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What crazy people do with their spare time — Parallax Forums

What crazy people do with their spare time

Martin HodgeMartin Hodge Posts: 1,246
edited 2010-08-27 14:39 in General Discussion
I think every electronics hobbyist has, at one point or another, built the obligatory digital clock of some sort. As a lifelong closet horologist (who's a bit nuts) I've always wanted to see how far I could push the limits of usefulness and good taste. I think I'm making great strides. Introducing "Big Ned". A two foot high digital clock using Parallax CCFL lamps, An SX48 proto board, an old GPS receiver, 21 MOSFETs, and a 5 amp switching 12v power supply. The firmware is written in SX Assembly. In the pictures below I don't have the GPS antenna connected so it's doing the 12:01 dance.

Things still todo. Some kind of contrast screen across the front and conversion to a Propeller chip. (There's just too much 32bit math going on for an 8bit uC)
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Comments

  • ercoerco Posts: 20,260
    edited 2010-08-26 08:20
    SWEET! Great use for the CCFLs!

    I'm a mech horologist, I have a dozen wind-up and weight-driven clocks all perfectly sync'ed up to chime at the same time. Grandfather clock, 2 cuckoos, regulators, etc. That's the mech engineer in me!
  • WhitWhit Posts: 4,191
    edited 2010-08-26 09:12
    Martin Hodge said...
    Things still todo.

    Don't forget temperature! :lol: Great project! This is probably more useful than what most crazy people do with their spare time...
  • David BDavid B Posts: 592
    edited 2010-08-26 09:33
    Can't the SX keep time when the system is off GPS, then sync up when GPS becomes available?
  • Martin HodgeMartin Hodge Posts: 1,246
    edited 2010-08-26 10:49
    David, the SX is perfectly capable of keeping time by itself, but the bum programming it has to get around to getting it done. This particular GPS unit doesn't output date info in it's NMEA sentences, so I had to parse the raw binary data and convert 48 bit floating point numbers to H:M:S Y:M:D. The reason for that is to calculate automatic DST adjustment like WWVB provides. Doing all that on an 8bit uC is too insane even for me, but not impossible. A more expensive modern GPS module would be a breeze, but where's the fun in that?
  • Martin HodgeMartin Hodge Posts: 1,246
    edited 2010-08-26 10:59
    erco wrote: »
    I'm a mech horologist, I have a dozen wind-up and weight-driven clocks all perfectly sync'ed up to chime at the same time. Grandfather clock, 2 cuckoos, regulators, etc. That's the mech engineer in me!

    Don't forget antique pocket watches! What marvels of mech engineering those are.
  • John R.John R. Posts: 1,376
    edited 2010-08-26 11:03
    erco wrote: »
    SWEET! Great use for the CCFLs!

    I'm a mech horologist, I have a dozen wind-up and weight-driven clocks all perfectly sync'ed up to chime at the same time. Grandfather clock, 2 cuckoos, regulators, etc. That's the mech engineer in me!

    You should do like my Grandfather did with his coo-coo clocks. He staggered them slightly so that they went off one after the other, instead of all at once. The "clock room" normally had the door closed.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-08-26 11:56
    erco
    Is this what your place looks like? :-)

    http://www.youtube.com/watch?v=r9LB7ez99T0
  • ercoerco Posts: 20,260
    edited 2010-08-26 13:27
    Yes, yes, and yes! Pocket watches are cool, and REPEATERS are the coolest. Wish I could afford one. One day, after I launch my commercial robot (yes!). Repeaters (pipe down, ham radio buffs) are chiming pocket watches and are the ULTIMATE in micro-mechanical precision. http://www.antique-pocket-watch.com/repeater-pocket-watch.html

    But lately, I have settled for a more affordable timepiece which combines two of my interests: http://cgi.ebay.com/Silver-Robot-Necklace-Pendant-Clock-Pocket-Watch-Box-/250685511267?pt=AU_Watches
  • K2K2 Posts: 693
    edited 2010-08-26 14:29
    Martin, you are really a glutton for punishment! GPS modules are incredibly cheap. Save you a ton of effort.

    I've implemented Zeller's Congruence any number of times, but have not processed the raw binary from a receiver and don't plan to.

    BTW, I love your clock!
  • Martin HodgeMartin Hodge Posts: 1,246
    edited 2010-08-26 14:54
    K2 wrote: »
    GPS modules are incredibly cheap. Save you a ton of effort.

    The modules I bought were $10 ea.

    I misspoke when I said raw binary. I meant the Rockwell proprietary binary format which is just one step removed from NMEA sentences. I'm still letting the GPS module do all the heavy lifting. I needed to learn how to handle floating point math anyway, so I gained many wrinkles of brain tissue in the process.
  • RavenkallenRavenkallen Posts: 1,057
    edited 2010-08-26 19:37
    Who doesn't want a two foot clock? Nice work, man.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-08-26 22:30
    I wonder if there is a way to use a cheap plastic digital
    watch? You can sometimes get one for a dollar or
    so. The ones for girls are pretty small and the circuit
    must be very tiny.

    Maybe there is a way to get the time data out of the
    watch circuitry.
  • ercoerco Posts: 20,260
    edited 2010-08-27 11:14
    Good call, Holly. I have built projects that triggered off the hourly chime of a digital watch, for hourly activation. Even cheap watches are fairly accurate. You could even use a BS1 as a clock, using pause statements to rough out the time, and it would get corrected every hour by the watch chime.

    I also bouught a $5 talking watch off Ebay that I plan to build into Wastebot. It is already set to speak the time hourly, like a chime, plus you can wire a simple reed relay to trigger the "speak time" function anytime you like.
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-08-27 14:39
    Holly I have thought on making a watch . from scratch ( gates ). but I ran out of time at my old college to make it .
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