Question about RCA RP3721 Clock Radio

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RCA alarm clock - RP3721 - crystal or AC for time?

What does this alarm clock use to keep time? Is it primarily a waveshaping circuit off of the 60hz AC that clocks digital circuit - or - does it run always off of a crystal time keeping circuit? I assume for battery backup, it has a crystal time keeping circuit. If it does use 60hz AC, how does it switch when power may be detected as low? The problem is that every once and a while the clock gains time, but no AC has been lost (as far as observed). Thanks. Larry Park

Posted by Larry Park on

  • chrisalberts Jan 14, 2008

    my clock has run steadily for years, but suddenly started gaining 10 minutes a day. Could a dead battery cause this?

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They used to use crystals to help the timer ics to keep time but since the development of Micropros. all this is built in to one chip. Now they will use a resonator or a small crystal for the timing clock of the micro but nowdays the manufacture uses that clock to keep all in check. If your gaining time you probably are having problems with your ac duty cycle as this also keeps clocks in check.. This would not affect most devices but could be a problem. But of course a defective Micro could also cause this gain in time And probably is?? Now a battery backup is nothing more then a battery in line with the Microproccesors B+ terminal through of course a diode as well as a voltage limiter resistor to take over the B+ when the units ac supply is absent..

Posted on Mar 24, 2006

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My clock is running fast and I can't figure out why?


With the new digital clocks, there is really nothing you can do to fix this. The clock running fast is due to a faulty electronic or electric component that is out of tolerance. US electricity runs at 60Hz, which is 1 cycle per second. Clocks use this to advance the seconds on a clock. Too fast means the 60Hz on the AC power input is not being properly used and is running the clock at something less than 1 cycle per second.

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The alarm display in the lower right corner on model #RC40-A keeps blinking and will not stop. This happens with both wake 1 and wake 2 options. I fixed it once by unplugging the unit but it this did not...


Hello
Just reinstall the battries and adjust the time once again.

Battery back-up operation

* This clock radio is equipped with

a memory holding system that can

be powered with 2 "AA" batteries

(included). The power failure

protection circuit will not operate

unless battery is installed.

* When normal household power

is interrupted, or AC line cord

is unplugged, the batteries will

power the clock radio to keep

track of time and alarm settings

programmed into memory.

* When the battery backup functions,

the digital display will not light,

however, the function of alarm

still occurs during the power

interruption if remaining battery

power is adequate.

* Normal operation will resume after

AC power is restored so you will not
have to reset the time or the alarm

To install batteries:

1* Remove battery compartment door

(located at the bottom of the radio)

by applying thumb pressure to the

tab on battery door and then lift
the door out and off the cabinet

2* Insert 2 AA batteries (included).
3* Replace the compartment door

Replace batteries every year.

Power is fed to the unit even

when it is not functioning. To

cut the power supply off, the
power cable must be unplugged
OK.

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1 Answer

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  • 2 Place your Seth Thomas solar-powered digital clock in front of a light source, such as on a window sill or beneath a lamp. The black strip on the top of the unit is the solar sensor, so as long as light is shining down on that strip, your clock will be powered on and ready to use. The sensor stores energy throughout the day so that it can work at night with no direct light contact on the sensor.

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    Maytag / MAYCOR / Magic Chef / Jennair / Admiral
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