On Fri, Jun 17, 2011 at 1:27 PM, Xiaofan Chen <xiaofanc@gmail.com> wrote:
> Typical design is to use a SCR or IGBT. Actually all the 2-wire AC
> proximity switch work like this from what I see. I worked for
> Pepperl+Fuchs before and it has quite some such AC sensors.
> Same for Omron, SICK and other sensor vendors.
>
> An example: Inductive sensor NBB2-F1-US.
> http://files.pepperl-fuchs.com/selector_files/navi/productInfo/edb/188298=
_eng.pdf
> You can see that it actually works from 20 ... 253 V AC/DC
> Within this type of sensors, there are of course lower
> voltage based circuit (say 5V or 3.3V MCU or =A0others -- I think there
> are no MCUs in this particular sensor but there are others
> which may have one).
>
> Whether this will work or not depend on the load.

Just another datasheet which shows the block inside the sensors.
http://www.yamatakeusa.com/pdf/aaaa/CP-2131E.pdf (AC FE8V).
When the sensor if off (SCR is off), the main circuit
(mainly an oscillator and an comparator) should
consume low current. When the sensor is on (SCR is
on), the ON voltage of the SCR should still be able
to sustain the main circuit.

> But if you follow the design, maybe you will have to
> combine the AC switch into your design.
>

--=20
Xiaofan

--=20
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