Three Types of Dallas keys – Magnetic and non-magnetic iButtons

A magnetic dallas key is also called a magnetic iButton. A magnetic dallas key (magnetic key in short) consists of a iButton (most common DS1990A+F5/DS1990R#F5), an outer iron ring(iron/Ferrous or stainless steel) and a plastic holders. This type of keys can only work with a magnetic reader with magnets inside.

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Non-magnetic Dallas key consists of an iButton (most common DS1990A+F5/DS1990R#F5) and plastic holder (without the outer rim). Non-magnetic keys should work with non-magnetic reader, with OR without LED should be OK.

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Beside these magnetic and non-magnetic keys, actually there is another type of keys that really have magnetism (with magnetic outer rim). This type of keys consist of an iButton, a plastic holder and a magnetic outer rim. These keys can work with non-magnetic reader as long as the reader has an iron ring for the ground. This truly magnetic keys should work with non-magnetic reader but with an iron outer rim.

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Comparison of three types of Dallas keys

type Non-magnetic dallas key Magnetic dallas key with iron outer ring Magnetic dallas key with magnetic outer ring
Picture Non-magnetic Dallas Key Magnetic Dallas Key with Iron Outer Ring Magnetic Dallas- Key with Magnetic Outer Ring
Constitute iButton

+Plastic holder


+ iron ring

+ Plastic holder


+ magnetic ring

+ Plastic holder

Reader Non-magnetic reader, body can be any metal

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Magnetic reader with magnets inside, body can be any metal

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Non-magnetic reader .body should be Iron or stainless steel with magnetic property

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*Note: iButton and 1-Wire are registered trademarks of Maxim.