On a quartz clock made in the 1980s, why did it need a (+ -) fast slow adjustment knob?

Any quartz clock that you have from the 1980s would have a (+ -) symbol on the back and a screw to either turn right for slow or left for fast.

Why did quartz clocks back in the 1980s need a fast slow time adjustment knob?

Update:

If you look at a quartz schoolhouse Westminster chime clock from the 1980s, the quartz movement is bulkier and contain a fast slow + - screw adjustment knob. On some quartz schoolhouse clocks they literally use the pendulum as the time adjustment piece. 

I'm serious this is a quartz time piece. 

3 Answers

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  • 3 weeks ago
    Favorite Answer

    The quartz crystal that times the clock had a small low value 'trimmer capacitor' to fine tune the clock. Modern clocks don't need that.

  • Anonymous
    3 weeks ago

    Have never seen that . . . . have had lots of those clocks with little battery movements from that period - with an adjustment - but they are old school, not quartz.  None that are quartz have an adjustment.

    Will stay tuned for info from other users.

  • Anonymous
    3 weeks ago

    One thing that affects the accuracy of quartz is temperature. So if you were in a hot room or a cold hallway you need some way of compensating for the temperature variation. The other is age, the frequency decreases the older a manufactured crystal gets.

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