I need to presence sense a row of several magnets (6-20, depending on the machine size) that are repeatedly placed onto and collected from a steel surface. I need to determine a "signature" of the magnetic field of the group, then check each time they are placed/collected to ensure that none are missing. Thought is to run a strip of the desired material close alongside the row, and check the resistance (signature) with an ohmmeter.
I'd also be interested in any other ideas to accomplish this.
Thanks in advance!
2007-07-31 07:38:33 · 3 answers · asked by tornwax 3 in Science & Mathematics ➔ Physics
I forgot to mention that these are permanent magnets.
2007-07-31 10:15:51 · update #1
depending on the strength of the magnet i don't know if you will be able to detect an identifiable difference in resistance say per one missing. but if they are placed repeatedly in the same pattern you can put reed sensors that will close every time there is a magnetic field close enough now i don't know if the magnets would be to close for that were as they wouldn't set off all surrounding sensors but its an idea. Plus these sensors are easy to find and are relatively cheap. i would like to no if you get the resistance idea to work just use a low resistant metal like copper or brass
2007-07-31 07:53:37 · answer #1 · answered by nato 2 · 0⤊ 0⤋
A magnetoresistive sensor does that. It is similar to a technology used in the recording heads of some modern disk drives. It might not be the best way to solve your problem. Consider also a reed switch. Or a pressure-sensitive pad between the steel surface and the magnets.
If money is no object, use a SQUID.
2007-07-31 22:41:22 · answer #2 · answered by Frank N 7 · 0⤊ 0⤋
Not resistance, but impedence. The impedence of an iron-core coil will drop when the iron reaches its magnetic saturation point. You can sense the change by measuring the current in an a/c circuit.
2007-07-31 15:36:50 · answer #3 · answered by Anonymous · 0⤊ 0⤋