Very low cost? Glue a magnet at the bottom of the pendulum, and below
that install a coil, or a series of coils, or a long curved shape coil
to "pick-up" the magnetic induction. Any low cost op-amp can amplify the
picked up voltage, that will be proportional to the pendulum speed, the
delta-voltage along the time will tells you the acceleration.

Wagner

Peter Keller wrote:
>
> Hi
> I am looking for a lowcost acceleration sensor for capturing the
> acceleration of a 3ft long pendulum.
> Peter