• RE: 💬 The Harvester: ultimate power supply for the Raybeacon DK

    Here's another one: https://patents.google.com/patent/US20170133938
    He claims the startup power is just 100nW. For contrast, TI says their BQ255xx chip requires 15 uW. i.e. an entire order of magnitude more. Sounds too good to be true, doesn't it? Which leads me to wonder: just how well are patents vetted before they're granted? Might it still be granted even if the author never made a a circuit that performed anywhere near as well as the patent claims? Is anyone even checking?

    By the way, on a different topic, this might interest you: https://www.mouser.com/ProductDetail/426-DFR0579 It's a $12.90, 30mmx30mm, fully assembled breakout for the SPV1050, configured as a boost converter.

    posted in OpenHardware.io
  • RE: 💬 Easy/Newbie PCB for MySensors

    @Mr_sensor said in 💬 Easy/Newbie PCB for MySensors:

    Can I have the pcb in the first shed also working as an extender, so the second pcb will be able to send out topics to the gateway as well? What to add to my code to achieve that?

    you must program it to be a repeater. Of course it will need to have radio on all the time, so it cannot be battery-powered.

    posted in OpenHardware.io
  • RE: Coronavirus (way, way, off topic)

    @tbowmo said in Coronavirus (way, way, off topic):

    I don't know if any of you have seen this before:


    Yes it's famous, I used to watch it daily when there was mainly a big red dot over China, and a few tiny dots elsewhere. Now they had to reduce the size of dots, and it's red everywhere 😞
    I find the table here https://www.worldometers.info/coronavirus/ easier to see the trends, as the main info to know the progress of the epidemic in a place is the number of new cases / total cases and you can see it right away without clicking on each country.

    posted in General Discussion
  • RE: Coronavirus (way, way, off topic)

    Here the federal government has revised upwards its projections regarding # of infections, # of deaths, and the date of the "peak". They didn't have much choice, given that their prior projections would have soon been invalidated after-the-fact. Their new projections, especially regarding the "peak" date still seems far too conservative. I can only assume they are simply trying to avoid mass panic. Locally the governor has ordered that everyone not involved in giving or receiving essential services stay at home. Finally!

    At least so far no one has talked about whether the food delivery infrastructure will be critically damaged. Because it is a high priority, though, I presume that to one degree or another it will continue to function. Some food items are being rationed, and a few categories, like dried beans, have been wiped out, but overall getting enough food to survive doesn't appear to be a problem if you have the money to pay for it. However, with large segments of the economy effectively "turned off," it seems likely that large numbers of people will be running out of money soon, and with the government here being slow to react...

    Anyone have an updates for their country? I'm interested to hear more about Viet Nam, since it sounded as though it was doing well and there's so little coverage in the press here about it. Unfortunately, the case of China, there's a lot of suspicion that China under-reported how badly they were affected, which would surely have contributed to the under-reaction in the West. The data from Italy seems solid though. It it weren't for the Italians generously sharing their experience, I'm sure things would be even worse throughout the world.

    I'm not sure how much the hospitals can actually do that makes a difference. I had previously read a WHO article that had said that oxygen, which is the first line treatment, didn't actually appear to change the outcomes, though it can keep you alive a bit longer than without it. I'm hearing that 70-80% of those who do advance to ventilation and intubation end up dying even with the added support. I mean, I'm not saying we shouldn't try to do all that we can, just that even our best efforts may only occasionally help--which is suprising. I had thought modern medicine, when properly administered, would make more of a difference.


    posted in General Discussion
  • RE: Coronavirus (way, way, off topic)

    If you have a weak temperament or are easily upset, you may want to stop reading now.....

    OK, then, for those who are still reading... I think we all have a shared interest in vetting out what is real vs propaganda. Therefore, how is it that as of this morning the news media is projecting "only" 20,000 dead in the UK and maybe "only" 200,000 dead in the US? Those sound like linear extrapolations to me, not exponential ones. If instead covid-19 really is doubling every 3.5 days, as I've heard from MD's, then in 5 weeks time it's going to be 2^10, i.e. 1000x, worse. Right? So, by that rekoning, in the UK it's going to be a million dead or dying and in the US about 2.5 million. In just 5 weeks from now. Even if social distancing has slowed the rate, the media numbers for the total cost (not just 5 weeks from now) sound way, way off. Or am I missing something? Even if we manage to "flatten the curve," then short of a miracle, that only means it will take longer for the 1000x damage to occur, not that it's going to be avoided. Right? Meanwhile, due to shortages that haven't yet occurred and so aren't yet reflected in the early numbers, I'd wager the outcomes will be even worse than 1000x worse. Does anyone here have a different viewpoint? It seems to me that the official projections are incredibly low-balled, and so they are actually contributing to the problem! The best way to flatten the curve would be for people to have accurate projections, because then they'd be shocked out of their complacency and not be taking unwise risks.

    If you can possibly stay at home and not go out at all for anything for the next two months, I think you'd be wise to do that. Why? Because within that timeframe the actual trendlines should become a lot more apparent to everyone, and so by then people will have dialed in more closely to whatever the actual risks are and adjusted their behavior accordingly. To draw an anology, right now it's like Chernobyl just happened, and yet people are still attending parades outdoors the following day (which is what actually happened) because they were not made aware of the true risks.

    posted in General Discussion
  • RE: Anyone tried the stc15l204? It appears to be an inexpensive integrated mcu + NRF24L01+

    @alowhum Yes, you'r right. Based on this review (https://www.embedded-computing.com/guest-blogs/for-the-professional-maker-getting-started-with-the-rf-nano-arduino-nrf24l01-combo), it has exactly the same pinout as a regular nano, and so it sounds like the RF-Nano is very much the kind of simple, affordable, standardized, fully integrated, wireless Arduino that Arduino should have released 6 or more years ago as an "official Arduino," but just never did. Of course there are more powerful alternatives available now, but I bet it could it still be exactly the sort of thing that a true beginner who had only just learned a little about the Arduino Uno might want as his/her first step into wireless.

    posted in Hardware
  • RE: Anyone cleaning the flux off using an ultrasonic cleaner?

    @bjacobse Excellent! You're the first and only person I've ever met who knows anything about this very important topic.

    By "hydrofob", I assume you mean hydrophobic coating? If so, just how effective are they at preventing moisture intrusion, and which type or brand of hydrophobic coating is the best?

    posted in General Discussion
  • RE: wristwatches that invite development

    Quite a large number of inexpensive nRF51/nRF52832 watches which appear to have already been hacked, documented, and made available for others to now hack too: https://github.com/curtpw/nRF5x-device-reverse-engineering

    posted in General Discussion
  • RE: 💬 The Harvester: ultimate power supply for the Raybeacon DK

    Here's a courtesy heads-up.

    I just now stumbled across a circuit:
    alt text
    published here:
    that allegedly can operate on as little as 10na while collecting energy, which it then uses to power a small pager motor once a threshold voltage is reached.

    It also has the virtue of utilizing inexpensive jelly bean parts and not relying on gigaohm resistors, which in the Dave Johnson circuit turned out to be so large that I lack the means to verify their specs through measurement after they are delivered.

    This other guy instantiated the circuit as a PCB, and he made the gerber for it available as a free download: https://hackaday.io/project/159691-electron-bucket-extreme-power-management-module

    If it turns out to be true that the circuit can both collect the current and trigger at a threshhold voltage all with just 10na of overhead, then on its face it sounds better than the David Johnson circuit turned out to be and possibly also better than many/most/(all?) of the commercial chips that we've reviewed on this thread if paired with an appropriate amorphous solar panel.

    But wait! There's more. There appears to exist an equivalent single chip voltage detector that also consumes a mere 10na of current: https://www.akm.com/content/dam/documents/products/power-management/power-ic-for-energy-harvesting/ap4405aen/ap4405aen-en-datasheet.pdf
    It's itty bitty, so it's probably a great fit for your uber-compact design.

    "But I want more!" I can hear you say. "I want a total step-up solution! And I want one that doesn't use a transformer!" Well, of course you do. Who wouldn't? Apparently, a 0.2v transformerless step-up solution does exist as well. I'm just not sure where. They developed it for a customer who wanted to harvest energy from... bacteria. Actually, the official term is "microbial fuel cell." The chip is the AP4470, and thankfully it can also be powered by solar, without bacteria.
    But can we buy it? Or is it just another inaccessible research project? I don't yet know. Can you read Japanese? The trail of bread crumbs written in English seems to run cold after the above link, but there's more about it that's written in Japanese. Argh.

    posted in OpenHardware.io
  • RE: Next generation dust sensor for MySensors

    @Sebex said in Next generation dust sensor for MySensors:

    @NeverDie could you share your Honeywell code, I have trouble getting it to work. An example will help me a lot t learn from!

    I made a library for that, I'm updating it to autodetect some various PM, CO2, Formaldehyde UART sensors but I'll find the old version for Honeywell only tomorrow if you want. If I forget, harass me by MP 😄

    posted in General Discussion