proximity induction sensors

[jhead]

Does anyone know of a good source for inexpensive smaller proximity
induction sensors.

My application isn't very high end - I just need to sense when a steel
ball is over a certain spot in a plastic tube.

Also, is there any thing I could salvage the components from, or
perhaps get from a salvage dealer - automotive perhaps?

Thanks.

 

[Jamie]

Does anyone know of a good source for inexpensive smaller proximity
induction sensors.

My application isn't very high end - I just need to sense when a steel
ball is over a certain spot in a plastic tube.

Also, is there any thing I could salvage the components from, or
perhaps get from a salvage dealer - automotive perhaps?

Thanks.

Small Proxs need to get closer to the object.
You didn't specify the size of the tube?

My guess is that what ever you decide to use that
is already out there, it's going to cost you!

Construct a U-Core xformer with the primary and
secondary separate wound on each outer section.
allow for the tips of the core to be exposed so that
you can place the plastic tube between the tips/
insert a low freq osc into one coil and detect the
signal on the other coil.
when the steel ball passes between the U-fingers, the
signal output on the output coil will increase.

Also, one could use a single coil and detect the
induction value change..
etc.

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