One Second Timebase.

Here are the instructions how to get one-second (1hz) pulses from a broken quartz clock. This is a precision timebase generator that can be used in any project that needs exactly one-second pulses. (6/11/2006) Updated!


Usually quartz clocks breaks easily (specially if these are made in china) after a while. The gears lose lubrication and the dust gets the job done. Fortunately, the electronics of the clock works for many years without problem, so you can "hack" a quartz clock to get a timebase generator.


quartz clock Here is the "victim". A clock can be purchased for only $4.00 USD; sometimes it can be purchased for only $1.00 USD.


opening the quartz clock quartz clock gears inside The clock mechanism only has three clips and can be open easily.


You can save the gears; it may be useful in the future.


quartz clock electronics Here is the part that we are looking for. The timebase generator.


quartz clock dissasembled. As we don't need the coil, we have to remove it. Remove it carefully; it will be used for a future project.


How to hack a quartz clock schematic This is the modification that needs to be done. We need to diodes (1N4148 works great) and 1k resistor. The resistor will reduce the current so the circuit can work from three volts to five volts.


timebase generator from a quartz clock one second generator. Here is the circuit with the modification. The photo shows the two diodes and the 1k resistor can be mounted in the circuit board.


The right photo shows the circuit under testing. I used 3 volts and one led. The led blinks exactly one time per second.


Here is an explanation how the quartz clock works:


how pulses are done on quartz clock.


As you can see, the circuit generates a pulse every two seconds on each connection of the coil, it makes the round magnet to turn half cycle for each pulse. So, using diodes adds each pulse to generate one hertz. (1 Hertz = One pulse per second.)


12/31/2007 - Update: Thanks Adam D!
Instead of thinking where to party this end of the year, I was thinking how to improve the "One Second Time base" circuit.


Here are two possible modifications for this project. Some "Made in china" clocks are getting even cheaper, so cheaper that actually, "Quartz" clocks are made with Ceramic resonators instead of Quartz crystals.


Ceramic resonators are affected by voltage, temperature, and, I believe, vibration. Because of this, the above circuit will not work as the clock circuit receives more than 1.5Volts, so here is the solution:


one_second_II.gif One second time base circuit The first circuit uses an additional LED. The LED works like a regulator and limits the voltage that the clock gets. The voltage for Red LED is about 1.8V. The infrared LED has a voltage of 1.6 Volts, so an infrared LED works fine for this circuit. The output will be approximately equal to the LED voltage. (Is not easy to measure the voltage of pulses, so I'm guessing).


If the circuit that you are planning to drive with the one-second pulses doesn't work with the output voltage, you can use any PNP transistor so the voltage will be good enough.


This circuit can use up to 12 Volts, but I do recommend to use it for only 5 Volts as it is compatible with TTL circuits and 5 volts can be obtained from an USB port.


Basically, to make this modification you need these additional parts:


  • 1 Infrared or Red LED.
  • 1 1K resistor.
  • 1 PNP transistor.

    I hope you have a great 2008 full of blessings, especially for those people that really need it.


    March 2nd, 2014 - Peter Zoch wrote:




    many thanks for your clock circuit. I have used it with arduino to provide it with accurate clock signal. Your IR diode calculations were OK, I feed the clock with approx 1.19V using IR diode an 1K resistor. Nevertheless, your diode calculations were a bit underestimated. They were blowing after few minutes of operation constantly. I don't have an osciloscope but my assumption is that the clock circuit must drive the "motor" coil with quite of peaks to move it. I have replaced them with 1N4007 and they work just fine :) I have used NPN instead of PNP to be able to use arduino digital input from the clock. All works A+ with these modifications.






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