I'm wondering if you can help me with a suggestion for some type of prepackaged sensor to detect metal proximity. Kind of like metal detector except I only need it for small area about 2" square and the distance to metal is ~5mm. But not like metal detectors where I'd like to have just the tips of wires near the detection point.

Here's a picture of that I need. TIA.

 

They are called Proximity sensors, there are many suppliers, some are just ferrous metal, others with detect either.
If you opt for the non shielded type the range is slightly more.'
There is no wires at the detection point. It is done by Hall Effect.
Max.

 

Does the sensor have to have probe wires? What and how thick is the insulation?

And what is the metal that has to be detected?

 

Use an inductive proximity sensor.

 

Have a look too on Ebay.
Search for
Proximity Sensor.

 

A simple Google of "metal proximity sensor" will net a dozen plus hits including inductive proximity sensors. There is also a wide range of AC and DC voltages they can switch. I used the inductive type quite a bit with relays. Anyway a Google should give you dozens of types and vendors.

Well slow on the uptake here and just figured out the Google link was already posted. Thank you OBW0549.

Ron

 

Well slow on the uptake here and just figured out the Google link was already posted. Thank you OBW0549.

I beat you-- for once.

 

Does the sensor have to have probe wires? What and how thick is the insulation?

And what is the metal that has to be detected?

Thanks guys for the quick suggestions. It's been years since I built anything; I'll take a looks at all of your suggestions. The one thing WRT hall sensors (or most metal proximity sensors) that I see (and please correct me if I'm wrong) is that the sensor itself must be close to the metal. I guess I'm looking for some type of remote sensor; sorry if I wasn't very clear in my OP.


Answers to above question:

Yes, I'd like to have the wires so that I can multiplex the sensor onto different pairs (can be any number wires, doesn't have to be 2, I just thought 2 seems "normal") of tips so that I can achieve a higher density/resolution on my 2" squares. Please see picture below.



The metal can be one of lead, stainless steel, or wrought iron. However, if limiting to ferrous or even magnetic can make it work, that's fine too.

 

Oh yes, the insulation minimum is 3mm thick (it would be really nice if the sensing can work to 1.5cm think, but I think up to 5mm is very, very desirable)..

Thanks!

 

The 2" square surface is an example, the final surface can be up to 24" * 24". I'd like to have just one sensor (or only a few) and able to locate many .75" circular plates of metal on that surface.

 

Sorry fhouser.........I have no idea of what you are drawing......or what you are talking about.

 

Is there any reason you cannot place the proximity sensor I mention in post #2 under the 5mm insulation?
You can get them up to quite large distance sensing if needed.
Baluff are one of the larger suppliers of these sensors and have them from 5mm to 100mm
The unshielded 30mm dia will sense up to 15mm.
Is it just ferrous metal?
Max.