Make Your Own Reed Switches

[Lucid Science] shows us how to make some simple reed switches. Reed switches are simple components that detect a magnetic field and can close or open a circuit once detected. While not really a thing of beauty, these DIY reed switches should help you out if you just can’t wait to order some or you fancied trying your hands at making some components from scratch.

Reed switches normally come in very small form factors so if you need something small then this may not be for you however the video does show you on a macro scale the fundamental workings of a reed switch. To make your own reed switch you need only a few parts: some copper, enamelled wire and magnets. They really are simple devices however sometimes it’s easy to overlook how simple some things are when they are so small that you can’t really see how they work.

Making your own components from scratch is probably the best way to understand the inner workings of said component. In the past we have seen some pretty awesome self built components from these beautiful DIY Nixie tubes to even making your own LEDs

19 thoughts on “Make Your Own Reed Switches

  1. Aren’t window switches for alarm systems reed switches? I would think so, but I’ve not looked. I was thinking that the plastic is there to make more mountable switch, and inside would be a small reed switch. And I figured those indow älarm switches would be readily available.

    That’s not to say that there’s no value in doing ths.


    1. Yes older ones at least.
      The magnet is mounted in the moving part (door/ window pane) while the Reed switch is in the non-interference frame.

      It’s likely that modern units are hall effect.
      It’s quite easy to fool a simple reed switch from outside to break in.
      Hall effect switches at least have capacity for the Alarm to detect CHANGES in field, not simply presence or absence.

      1. Likely that they are still on-off only not measuring tampering, unless government level. It also takes more wires. Funny that they incorporate hall sensors into smart meters, after they said magnets wouldn’t affect electric meters.

        1. Why would it take more wires? Just place a small microcontroller inside the switch and let it do the work of determining when the magnetic field has changed enough to indicate an event. Coming out of the switch you would then have the same two wires that work on any old security system manufactured in the last several decades.

      2. I think it is not so easy to fool them. They need a field gradient (N-S) in their longitudinal direction to be closed. When you expose them to just one pole of the magnet from the side, you even open them. Now try, through a thick window frame, without knowing the exact position or the direction of the field that closes them, to keep them closed by a strong magnet from the outside. As the contact is closed at the beginning you have no real indication when you try to manipulate it – except when the alarm suddenly goes off, because you accidentally opened the contact with your magnet.

    1. Over the years Hackaday presents articles on how people have built their own mechanical/electrical components. Not simply because someone made it but also because it helps illustrate the inner workings of pieces that people normally take for granted because they’re purchased pre-made and tested. The experience level of the readers here greatly varies and so these articles are good to have. To your comment of “LifeHackaDay”; I do believe the idea behind a “life hack” is to make doing specific day to day tasks easier, or to streamline one’s life. Being that it is far easier/convenient for the majority of the readership to purchase the part, I’d have to say this fails as a life hack.

    2. I’m with Nicholas. There’s no way this is a lifehack. It’s an instructional piece about a common electronic component. There was some real info in the video, even if you already know how a reed switch works. None of that is helpful in the “save money on dishwashing detergent” sort of “life hack” way.

      Your comments have become slightly negative, entirely insubstantial, and basically a waste of space lately. Please consider improving their quality, or just refrain from posting them.

  2. Now I imagine a simple circuit with a normally closed reed switch driven by a electromagnet. The reed switch in series with the electromagnet offcourse…. sort of useless device. I expect it will be oscillating.

  3. I could be wrong, but I thought the contacts in a reed switch were ferrous rather than magnetic. If you’re going to explain the fundamentals of how something works, at least make sure you know how it works.

    1. You are right. I did not read about a magnet in the article, although the picture looked like a magnet. I did not bother to watch a video at the moment, so I did not even notice this mistake in this experiment.
      Another fundamental quality of a real reed switch is that the contacts are sealed under inert gas. So this crude experiment of a magnetically actuated contact has not very much in common with a real reed switch. :-(

  4. With a reed switch you have two ferromagnetic reeds that become temporarily magnetized and are attracted to each other, making contact. Reed switches have no actual magnets in them. Seems the editors should try doing research before letting things through with misleading topics?

  5. Looking through the original patent of a “reed switch” had you sold this when it was still in effect I think you would have some lawyers chasing you. The glass tube with inert gas is only to stop corrosion. So I am going to stick with the title and call this a reed switch albeit a very crude one.

  6. Came up with something even better! Magneto resistive.
    Its possible to make your own variant by taking a very thin piece of Bismuth and forming a thin wire with it.
    Mechanical or electrochemical etching will work, as will low temp soldering a piece at both ends.
    The thinner you can make it the better.
    In fact there are easily made alloys that are far superior though even more complicated to connect.
    I found that the alloy used in washing machine and motor brushes will work and is called “Carbon solder”.

    For certain subsets where you want a linear sensor its ideal!

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