Question about Chaney Instrument 66702 Mercury Black Digital Alarm Clock
I have an digital alarm clock (AC 220v) HOSEKI, looks like Chaney 66702, it was a gift from a family member. From very beggining it already runs fast, every day (24 hours) it gains one more minute. Do you have any solution by adding some resistors/diod or capacitor-circuit to make it run more accurate? Appreciate much your help. Thank you. Thanh
I'm not on this field of expertise but I could try giving you some tips. These cloks work by dividing the natural oscilations of a quartz cristal in the corresponding way to form "1 second". A quartz cristal like the one in your clock will oscilate at about 14080236 times per second. Your clock uses a specialised chip in order to count these oscilations and know they form "1 second". However, the problem is the following. These clocks doesn't compensate for frequency variation over the mains power line. You should always look firts at it's power ratings and determine if it requires 50Hz or 60Hz. Even if you use an adaptor to raise/lower the tension from 110 to 220 v or viceversa, this woun't correct the problem as the adaptor will leave the frequency unchanged. Unfortunately in order to make the required adjustments you woun't need a resistor or capacitor, but a whole bunch of them in order to make a frequency divider-convertor that's stable enough to give your clock a fixed time reference. One more thing, not all components have exactly the parameters noted on them. There's another thing called Tolerance. A 1Kilo Ohm resistor with 10% tolerance (most comon tolerance) can have any value with +/- 10% of it's noted parameters, and in this example, could have any value between 900 ohm - 1100 ohm. These clocks will need components with a very strict tolerance in order to have an acurate time reference. Note that they aren't atomic clocks, they simply use a larger chip that includes most of the clock, time reference, frequency analyser and divider. An atomic clock doesn't use quartz cristals, instead it relies on the natural oscilations of the very precise Cesium izotope atom. The rest of the atomic clock is made up in a similar way as usual clocks (more fixed and small tolerance of course :) ).
Posted on Jul 02, 2007
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