Gentle wake up alarm

[Michiel], unsatisfied by his Phillips wake up light, decided just to make his own. He really wanted programmable weekend alarms as well as an easier to find snooze button. At first, his circuit was not reliable enough, losing several minutes per hour, but he gutted another alarm for the 1Hz crystal. After some carpentry, his final alarm ended up quite nice.  After so many aggressive alarm clocks, it’s nice to see that not everyone needs to be assaulted out of bed.

Correction: apparently, there’s no 1Hz crystal. That was a guess on my part. -[Caleb]

[via Hacked Gadgets]


  1. Michiel says:


    I’m always commenting about the Arduino project, so I thought that it would be nice to show one of my PIC based projects.
    Note that I call it the Noduino…, LOL

  2. DougBoy says:

    Is that Mythbusters?

  3. Agent420 says:

    I don’t believe 1hz crystals exist… the aforementioned timing source is commonly produced by the ac line frequency in alarm clocks.

  4. Dustin says:

    @DougBoy i thought so, too haha

    and on topic. very nice build.

  5. Fallen says:

    @ Agent420


    Anyways there is a common crystal used in cheap watches, that when divided by some number, gets you a 1Hz clock. But as far as I know, most alarm clocks use the AC line for their timing.

  6. Ben Ryves says:

    Nice project. :-) 32768Hz seems a common crystal frequency for real-time clock circuits, and being a power-of-two is easy to divide to get a 1Hz clock.

  7. j says:

    I’m def one of those guys who needs a aggressive alarm clock. The best would be sensors in your bed that make it so it won’t stop ringing until you actually get out of bed. Sometimes I manage to get out of bed, turn off the 4 alarms on my cellphone and the two on my alarm clock then go back asleep with out remembering. a cool feature would be adjusting the loudness according to how badly I need to get up.

  8. redbeard says:

    Michiel, i’m just as impressed by the case for your V-amp.

  9. panicopticon says:

    I do something similar, though in a much less fancy way. I have a flexible desk lamp with an old CFL in it pointed at the ceiling. The desk lamp is plugged into an mechanical light timer set for about half an hour before my alarm goes off. Since the CFL is old, it takes a while to warm up, so its like the sun rising. On days I don’t want it to turn on I leave the switch on the lamp off. A bit Rube Goldberg, but it works.

  10. Michiel says:

    That is the mythbusters.., lol, well spotted. :P

    And I don’t use a 1Hz crystal, I just got a nice 1Hz signal from the original clock pcb.
    The original clock gets his timing from the 50Hz AC mains frequency.

    @ Redbeard
    That is a other ‘little’ project of mine.
    It got a 100Watt Celestion guitar speaker and a small 2×30 Watt bridged amp, sound amazing.

    And thanks for all your comments! :)

  11. LuciusMare says:

    Great, and just in case it would not wake me up, let’s wire it to me and turn on the power >:)

  12. Michiel says:


  13. googfan says:

    since when is there a 1hz crystal?

  14. wdfowty says:

    read the comments before yours

  15. HackJack says:

    Maybe it is just me. I think all wake up alarms relying on wall electricity is a failure. Unless it has a backup battery which I doubt. All it takes is a short power outage and you will be confronted with the blinking 12:00.

    On a related note, I find cell phones great as an alarm. Most of them has calendar function.

  16. Hal says:

    @Michiel: Does the bulb fade on? Or is is just on and off?

  17. XBMC^N says:

    My first microcontroller project (well, first after the immensely satisfying “hello world” blinking LED) was a clock with an LCD display, and like this guy, I tried to use a controller with an internal oscillator.

    It was a hilarious failure. Accurate to +-10 minutes / hour, and ran for no more than 4 hours on a fresh 9 volt battery.

    It doesn’t get used as a clock anymore. These days all it does is tell me what command codes are being sent by various infrared remote controls.

  18. DarwinSurvivor says:

    Been working on my own timer project for a while (times SoapBox cars going down a hill). Does anyone know if there are any common crystals that will put out a number easily dividable to either 1KHz or 10KHz? I know how to build it with a 555, but they are notoriously bad for time-creek, especially in changing temperatures (event is outdoors).

  19. Rupert Merdock says:

    LOL 1Hz crystal. I sense a decline in the quaility of HAD admin.

  20. r says:

    why don’t you cross-out “1hz crystal” in your post and replace it with the correct way (instead of adding the correction at the end)

  21. RoboGuy says:

    Yikes, is that an incandescent? Might want to change to CFL.

    Not because of the eco-friendly stuff, but because burning your hand when you hit the light instead of the switch has got to be painful.

  22. mike says:

    @RoboGuy: That’s part of the alarm! Burnt fingers = wide awake…

  23. Jawn Dough says:

    Caleb….honestly, 1 hz crystal? Do you actually know anything about electronics?

  24. jwt says:

    I echo the comments here that Caleb is a total n00b

  25. elphreaker says:

    Is the SSR controlled by PWM?

  26. moere says:


    this alarm clock is no wake up light anymore,
    is it?

    The light bulb is just turning off to on.

    A real wake up light fades from off to on slowly.

    But nice work!!


  27. Message above by ‘j’ – “four cell phone alarms & two normal alarms and still goes back to sleep” made me laugh aloud.
    At least you get up to turn them off.
    I know someone who would sleep through the ruddy lot, leaving me to chase around finding them ;-)

  28. Michiel says:

    LOL.., guys!

    You can remove the “[via Hacked Gadgets]“, I mailed you first… :P

  29. Dennis says:

    Oh geez… To make a 1 Hz crystal you’d need to, like, find a mountain made of quartz and bury some electrodes in it…

    I know the error has been pointed out already but the mental picture you get if you know how to do the math is so hilarious:

    According to wikipedia “The thickness of the quartz blank is about (1.661 mm)/(frequency in MHz)” (for the most common type of crystal cut). Calculating 1.661mm/0.000001, you would need a crystal 1.66100 kilometers thick.

    Now, can anyone calculate how much POWER you’d need to oscillate that crystal?

  30. Rectifier says:

    I was going to build something like this (but dimming) for awhile but came up with a easier solution using cheap off the shelf hardware.

    I set up my wake-up light system using an X10 wall switch/dimmer module and X10 USB interface.
    The X10 dimmer can be remotely set to arbitrary values, and I have the system ramp up my bedroom lights (150W halogens) over 30 minutes in the morning. The whole thing (along with the other house lights) is just controlled with cron and some simple perl scripts.
    A bonus is that you can’t snooze it (if you turn the light off, it will come back on when the next SET DIM comes in in about 30 seconds) so I have to get up.
    I also have it dim the lights down when it’s time for bed on work nights.

    The only thing missing is there isn’t quite enough blue spectrum to wake me up completely, like the sun does. I’ve thought of mixing in some of those horrible CFLs but you can’t dim them – and I hate the light

  31. error404 says:


    If you’re going to throw in a microcontroller anyway, the frequency of the clock isn’t very important as long as it’s high enough to give you the timing resolution you need. You can generally use the internal timer/counter hardware to count clock cycles and derive your timebase from that. For example if you have a 10MHz crystal, you can set up a /8 prescaler to get 1.25MHz in the counter. Use an 8-bit counter set to fire an interrupt and reset at 124 and you’ve got yourself a 10KHz interrupt.

    Another approach for your sort of timing application is to let the counter free-run but interrupt on overflow. Use the overflow to maintain a software counter, and stop the counter based on your external timing interrupt. The software counter are your MSB and the timer value the LSB.

    You should use a TCXO or OCXO for any kind of timing application.

  32. moere says:

    @ Rectifier

    could you give me please a link to such a
    “X10 wall switch/dimmer module” ?

    I am planning on building a wakeup light.

    Using a dimmer is a great idea.



  33. Forrest says:

    There are other cuts of crystals then … try plugging 32768hz into that formula. :)

  34. GSV Ethics Gradient says:

    I use a 400W floodlight and an off the shelf plug in timer.

  35. DarwinSurvivor says:

    @GSV Ethics Gradient

    Make sure to sleep in different positions each night so as to even out your tan!

  36. rain says:

    tv show lost clock

    is the best wake up sound!!

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