Can I get the 1 hz pulse out of a wall clock movement to time a digital clock?

 

Should be able to tap off the solenoid pulse if its a battery powered one.

 

Hello,

That depends on how the wall clock is made.
Many use a 32768 Hz crystal.
Find the signal, amplify it and divide it by 32768 and you will have your 1 Hz timebase.

Bertus

 

You can count a 16 bit word with it starting from 0x8000, and when it overflows, that’s your 1 Hz interrupt.

 

If your clock is AC powered, divide the line frequency by 50 / 60 and you got it.

The long term accuracy will be better than any crystal oscillator.

 

While a battery-run wall clock is one source, a DS3231-based real time clock (RTC) module will give you a very stable 1 Hz clock pulse. Such modules are <$2 USD and even less if you buy more than one. Here is one source:
http://www.banggood.com/DS3231-AT24...al-Time-Clock-Module-For-Arduino-p-81066.html

You can also get a 32.768 kHz pulse and several other frequencies in between.

John

 

Can I get the 1 hz pulse out of a wall clock movement to time a digital clock?

If you are talking about the type pictured below and usually available on a clock available from Goodwill or Savers stores as used for $1 to $3, absolutely!

Accuracy may be off 1 or 2 seconds per day but pretty darn good for most applications. Nice strong pulse every second to power the solenoid (usually a gold-tone silicon-steel plate with an eyelet to rachet the gears of the clock mechanism. You can just tap into the non-grounded lead of the solenoid's coil and connect our circuit's ground to the clock ground. It is likely easiest to keep the clock's battery on the clock instead of using system power for the clock.

 

Per GopherT's suggestion, I've used gutted 1.5V battery clocks for 1Hz clocking. Some wall/desk clock use pullup on the coil outputs. Some use pulldown. Attached are two configurations I've used.

Ken