Old Phone, New Remote Switch

With mobile phones now ubiquitous for the masses in much of the world for over two decades, something a lot of readers will be familiar with is a drawer full of their past devices. Alongside the older smartphone you’ll have a couple of feature phones, and probably at the bottom a Nokia candybar or a Motorola flip phone. There have been various attempts over the years to make use of the computing power the more recent ones contain through using their smartphone operating systems, but the older devices remain relatively useless.

[Vishwasnavada] has a neat plan though, using an ancient phone as a remote trigger device, by interfacing it with an Arduino. There are many ways this could be achieved depending on the model of the phone in question, but one thing common to nearly all devices is a vibration motor. Removing the motor and taking its power line to a GPIO allows the Arduino to sense when the phone is ringing. The idea then is that a call can be placed to the phone which is not picked up, but because it triggers the vibration motor it can be used to make the microcontroller do something remotely. A hack with limited capabilities then, but one that is cheap and simple, uses a recycled device, and should work almost anywhere populated on the planet given the global reach of 2G networks.

This isn’t the first respin of a classic Nokia we’ve brought you, they will also talk data.

38 thoughts on “Old Phone, New Remote Switch

  1. > and should work almost anywhere populated on the planet given the global reach of 2G networks.

    You mean the one that’s been decommissioned in lots of places already and is on the way out in others?

    1. Yep! I was going to comment.. I’ve had projects like that stop working on me now as the GSM networks are all shut down in most(all?) of Australia.
      Now we are working to re-use the cases of these classic devices for other projects.

    2. 2G networks will survive 3G. in many eu countries operators have a lot better coverage with 2G than 3G. and when it comes down to voice calls, it all the same crap. usually regulators limited the freq spectrum for 3g to higher frequency. – that trsnslates to shorter range/more LOS dependdnt, so in general almost everywhere you have better coverage with 2G. in eu regulators pushing lte deployment to lower frequencies, and operators are more interested in having good lte coverage than 3g. if you make a voice call in rural area, the chances you fall back to 2G instead of 3G are a lot higher. tbh volte is just an overly complicated reiteration of the classic mobile voice, snd int many cases you’ll end up on cell switched voice snyway, and there’s no mechanism available to rlevate your call back to volte again. but anyway, who needs voice calls nowadays…

      1. LTE has wider coverage than 2G because it’s being pushed to lower frequencies to increase cell size. Old UHF channel space is starting to get used for mobile operations.

        1. it wasn’t about LTE. it was about 3G.
          but say LTE coverage will be better soon – i agree on that. but LTE (luckily) doesn’t have no native voice solution, unless you consider VoLTE as one right now. but even if we say, VoLTE is the way to go (it is at least more efficient on bandwidth compared to its predecessors), the amount of VoLTE capable terminals is a minority compared to the rest. so people as they make a voice call, fall back to 3G or 2G.
          and the point of the article was to set off something “good” with just an SMS or phonecall, wherever you are.
          there are a lot more convenient ways to do this with LTE: like Cat-M1 – but the stuff is not there yet.

          1. otoh you can get those phones with battery everywhere for a couple of bucks, if you want to be looked at as a wannabe bomber. or you can get sim800l modules on ebay/aliexpress for next to nothing (~US$4 or so), which are quite a lot maker friendlier than any old phone – but you have to roll your own power management there.

  2. Quote: The idea then is that a call can be placed to the phone which is not picked up, but because it triggers the vibration motor it can be used to make the microcontroller do something remotely. A hack with limited capabilities then, but one that is cheap and simple, uses a recycled device, and should work almost anywhere populated on the planet given the global reach of 2G networks.

    Cheap and simple? You’ve got to be paying the bill on that cell phone account each month.

    That aside, given the billions of cell phones that’ll be made in the next few years, perhaps there should be a requirement that they have a post-cellular mode that’s still useful—maybe as an alarm clock or a camera for children. Give it a few more years of life. It might even be turned into a short-ranged two-way radio, with some button as push-to-talk.

    I did that with my iPhone 3gs. I left it charging with the screen on and ran a weather app. Presto, I had a continuously visible weather report on my desk—that is until the battery swelled up and died. My iPhone 5 is headed for a similar fate.

        1. Heat is a big factor as well, as was commonly experienced in the days of Perk mining. One hack was to remove the battery and replace it with a power supply. For massive Perk mines, one common solution was an ATX PSU with a diode per phone to drop the voltage, also yielding a source of 12V to run cooling fans.

        2. No it freaking is not the failure mode of lithium batteries. The failure mode is migration of the ions resulting in gradual loss of capacity and a graceful retirement, bulging battery packs is what happens when you let shills for certain electronics companies tell you what is what.
          If you overheat lithium ion electrolyte it breaks down into hydrogen but it doesn’t do that with normal charging cycles (0.5 of capacity per hour) only when you cram the pack in a bunch of white plastic next to a processor with well below the bare minimum of ventilation.
          Let me be ABSOLUTELY CLEAR at no point is a bulging battery pack
          1 normal in proper usage
          2 safe in any way
          3 acceptable for a properly engineered device much less a UL certified one

    1. > Cheap and simple? You’ve got to be paying the bill on that cell phone account each month.

      You do realize there are parts of the world where you can easily get prepaid cards valid for 12 months since last top up worth a couple of dollars? Or a contract with no monthly fee, just whatever you spend on calls and texts? Or an secondary SIM card for your existing contract that shares the same pool of “free” minutes? Just sayin’.

    1. It’s pretty common knowledge that this *exact* type of hack has been used to detonate countless IEDs. Whoever posted this must have known that it would be pointed out in the comment section

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