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Bulbdial Alarm Clock

edited August 2012 in Clock Kits
I have an assembled Bulbdial clock that works perfectly, however I need to add an alarm. Where should I connect it? I'm thinking of connecting pin 17-19, 9, or 10 (the ISP pins, or crystal pins[since I have a Chronodot]) to a transistor to power the alarm. Additionally, what sort of speaker should I use?
Thank you


  • One thing to consider is how you're going to reprogram the clock to take advantage of the speaker.  If you're going to use the USB-serial interface, then repurpose the ISP pins.  If you're going to use the ISP interface, repurpose the serial pins. 

    The crystal *is* used by the Bulbdial. So, if you want to run without it, you'll need to reprogram the chip with an ISP interface (to set the fuses to run off of the internal timebase), and likely make other changes to the programming as well.

    The Alpha Clock Five and Meggy Jr RGB kits use a little magnetic speaker/buzzer for their noises and alarms.  It only requires one pin from the MCU (plus a transistor) to drive it.  That type is likely a good choice.  Use the contact form on our web store if you'd like to buy one from us.
  • Thank you.  If I reprogram the chip to use the internal timebase, can I still program it in Arduino after that?
  • Yes, see some hints about how to modify Arduino to work without a crystal here:

    Generally however, I would recommend sticking with the crystal and putting the speaker elsewhere; you only need one output pin to do it.
  • Thank you for replying so quickly, I will use the ISP's MISO pin for the speaker, as you have done for the 8th row on the MeggyJr's rgb matrix (I don't have an ISP anyway).
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