16 thoughts on “Cheap 1 Hz Clock Source

  1. That is clever!

    A few years ago I was considering making a series if flashing IR beacons to be dropped by my wheeled ROV as a “trail of breadcrumbs” low-tech system to help me navigate the ROV back to my home using cameras on board the vehicle.
    This application would be great for something like that!

  2. The beacon idea is really silly. But the hack seems nice. This is the kind of projects this website needs! It’s:
    -easy to rebuild
    -useful in many projects
    -relatively harmless
    -not so easy that everybody already had that idea
    -a hack instead of just a stupid mod
    Unfortunately it’s not new. Well…

  3. I dn’t really see the use, unless you happen to have a clock lying around at home.
    This can be achieved pretty easily with an opamp (50/50 duty cycle) or a 555 (Any duty cycle)
    I don’t really see the use of a quartz precision 1 Hz clock source.
    But on the other hand, if you have the parts in your hands, why not.

  4. A pretty good use of a precision 1Hz clock source would be if you are building a digital alarm clock, or any other device that you would like to keep accurate time over long durations, like a datalogger, etc. Even an error of as small as 0.07% corresponds to a minute a day gained/lost, so it’s pretty easy to see how badly a 555 would do in that situation.

  5. #9: That’s what he did. He took the quartz clock out of a cheap watch and rewired it to provide a pulse every second to his circuit (which is what the quartz clock does in a watch, so he basically just stripped it down and hacked it into a new circuit, neat).

  6. Actually he used a full sized clock.

    An analog wristwatch should work fine, although you might need to use a small npn transistor to get enough current to run a LED. Don’t even think about trying to use a digital…

  7. It’s actually possible to drive ttl with this unit but don’t use the actual output since it’s only about .3 to .9 volts with a 5 volt input. You need to get a clock with an alarm… the dollar store has them. now using the same circuit, unsolder the small buzzer noting down the polarities, connect a zener diode on the plus side and connect the other end to a 100 ohm resistor added in series to the 1K resistor, now there is an extra leed in the PC board to control the alarm
    it is activated by connecting it to the negative of your 5 vlt DC. that gives you 6 controled pulses a second at 4.3 vlts dc. Now that, connected to a 4 bit couter like the 74ls393 will hold a steady output. Use a differant power supply for the ttl to avoid resonnance. Pictures of unit available on request.

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