NewbiePCB sensors dying of old age



  • Been a while lol Im still here though, running sundbergs PCBs around the house.
    Seems the battery powered ones are dying. I used cheap chinese clones for everything. Interestingly, the ones I have running off wall sockets or USB power just keep going and going, no probs at all.
    One wont get ACK or reach the controller. One I cant even talk to through the Ardunio IDE, another two wont accept uploads of new code, just sits there 'uploading' forever. another one is just dead dead, I got 3V from new batteries but nothing, nada, zip. Even my two nano's that were just sitting in a drawer for years seem to have expired. If I had a reflow oven I might give that a go as nothing to lose. I wonder if its a lead free solder thing. I have tried redoing the joints on a couple with a new tip on my hakko but made no difference. I cant really pull off/replace the NRF or pro mini as it will bugger the traces.
    <shrug> lol just looked back in my emails and I ordered sundbergs PCBs in 2016 so seven years, cant expect miracles eh.
    What Im gonna do now is m26872's slim nodes. I have the 328Ps and heaps of NRFs just waiting on the PCBs. As you get 10 that will mean 30(!) boards. I only ned around six but great to have spares. Programming bootloaders will be a new experience, now that my nanos have died I have also ordered an UNO to use as ISP. I think Ill just go for an 8Mhz bootloader as Im worried about issues with timing over onewire, I will be using mostly DS18B20s. Its cool that these chips have internal oscillators as well as vref so minimal components.
    Sort of excited again, MySensors remains a hugely valuable app for me, thankyou Hek et al.


  • Hardware Contributor

    Hi @Matt - yea, i experience the same, my nodes with the Chinese voltage boosters/converters seems to be dying and my guess has been noice from those components. Im converting more and more over to 5v power from wallsockets and stuff and I also found the 433mhz radios more reliable than the NRF radios still... but I'm really happy, I still have some nodes up that is probably around 10 years now - way longer than I expected 🙂 I mean, that's sometimes better than bought nodes 😉

    Agree with you that learning new stuff is the best with this kind of projects - I have also used the smaller slim nodes and they have some applications. But Im actually moving the other way, to bigger nodes - with modular components. I have to resolder and program everything again so if possible when a node fails I can easily change the component. For example, my gateways now uses "shields" that I can just plug and play on a Uno with easy changeable radio.



  • Hi sundberg84.
    Yeah you're probably right it's something to do with the boost converter eh. I'm still dead keen on battery power hence the slimnodes. Although I'll be putting 8 and 28 pun ic sockets on the pcb so I can swap out either the 328p or nrf if needed. Haven't gone down the rfm route.
    I do have a single 833mhz transmitter to talk to my wall sockets has run continuously for 7 years off USB.



  • I had something similar with one of my homebrew barebone sensors: It ran for two years on one pair of AA batteries then I replaced the batteries and it lasted only 2 months. So changed again the batteries and it ran only 2 weeks.
    I measured the current and it turned out it was drawing a few mA instead of uA while it was sleeping.
    Turned out that one capacitor was leaking. Replaced it and now it has normal sleep current.


  • Hero Member

    Some humidity sensors are known to lose accuracy with age. For instance, the Si7021 is known to have this problem. If that matters to you, then the best choice is to pick sensors that have datasheets and which have specs as to their expected longevity or accuracy over time. Then buy from mouser/digikey to be certain you're getting the real thing rather than factory rejects or counterfeits.

    For extra insurance, I avoid electrolytic capacitors entirely whenever possible. I buy only 7XR rated ceramic capacitors that are overspec'd. The difference in price is small compared to a failure down the road.


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