch if you need a ballpark number. You'll see an on-resistance, and a max current (since there will be arcing when you open the switch).
If you do want to measure the low resistance, you'll need dedicated meter with a kelvin connection.
Thanks for the feedback and info, I'll know what to look for next time. Unfortunately, I purchased a tattoo pedal as the momentary switch, thinking it would be easier to operate. link Btw. thanks for clarifying everything has resistance, that concept confused me more than I thought it would.
Only having one ADC can be an issue when you need readings to be in phase, but for reading any sort of human interface device it doesn’t matter at all. Just cycle through your inputs one at a time. Some microcontrollers even have hardware to scan through multiple inputs automatically. You can use DMA to read the ADC and send data out over whatever communication peripherals your microcontroller has without using much CPU time.
If you are using USB HID, you are limited to a 1000 Hz update rate and that’s really overkill already. You can have up to 8 analog axis in a USB HID game controller plus lots of buttons.
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