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how to make a reed switch for sensing a magnet from 4 to 5inch distance? or a substitute with RF Answered

pls guide,
that i want to know the way to make a reed (in DC) have to sense a magnet from a distance of 4 to 5inches.
did small reed will act so ?? if a yes, then which specification have to look??

or did there any circuit or something for making it much more powerful??


7 Replies

steveastroukBest Answer (author)2014-07-01
shinojmahe (author)2014-07-08

Ohh, the i am planning for some thing, let me share;

transmitter and a receiver (or a tag, but i don't know that tern exactly :( ), very small in size, power will be from button
batteries, also on the receiver, i have to fix one LED, when the
receiver finding the transmitter, this LED should ON on Transmitter..whn it is away, LED
will be off.

the distance is same, approximately 5 to 6 inch or so.

could u guide me pls??

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shinojmahe (author)2014-07-02

seems this will be best for my purpose.

Hall Switch, let me find the differences among Haal effect switch and Reed Switch

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Josehf Murchison (author)2014-07-01

Yea big magnet really big magnet.

If you tell us what you are trying to do we might be able to give you a better answer.


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mpilchfamily (author)2014-07-01

From 4 or 5 inches away even a HDD magnet has trouble moving the needle of a compass. The pulling force of a magnet drops off rather quick the further you get from it.

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verence (author)2014-07-01

4 to 5 inches? A reed contact? Two words: No. Way.

4 to 5 Millimetres - yes. Twice/thrice that - possible, with a strong magnet.

What do you want to do? A magnetic field is just not strong enough.

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FarmerKJS (author)2014-07-01

use a harddrive magnet or any other super strong magnet of print one on this thing


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