Do math to turn off your alarm clock

[nickjohnson] sent in what might just be the most incredibly evil alarm clock ever. It’s a fairly simple pic project with a PIC, LCD and input buttons. When the alarm goes off, you have to solve math problems before it will shut off. If you answer correctly, you make it stop. In my case, I’d probably add a mute button that can be held down while you do the math. Source, schematics and pcb layout are provided.


  1. dioxide says:

    Sweet. I might do one…

    I’d make that mute button timed, so that you have to solve it within 10 seconds or so and if you don’t, it un-mutes permanently (or gives you a second chance and then un-mutes permanently)

  2. andrew says:

    hahaha now that’s clever!

  3. dioxide says:

    Another idea I have is to make it binary, for the true geek/l33t h4xx0r, it would be a combination of binary display and lcd, so that you have to make the indicated operation with the binary numbers and get it right or suffer the consequences

  4. scooter says:

    Most of the time, I wake up in such a sleepy haze, that I think the mysterious sliding switch on my alarm clock actually has to be reprogrammed to shut it off. I guess that’s how I justify to myself that I sleep through it all the time and let it buzz for ages.

    I love the idea of this clock, but my wife would either shoot me or the clock… Since I sleep between her and the clock, my odds aren’t good.

  5. Sean says:

    I used to accomplish the same thing by putting my alarm clock across the room, but this is way cooler! Maybe I should make one that forces me to do floating point. If I can do that in my sleep, I arguably no longer need to be awake.

  6. Zencyde says:

    I will definitely agree that this idea is pretty genius. : ) I know that I’ve gotten to the point where I can disable alarm clocks just as easily as I can hit the snooze button; but, I’m in too much of a daze to realize that hitting the off button causes me to fall asleep. Great ability to analyze… huge lack of forethought. XD Forcing me to do math? I’ll be sure to be awake after that…

  7. ben airy says:

    You don’t want to do binary arithmetic. At least I don’t. It’s way too easy, but for most of us mortals, other mathematical operations in binary are not quite second nature.

    Converting a decimal number into binary seems to be an easy compromise. Easy to implement, just have a pair of seven segment displays and a row of momentary switches with corresponding LED’s. The SSD’s display a number, and when you switch on the correct LED’s, the alarm stops. You could add a pressure switch that you have to hold (to keep you from dozing off) that mutes it.

    I could do this whole thing with a decimal counter and some basic logic. No PIC needed. I consider that a perk.

  8. PKM says:

    I’m with ben airy/dioxide, the mute button would have to be recessed into the side of the clock to stop you resting something on it. for me though, nothing beats the s.a.d. light on a timeswitch (80 watt daylight spectrum fluorescent light that kicks out about as much light as an open window). light > sound for making you actually wakeful rather than just not asleep.

    still, I love the idea- it’s like a little tiny bit of dr whatshisname’s brain training in the morning, and that’s probably a good thing.

  9. Taehl says:

    I remember this one site (the link is new dead, sadly) which sold an alarmclock somewhat like this. Instead of making you do math, it launched a little spinning helicopter thing, and wouldn’t turn off the alarm until you got out of bed, found the thing, and attached it to the clock again.

  10. Dro Kulix says:

    I’ve thought of _exactly_ this before…good to see someone’s actually done it. :-)

  11. Captainmogan says:

    taehl, those clocks are available in drug stores now.

  12. Fl3tch3r says:

    I’d be so tired from doing math I would need a nap. Hahaa…

  13. KillerNay says:

    that same as my project in university

  14. KillerNay says:

  15. Gstreng says:

    Wouldnt it be much easier just getting an alarm with a higher volume?


  16. strider_mt2k says:

    Your work is to be commended, seriously.

    However, _large hammer_!!!!

  17. threepointone says:

    man, I’ve been thinking about that! No matter what I do, it seems as if I can figure out how to turn off an alarm clock when I’m half asleep and always end up being late to everything. Gotta try this design. I’d probably need to find some way to mount it so that I can’t actually destroy it, design it to be vibration resistant, and protect the power cord.

  18. techninja says:

    Wonderful! Really great.. we all have trouble gettting up and this would be awesome.. course if you integrated it into clocky you might never want to sleep again

    Hmm.. perhaps a more popular alternative would be to write a flash program for your chumby?

  19. Jack Dalton says:

    Jesus, I have enough trouble doing math AFTER my first cup of coffee!

    At least this isn’t as tough as the average CAPTCHA code these days. :D

  20. Diogo says:

    Why not make change the bed with 2 foldaway legs that “disassemble” and drop you on the floor at the right time ? I constantly run into the problem of sleeping through the alarm sound, so I guess I need a little more feedback from my alarm than just sound ?

  21. ryan says:

    :) would be great to have a switch on the bottom to change the difficulty… spectrum from simple arithmetic to advanced trig…

  22. strider_mt2k says:

    @Jack Dalton: Awesome idea!

    I just read up on the chumby and it’s an interesting platform.
    maybe not 180.00 US interesting, but still really cool.

  23. Peter says:

    Wouldnt a mute button ruin the point?

  24. matt says:

    Timed 120v switch+500 wat halogen work light aimed at pillow+(public school style fire alarm with strobe and big red E-stop button mounted on the other side of the room). works for me.

  25. atomthroat says:


  26. Someone says:

    nice idea but i will just end up killing the thing.

    i think it should be something that gives you a electric shock!

  27. buddy says:

    How about just go to bed earlier so you’re not so tired in the morning?

  28. Don says:

    Can I buy one? This gets to the real issue that I have getting up in morning. Physical activity does not wake me up. Mental exercise, however, does the trick. This is a great idea and well executed with clean and simple design.
    When does this go in to production?

  29. This wont work for me unless the alarm clock is connected to my phone to lockout the calculator feature in the phone while the alarm is ringing.

  30. Eliseo says:

    Informative Article… AWESOME.

  31. mma173 says:

    I thought of similar idea sometime ago.
    I wanted my mobile phone to give me a random number and ask me to put it in. I think it is very easy to modify the software ??!

  32. OnlineClock says:

    Please check out our new Binary Alarm Clock:

  33. Tomé says:

    Interesting idea! I thought of a similar project some time ago, because i too suffer from the “sleepy alarm turn-off syndrome” :) but in my case, you’d have to enter one random number that would appear on the display instead of doing the math. Of course the whole thing would have to be (shock/water/bullet)proof so you could not turn off the alarm by brute force :P

  34. Tycho says:

    The most evil alarm clock ever calls random contacts on your phone until you get up.

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