Key Switch - Small

Have you ever wanted to start your widget the same way you start your car? These small switches are the key to making that happen. This simple ON-OFF switch can be used to power up your project with the turn of a key. At only 14.6mm across the top and 23mm long, it won't take up much space in your project enclosure.

While the datasheet does rate these switches for 1A at 125VAC, we recommend using them as input switches or to switch small voltages, such as power to your Arduino. However they can be used to switch small amounts of power.

Key Switch - Small Product Help and Resources

Button and Switch Basics

May 7, 2013

A tutorial on electronics' most overlooked and underappreciated component: the switch! Here we explain the difference between momentary and maintained switches and what all those acronyms (NO, NC, SPDT, SPST, ...) stand for.

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Core Skill: DIY

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Skill Level: Noob - Basic assembly is required. You may need to provide your own basic tools like a screwdriver, hammer or scissors. Power tools or custom parts are not required. Instructions will be included and easy to follow. Sewing may be required, but only with included patterns.
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  • SomeGuy123 / about 11 years ago / 5

    For some reason, the only project idea that comes to mind when thinking of this product is a lockable vacuum cleaner.

  • razor_sparks / about 12 years ago / 4

    Nice! And only a buck! (at the time of this comment)
    Are they keyed the same? They look like they only have 3 pins/waffers...

    • Luc245 / about 12 years ago / 1

      I got 3 all keyed the same so I assume yes.

      • ITHelp / about 11 years ago / 1

        They aren't really keyed at all. Put a key in backwards and twist: It'll move without much resistance at all.

        • I can turn mine with a screw driver. Eh, it's not like I wanted my project actually secure. I just wanted a different way of turning my project on/off than on the rest of my projects.

  • Member #279601 / about 11 years ago / 2

    I installed 6 of these switches in some custom manufacturing tools for my company. One never worked, and I pulled it apart and found that one of the contacts was half missing, as if it had been punched out of the edge of a sheet of metal. Two more have broken during use; both cracked and fell apart at the back, causing the light gray piece (seen in the pictures) to fall out.

    As others have said, these switches are not keyed at all. You could turn them with a small screwdriver, coin, or possibly fingernail (though I haven't tried the last).

    Even the switches that are working feel very cheap, and sometimes have to be turned back and forth a couple times before they make contact.

    I'm a fan of SparkFun, but this particular product is pretty lousy in my experience. I wouldn't recommend buying it.

    • rkvt / about 10 years ago / 4

      You can't expect these to work in commercial settings, they're $.95 parts. These are meant for novelty.

  • roycohen2013 / about 12 years ago / 2

    yea if you look around everyone has sparkfun stuff so its not that hard to find somone else with a sparkfun key lock :D
    and yes im sucking up to sparkfun but it is a good question to ask if they are keyed the same

  • Member #467135 / about 9 years ago / 1

    What do I use to connect to the terminals on the back? Past instances of melting these small types of components make me not want to use solder, and I can't find any crimp-type connectors this small.

  • Reagan / about 9 years ago * / 1

    Wonder if it would be possible to replace the power switch on your computer with this

  • Microman / about 9 years ago / 1

    I own a CDP1802-based microcomputer and this would be the perfect on-off switch, resembling the Altair 8800b's "turnkey" system.

  • Confused, it says AC but they will do DC?

    • MikeGrusin / about 9 years ago / 1

      Yes these will do DC (Direct Current) as well as AC (Alternating Current). For historical reasons switches are usually only given an AC rating. The practical DC rating will be somewhat less than the AC rating, if you don't go above half of the AC rating (500mA in this case) you will be fine.

  • maybe you guys can do a stress test on one of these? say the 1A @ 125VAC you talked about? :)

    • That's a great idea. I will see if I can put something together and test that. I'll update you with my findings as soon as I can.

  • Steven Osborn / about 10 years ago / 1

    I was a bit disappointed in the quality of this item. It's both tiny and flimsy. It's certainly worth a buck, but I'm not sure if it's really useful for any practical application.

  • RedBassett / about 10 years ago * / 1

    These switches are cheap, and good if you want an quick and easy part, however they keys don't fit snugly, are very small (and easy to lose), and I feel like I am going to break the switch with any have use. The housing does not use a ring mounting piece, but rather a pair of depressed tabs on the sides to connect to a faceplate. These tabs slide easily, so the orientation of the switch in regard to the faceplate changes with use. The terminals are extremely small. I haven't soldered these yet, but I imagine it is not easy.

    Even for hobby/novelty use, I would not recommend these switches.

  • This is most definitely going in my "Oh Fudge"!!! along with the missile cover switch, this would be hilarious!!

  • Robo-T0T / about 11 years ago / 1

    My mother had something similar to this installed on the television when i was a kid, apparently i watched too much TV. Although it didn't take me long to figure out how to by-pass it.

  • Microman / about 11 years ago / 1

    Can they be removed while in the on position?

    • ITHelp / about 11 years ago / 1

      Yes. It can even be removed half-way through a turn. (That said, they don't really lock - Anything that goes in the slot will turn the chamber.)

      • Microman / about 11 years ago / 1

        I guess it's more of a rotating power switch then. Perhaps a more accurate name would be useful.

  • Microman / about 11 years ago * / 1

    One could use a relay to lock their computer with this

  • Noobulus / about 11 years ago / 1

    I don't suppose there's a way to use these for DC?

    • SomeGuy123 / about 11 years ago / 1

      It should work with a DC system. Just remember that switching to DC means a slightly lower maximum voltage.

      • Noobulus / about 11 years ago / 1

        I wasn't planning on using them for anything above 9v, so thanks!

  • rileyh / about 11 years ago / 1

    hey i was wondering if this can handle 9v

    • ITHelp / about 11 years ago / 1

      If the datasheet says 1 amp at 120 volts, then yeah: 9 volts shouldn't present any issues, unless you are pushing crazy amps. :-P

      • Member #495246 / about 7 years ago / 1

        Uh that's AC, and the DC rating is going to be way less.

  • esmphoto / about 12 years ago / 1

    just ordered one to throw into a automation/control panel fro the tv studio at my school. looks great, and there are some other cool looking models in the datasheet, especially the on-off-on options, maybe if these do well ya'll could find some more?
    I can find keyswitches at other places for $6-8 but at less than $1 this is a steal.

    • esmphoto / about 12 years ago / 1

      ehhh... just received it an never-mind..
      may be you could grab an on-off-on from another manufacturer...
      the whole assembly feels like in will break before you even push the key in.. doesn't matter which direction the key goes in, there are no pins in the cylinder, its really just a rotary switch with a little slot in front. clearly a novelty.

      • NickVD / about 11 years ago / 1

        My thoughts exactly, I just received mine, and while I am amazed at how small it is, it can be turned by anything that will fit in the slot. It is clearly more for 'security of activation' rather than outright security. In that it will be nearly impossible to accidentally turn the switch, so in that respect it is still useful..
        Just don't be using it to secure a project in any way, as it is NOT A LOCK! :)
        But it's a buck and tiny, I have no issues :)

  • abitkin / about 12 years ago * / 1

    FYI, the switch doesn't hold up to the screwdriver test. If the key escapes you there's that option.
    Oh, I found a 1/2" hole to work the best for this, it fits snugly. That said it will still spin, so hot glue is likely your friend.
    Best look/feel so far for me, 1/2" hole in a 1/4" thick wood panel. I haven't glued it yet, but this feels the most solid.
    Too bad there isn't a nut on the back to hold this in place.

  • JoshFranz / about 12 years ago / 1

    A note on security: I'm not sure how these switches would hold up to a drill, but I would assume it would lose (for $0.95). After that, shorting the leads would give full access to whatever system it "protects."
    Not discouraging it, because I love it, but just don't think you should protect your car, house, or gold with this (alone).

    • Of course. These are $1 switches and are assumed for 'novelty' uses and not meant in any way to secure belongings.
      I think that is assumed seeing as they snap into place and don't have a threaded collar or anything.

      • RobotSpider / about 12 years ago / 1

        I was looking for something like this as a master-arm switch for an air-cannon I built. My only intent is prevent accidental activation. I had given up because it seems like any industrial version of this type of switch runs upwards of $80. This is absolutely perfect.

  • JopieK / about 12 years ago / 1

    So is that just a green and red dot, or are they LED's? I don't think so but want to be sure...

  • Liqdfire / about 12 years ago / 1

    "but they can be used to switch small (^a)mounts of power"

  • Madbodger / about 12 years ago / 1

    It would be extremely cool if the red and green dots lit up, but I certainly don't expect that for less than a buck!

  • Scube / about 12 years ago / 1

    Does the key have to stay in the switch in the on position or can you turn it on and remove the key?

    • Nope, you can remove the key once it's on (or off).

      • chartle / about 11 years ago / 1

        Thats not good for certain applications.

        I have one that I wanted to use for a model rocket launch system. There you shouldn't be able to remove the key in the ON position.

        • Kes / about 11 years ago / 1

          You may want to check your local auto parts store. They usually have replacement ignition switches in the $10-$15 range.

          • chartle / about 11 years ago / 1

            Already have a beefy one that I bought probably 30 years ago that was the right switch. Real key and everything.

            Never got around to building my system. I had all the parts too. :-(

  • Dean_Kreger / about 12 years ago / 1

    Oh man, last summer I went on the hunt for key switches for a project... Only to come up disheartened! So expensive to buy them from DigiKey~, but to be fair, they had some pretty sweet models.
    This would have been perfect though!

  • DigiC / about 12 years ago / 1

    are these switches momentary or toggle?

    • they are toggle.

      • Dirf / about 12 years ago / 1

        That's not the way I start my car =)

        • JoshFranz / about 12 years ago / 1

          Excuse me if I'm being ignorant, but I'm fairly sure you do start your car with a toggle switch... When you turn the key, it stays on until you turn it back. Unless you have a push button start...

          • kbfirebreather / about 12 years ago / 1

            I think he's referring to when cranking the engine to start you rcar. When you turn the key to crank the engine to start, it's a momentary switch, until you release and the key resets back to the position where electronics are enabled. So really he was thinking of a tri-state key lock. off-on-momentary.

            • Dirf / about 12 years ago / 1

              Actually, at least with my vehicles, you can turn the key backward to turn on (some of?) the electronics, forward for on, and then the momentary position for ignition. So I stand by my original statement in saying that this switch, while awesome, does not let me start my widget the same way I start my car.

              • Dirf / about 12 years ago / 3

                But on a more relevant note, I added one of these to my order just because it's $0.95 and pretty awesome, but now that I have it, I've realized it's the perfect for the rail gun I have planned!

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