quartz clock driver question/help

Thread Starter

cornishlad

Joined Jul 31, 2013
242
The attached pic is the the small pcb of a (typical?) cheapo quartz clock. The output is 1 pps but the polarity is reversing. I believe it's basically a current drive but the open circuit amplitude of the pulses may be about 150mV. I can't fathom out the relationship between the o/p voltage and and the 1.5v supply.
I's like to use it to drive an industrial style clock that requires alternating polarity pulses of 24v. at about 250mA. If they were simple uni-directional pulses it would be easy to amplify them to 24v... but I can't even start to think how to do it. Any thoughts ?
 

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Thread Starter

cornishlad

Joined Jul 31, 2013
242
With an oscilloscope.. I couldn't get a proper display but occasionaly could seea didplacement that might have been 3 divisions 50mV..
 

Thread Starter

cornishlad

Joined Jul 31, 2013
242
That seems a rather low voltage.
Exactly between what two points did you measure that?
you were right to doubt crutshow, I'm a dumbass.. Forgot the probe was 10x att. So the pulses are battery voltage likely outputed from an H bridge. I guess the output connections (where the stepper coil was connected) are open circuit between pulses ?
 

Thread Starter

cornishlad

Joined Jul 31, 2013
242
Progress...A plan is evolving.. I've determined that positive going pulses of 1.5 v(relative to the 1.5 battery -ve) are outputing alternately from the two conection points that previously fed the stepper motor coil.
I could convert these to 5v logic level with a dual comparator LM393. These could feed a small chinese H bridge fed with 24v from a Chinese step up converter..
I should have put "I think" in front of all those. Does this seem workable ?
 

Thread Starter

cornishlad

Joined Jul 31, 2013
242
Because of the helpful suggestions received I think/hope this diagram will work ?clock cct copy.jpg
Actual progress has stalled after my test to see what voltage the quartz clock pcb would work up to. It expired at +4.5v :-(
I am seeking a replacement..
 
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