Dividing circuits

[John Craig]

I am building a free pendulum clock, and am hoping to get pulses at
the rate of one per second from a photoelectric cell in the path of
the pendulum.
Where can I find a circuit which will count these, and give out a
signal after 30 pulses?
This would be used to drive the clock hands, and also power a magnet
to keep the pendulum swinging.
Thanks for any help,
John

 

[Terry Pinnell]

I am building a free pendulum clock, and am hoping to get pulses at
the rate of one per second from a photoelectric cell in the path of
the pendulum.
Where can I find a circuit which will count these, and give out a
signal after 30 pulses?
This would be used to drive the clock hands, and also power a magnet
to keep the pendulum swinging.
Thanks for any help,
John

This should do what you want:

http://www.terrypin.dial.pipex.com/Images/Pendulum-Divide30.gif

Choose mono RC values to suit your needs. Drive next stage via
transistor or relay as appropriate. Supply can be 4 to 16 V.

 

[Jasen Betts]

I am building a free pendulum clock, and am hoping to get pulses at
the rate of one per second from a photoelectric cell in the path of
the pendulum. Where can I find a circuit which will count these, and
give out a signal after 30 pulses?

there's a milion different ways to do that... a small microcontroller could
be programmed to emit a pulse evert 30 clock cycles, or you could build a
divider from discrete logic... (eg a couple of decadee counters in series
the first wired as divide by 3 the second as divide by 10) or set up a 29.5
second monostable triggered by the pendulum - every thirty seconds the
pendulum will re-synchronise it.

Bye.
Jasen