dannyk
After 2 years of looking at the window alarm sensor and saying "wonder what that thing does?", my team asked me to "find someone smart" and ask. I get no respect. But they are right. Can anyone explain potential BEST uses or refer us to a good reference. It seems sort of like a limit switch but I know we are missing something.
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jgraber
Hi dannyk,     yes the MDAS (magnet door alarm sensor) is like a limit switch, and it doesn't get used much.   Often new parts need to be essential to a highly successful robot at hub and regional competitions before they catch on.
   MDAS consist of two pieces,  a magnet, and a magnetic reed switch.    Like a NLS (normal limit switch), MDAS just conducts or does not conduct,  so it is connected between ground and a digitial input pin.   You can use it as a replacement for a NLS in many limit switch applications.
   MDAS is better different from a NLS because it does not require physical contact;  so there is no drag on a moving part, no bending of the lever, no stress or wear on the lever part of a NLS.  Because it is encapsulated in plastic, it is more rugged and robust than NLS.   You could use a MDAS as both a physical stop as well as a limit switch.   MDAS is also much quieter.
    MDAS is worse different from a NLS because it only detects a magnet, and there is only one magnet provided.  If you use MDAS as a rotation counter on a wheel, it can probably only click once per rotation, whereas a NLS could be clicking over a bunch of 3d printed bumps to get higher resolution.   All that clicking noise from NLS would be annoying, but at least you can hear it during development and debug, unlike the quiet MDAS.
    Brainstorming ideas for other applications:
- Can a coil of cat5 wire on a digital output be used to trigger the reed switch?  
- Can a magnetic shield with slots in it, moving between the magnet and sensor, be used to get many clicks?
- MDAS is good for a delicate mechanism, like a clock pendulum, where the physical drag of NLS would be harmful.
- Previous game 'Total Recall' had some magnetic parts, for which the MDAS could be used as a sensor,  but a nut on a string worked better as a visual aid to detect magnetic parts.
   Does your team have any brainstorm applications to add?
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dannyk
Thank you. These are some interesting projects for the programmers.
They have not done any brainstorming yet, but this will give them a great start. I'll try to report back.
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