Sailboat on watch timer

Discussion in 'The Projects Forum' started by kermy, Nov 16, 2012.

  1. kermy

    Thread Starter New Member

    Nov 16, 2012
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    Hi everyone.
    Im new here so be gentle.
    Also new in playing with circuits and for my first project I would like to recreate something similar to this:
    http://www.sailsafely.com/photo_and_guide.htm
    Im not looking to steal his design, just have an interest in learning circuits and figured I could create something usefull as I do.

    Its a simple device that short handed sailors use so they dont hit anyone else (you need to sleep sometime).
    You set a time, and it counts down from that. Everytime you look around you reset the unit and it starts again. Once the time expires a quiet beep sounds for 30 seconds to remind you to look around. If you dont hit reset once the beeping cycle ends a loud buzzer or horn is sounded until reset is hit.

    The easist way I can see to create it is as follows:
    1. Two timers that both start when power is on. The first one lasts the desired time interval (in various periods from 5 to 20 minutes). The second one lasts the same interval plus around 30 seconds.
    2. When Timer 1 ends a quiteish beep (similar to a watch beep) is emitted until reset button is hit
    3. When Timer 2 ends a loud horn or buzzer sounds until reset button is hit.
    4. When reset button is hit the process starts all over by resetting both timers.
    I've read through the basic circuits think I can create the circuit I need for each of the timers but seem to get bogged down when trying to combine them (they both have to work off a single time setting). Im also uncertain as to whether the reset button will work if it is pushed quickly (or does it need to held down).
    I havent purchased anything yet so a nudge in the right direction to get me started would be helpfull.

    Thanks
    Gary
     
  2. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
    785
    Hi.

    Being a sailor myself, I find this very interesting, though I will not need it, 'cause my sailing narrows down to daytrips... :)

    You could do this several ways, but one that pops to mind is with a micro controller. You don't need a big fancy micro with lots of pins and features.

    How many time intervalls do you need?
     
    Last edited: Nov 16, 2012
  3. kermy

    Thread Starter New Member

    Nov 16, 2012
    4
    0
    The time intervals dont really matter but lets say 5 10 15 and 20 minutes (exact time isnt that important). If thats makes things difficult I'd be happy to pin it at around 15 minutes and work to expand it later.
    I forgot to mention that this would be powered off the ships 12 v system which can vary between 11.5 and 14.6 V depending on the state of the batteries.
    Thanks
    Gary
     
  4. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
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    Got an idea with i uC (microcontroller)

    1 pin LED
    1 pin Buzzer
    1 pin Horn
    1 pin RESET / Start timer
    1 pin 4 pos rotary switch

    The rotary switch, along with some resistors, are used as an voltage divider. Voltage is read by the uC's ADC module. According to the reading the correct time intervat is set.

    This might need more thinking... :)
     
  5. kermy

    Thread Starter New Member

    Nov 16, 2012
    4
    0
    Using a iuC might be way above my pay grade.... never tried it though so I wont discount it.

    I was thinking old school and doing something like the pic below.
    2 of these somehow combined to use the same VR and reset button with the second ciruit adding another resistor to make up the extra 30 seconds. Replace the first circuits Red Led with a beep circiut and the second cirucits Red Led with a Buzzer/Horn.
    I wouldnt mind using the 7555 chip for lower power usage but am not sure if a relay would then be required for the beeps and buzzers

    [​IMG]

    (Thanks to unitedelectronics.com for saving me from trying to draw the circuit)
     
    Last edited: Nov 16, 2012
  6. kermy

    Thread Starter New Member

    Nov 16, 2012
    4
    0
    Just did some reading on IuC's
    Very cool
    Instead of hard wiring all the components I can accompolish everything I want by using software and coding output pins for the desired functions.
    I'd lose out on some of the learning experience on circuits but with these chips why does anyone need to learn?
    If I went the IuC route, what should I start with. I'd need a kit that includes software compiler and usb interface.
    Low power consumption is key!
    Thanks
    Gary
     
  7. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
    785
    I'm using a PICKit3.


    Along with MPLAB.

    ... and Hi Tech C compiler...

    I've tried the MPLABX, but I fall back to MPLAB v8, each time.

    Guess others have a different story. :)
     
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