Minimalistic Doorbell Doesn’t Need An Internet Connection – Or Even A Power Supply

A doorblell made from a stepper motor and a hard drive

Doorbells are among those everyday objects that started out simple but picked up an immense amount of complexity over the years. What began as a mechanism to bang two pieces of metal together evolved into all kinds of wired and wireless electric bells, finally culminating in today’s smart doorbells that beam a live video feed to their owners even if they’re half a world away.

But sometimes, less is more. [Low tech obsession] built a doorbell out of spare components that doesn’t require Internet connectivity or even a power supply. But it’s not a purely mechanical device either: the visitor turns a knob mounted on a stepper motor, generating pulses of alternating current. These pulses are then fed into the voice coil of an old hard drive, causing its arm to vibrate and strike a bell, mounted where the platters used to be.

Besides being a great piece of minimalistic design, the doorbell is also a neat demonstration of Faraday’s law of induction. The stepper motor is apparently robust enough to withstand vandalism, although we can imagine that the doorbell’s odd shape might confuse some well-meaning visitors too. If you’re into unusual doorbells, you might want to check out this one made from an old wall phone, as well as this electromechanical contraption.

57 thoughts on “Minimalistic Doorbell Doesn’t Need An Internet Connection – Or Even A Power Supply

  1. My door has a knocker. No power needed, no wires either.
    However, UPS refuses to train their drivers how to operate a knocker, so they don’t use it. Instead they fill out a little card as their excuse to not knock, which actually has a box to check saying “knocker”.
    It’s curious they know how to write with a pen, but are unable to figure out how to operate a knocker.
    I might have to install a pushbutton doorbell just for them.

      1. Oooh, permanent magnet on the aluminum knocker then an electromagnet on the door that, when activated pushes the magnet away (EMP). Simple and doesn’t require motors, microcontrollers, or RPIs

      2. Mount the knocker assembly on inside of door, and have a spring holding the swinging hammer part , up about a half inch.
        Drill a tiny hole into the door right under where the knocker hammer is .thread a wire or strong string through the door.
        One the end inside , tie it to the hammer .
        Tie the other end to a ring.
        When you pull the ring/wire it will force the hammer to hit. Releasing it, the hammer lifts again

        Mount a little sign UNDER THE RING,
        “PULL TO KNOCKb

    1. That would be pointless, I have both a knocker and a pushbutton doorbell, and some of them can’t be bothered to use either.

      The worst culprits leave the parcel by the front door (on a busy road/pavement) and run away.

      Luckily most of my little grey chinese parcels get posted through the letterbox anyway.

      But I like the idea (below) of magically operating the knocker with the pushbutton, I shall look into it!

      1. “The worst culprits leave the parcel by the front door (on a busy road/pavement) and run away.”

        They’re scared of you. :-D

        One could have a “pull level” connected by bicycle cable to a bell mechanism inside the house.

    2. Some Victorian homes have a knob that you twist that rings a bell. It’s easier to hear than a knocker. Of course it costs more and it’s more effort to install.
      I always wanted a pinball plunger that you pull back and release to hit a ball into a metal bucket, or strike a china cymbal, or something. I find pinball machines to have a very satisfying feel to them.

      1. that was the standard doorbell here in the Netherlands in the early 1900’s. a plunger with a lever on the inside connected to a bell on a spring with a piece of wire.
        but of course a plunger connected to a gear rack and pinion for the stepper and a spring to return it to the neutral position would also be great

    3. I can clearly see a wire coming out from the other side of the wall from the switch. It comes out, hangs down and comes back up the to bell. But you have it sitting on a white bed sheet or something which is weird to kinda hide the wire going to it. So making it seem like it runs on electro magnetism through the air or something is a lie. Mechanical… Probably. But then again, being mechanical would be enough of an achievement. You wouldn’t try to hide wires bc that would be part of the mechanics. Web of lies! Sorry!

      1. I think you may have got the wrong end of the stick here, they’re not trying to hide the wire. It doesn’t run on electro magnetism through the air… it runs through the wire.

    4. Your UPS guy will actually get out of the vehicle and walk to the door? That is great! Mine insists on dropping things out the door at the end of the driveway,, well, used to do that when I was still using UPS.

      1. That ain’t nothing.
        From my kitchen I heard the UPS truck . I leaned down looked out the front window across my parlor, through the den, and kitchen I watched the UPS guy never lifting his butt. The guy lean to his left, picked up a package, did his electronic scan thing, then leaned over to his right and tossed it NEXT TO my mailbox.
        My mailbox even has a separate large package area under the mail box bottom
        He drives away, and ALEXA confirms the delivery .
        I go outside, go to pick it up, and I’m in AW.
        it’s in a pile of dog crap.
        No doubt, either GOD or Satan himself must’ve been looking out for that guy.
        Because my wife had taken the car 10 minutes earlier.

    5. Paul, youre a clown. You really have nothing better to do than complain about hard working UPS drivers? I guess getting you package wasn’t good enough you have to be overly controlling… do you even know how hard they work? 6 days a week. 9-8pm. With hundreds of stops a day in and out of the truck. They have one of the highest repetitive injuries. I hate people like you

    6. I guess this brilliant liberal isnt smart enough to sign up for ups alerts when packages are delivered. Probably still has flip phone. Who uses door knockers when you’re immediately notified of drops.

    7. This same problem has bedeviled me for years, Pardon me – I meant to say: YEARS!!! This failure to train drivers to perform a simple biomechanical procedure has given rise to a new, and previously unknown industry! “Following UPS and AMAZON and FEDEX trucks around all day and stealing their deliveries from the front steps of poor slobs who are home, but cannot hear the footsteps of the delivery drivers”!!

  2. An interesting thing to note about using steer motors as generators, they can generate in excess of 45V even at fairly low speeds, compared to say, a brushed motor. They can also offer enough current to be felt as a shock on your fingers, let alone your tongue.

    1. Are you from Russia? “In Russia, current tests you!”

      I use a multimeter rather than random body parts :)

      Though, it might be entertaining if I used other peoples body parts!

      Maybe and old Mega (that generates about 600 Volts when you turn the handle / crank) and wire the output to the handle.

      “Can you see who’s screaming at the door please”

  3. Should mount a crank on the stepper motor’s gear.

    Or maybe turn the stepper 90 degrees, then set up a button, attached to a sector gear that meshes with the stepper gear, so that you can push a button to turn the stepper.

    1. I think the house across the street in the sixties had one of those. I’d forgotten, but your comment reminds me of twisting to ring the bell.

      But I also remember a broken doorbell button, touch the wires together to ring the bell.

  4. Look at any old movie (or a wall-mount phone old enough to be in one) and you’ll find the hand-cranked generator that did exactly this, creating a jangle on both ends of the connection.

    1. A jangle at the operator only, then she connected you to the other party whose bell the operator rang. Voice assistant all the way back then. The first party could have been doing the cranking but only after being connected.

      Take the magneto from the phone and connect to two rods driven in to soil and crank up some worms to go fishing! Roughly 90volts at 20cycles.

      1. I was helping the IT people at work last week trouble shoot some phone issues and one of them was pointing out the circuit by touching the punch panel, I winced as that damn 90v 20hz is burned into my brain after working telcom / network for almost 2 decades

  5. For a more “doorbell” feel, and easier for the general public – i.e. the uninitiated – to use, you could connect the stepper gear to a lever. Push the lever and it turns the gear. Release it and a spring returns the lever. Same action as a doorbell button but with the same technology.

  6. I’m still looking for an openwrt for doorbells, and a doorbell that can run it. So far, nothing.

    I fear that even these doorbells do “secure boot” and have locked bootloaders, because “security”.

    Of course these devices are rarely secure, or rather secure for the user (spying etc). When we all knowbits just a form of DRM. Software can be repaired too.

    I hope right to repair fixes this at some point to. My device my software.

    1. I have an Orion video doorbell which is performing poorly and getting dangerously close to a tear-down and good probing. I’m expecting a embedded Linux distro so I’ll start with a bit of port probing.

  7. This is reminiscent of early phones that had the crank on them.
    They would generate a high voltage (I think AC though not positive) that would cause a bell at an exchange to ring.

    I think anyway. I’m not that informed how they work. I just saw a couple and thought they were interesting curios and didn’t do any extra research

    1. The cranked generator would send 60 to 90 VAC down the line and at the manual exchange an capacitor coupled electro magnet (like a solenoid) would release a hinged flag that would then expose the 2 to 3 digit phone number on the operators switchboard.

      The operator would then flick a switch to use a set of patch cords to talk over and plug one end into the socket below the exposed number and asked the person what number they wanted. The operator would then plug the second lead of the patch cord into the destination number and crank another ringer or simply press a button to ring the second phone, when they answer the operator announces the calling number and asks if they accept the call, and if they accept the operator flicks a switch that disconnects her headset from the conversation and illuminates a light to say the circuit is active. She then fills out a log book about the call for charging. When the second phone hangs up the light goes out and she pulls out the plugs from the patch lead, manually flicks the hinged flag with a finger and completes the call time in the log book.

      On longer distances to the customer phones they had two DC batteries with the phone to boost the signal (for speech) due to the attenuation of the long line.

      1. I always wondered how those switchboards (and the name thereof) operated, and how the calls were charged, when I watch old film noir… Many thanks for that!!

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