![]() Setup for simulating the WWVB signal using a computer-controlled relay (in the Model 100),Ī 30 kHz signal source and a full-wave bridge rectifier. That's what full-wave bridge rectifiers are for! Since this audio generator could produce about 5 volts (at 600 ohms impedance) of nice, stable audio signal at 30 kHz I just needed to double the frequency. Frequency stability is important as the bandwidth of these receivers is just a few Hertz and not only would it be rather tricky to set a free-running oscillator exactly on-frequency, it would also be unrealistic to expect it to stay within +/- 1 or 2 Hz over a period of several days without a bit of extra care. Since the suspicion based on the previous observations was that it seemed more likely that these clocks were "unhappy" with the date with which they were presented and were subsequently unable to set themselves to the correct time, I decided to generate my own local version of the WWVB 60 kHz signal to test this theory.įor a signal source I didn't have handy a synthesized 60 kHz generator (I could have built one, though) but I did have a synthesized audio generator built into a service monitor that could produce a 30 kHz sine wave. The NIST is NOT responsible for this clock's The Augpost - linked here - discusses the construction of an active "repeater" to relay signals from an outdoor antenna to indoor clocks so that they may reliably receive the signal from an LF time station such as WWVB - but it will NOT solve the problem with the affected clocks! If your clock will properly set itself ONCE after removing the battery and replacing it - but it does NOT set itself again, despite the "antenna" symbol, it is a defect in the clock itself!īecause the affected clocks are rather old, it is perhaps unreasonable to expect the manufacturer to "make good" on the clocks' defects, but I would expect that they do know by now the true nature of the defect and would post information accordingly.Ĭomment: This problem may also affect Skyscan models 8675 as well. There have been anecdotal reports by some customers of the affected-model clocks that some representatives of the manufacturer suggest that they are misconfiguring them and/or a change in WWVB's signal format is to blame for their clock no longer working. Collins Colorado.In a previous post - link I commented on how several radio-controlled clocks of one particular model (Skyscan model 86715) seemed to have stopped working properly in the summer/fall of 2012 in that they would synchronize to the proper time and date only once - just after the battery had been installed - but never again. A strong signal from WWVB is required with the clock oriented toward Ft. ![]() ![]() It may be necessary to disassemble the hands and their gear wheels and re-assemble them in their designated order. Others may have more definitive instructions for the "Sky-Scan" clock.ĭuring the getting in sync period, the hands may move in two or three seconds steps depending on the design of the circuits and mechanics. ![]() Then the locking pin removed and the battery inserted, and the clock started to receive the time data stream and allowed to bring the hands in sync with the data stream withing a few minutes. I found in some obscure instructions, a method of "lining-up" the seconds, minute and hour gears to a position where a pin could be inserted through the "stack of gear wheels" to lock the gears, and with the gears locked, the hands could be forced to the proper position. In this way, the whole "musical" group starts out with all the players on the same page of music.so to speak. In the examples I have owned, the hands have to be in a certain position before the battery is inserted. Synchronizing a data stream to the motor that moves the hands is more like the job of an orchestra leader whose task involves keeping the violins, percussion, brass and bass parts all in harmony. I'm not familiar with the "sky-scan" product. The problem is one of the basic design of using a complex radio signal that is a continuous digital stream of month, day, hour, minute and second and using the continuous stream of data to control a miniature battery-electric motor to make the hands go round. Your "atomic clock" is obviously of the analog type instead of digital.
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