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MarkAren

Jan 1, 1970
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Hi All,

I recently acquired an inductive proximity sensor designed for
industrial applications.

The unit has two terminals and runs on 10..55V DC.

All you need to do to connect it up is place a load (relay etc) in
seres then apply power.

The interesting property is that wired one way around the unit is
normally open (apply a metal plate to the sensor and it switches on).
Wired the other way around and the unit is normally closed (apply a
metal plate to the sensor and it switches off).

The unit claims a maximum dropout of 2V.

This poses some interesting design issues:

My first inclination was that the terminals of the unit went through a
full wave bridge before the drive electronics. This won't work, you
have just lost 1.2V across the bridge and I doubt if you can run the
electronics on 0.8V.

Second thought was that there are two complete systems within the
unit. One for the 'positive' polarity (NPN) another for the 'negative'
polarity (PNP). Each system is designed with opposite output drive
sense.

Anyone have any other thoughts on topology for this device ?

See http://www.ifm.com/ifmuk/web/dsfs!IM5038.html

Regards,

Mark
 

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