Message-ID: <01BEE125.50401890.ed@testelectronics.com>
From: Ed Armstrong <ed@testelectronics.com>
Reply-To: "ed@testelectronics.com" <ed@testelectronics.com>
To: "'lancair.list@olsusa.com'" <lancair.list@olsusa.com>
Subject: Reed Switches
Date: Sat, 7 Aug 1999 22:36:37 -0700
Organization: Test Electronics
Mime-Version: 1.0

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I can vouch for those reed switches Jerry Grimmonpre' recommends. I plan to 
put them on my landing gear and use them as positioning sensors also. I 
field tested them on my car a few years ago on the salty dirty snow and 
slush covered roads in Denver Colorado. I used the reed switches to detect 
the positions of the linkage levers of my manual transmission under my car 
to give a digital readout of what gear I was in. They survived direct 
splashing with saltwater, slush and everything that a road could through at 
them. The only problem I found with them is that they will stick if you try 
to run more than 1/4 amp of current through them. If you keep the current 
levels low below 100mA, they will work fine and last a long time. I 
recommend using the smallest ones you can find so that they only actuate in 
close proximity to the magnet. I also use them as safety interlocks on the 
covers on some of my high voltage test fixtures. I never had one stop 
working, they last a very long time. It is not surprising, they are very 
simple mechanically, there is not much to wear out.

In case your all wondering why I needed a digital readout for what gear I 
was in, I had a remote control start, so I had to have something to make 
sure the car was in neutral before the starter motor kicked in.

Another thing I was thinking of doing was getting one of those little round 
super magnets, mounting it in a ring, and making a James Bond ring that 
unlocks your plane when you position it over a read switch hidden somewhere 
under the composite by the door. Of course any magnet could unlock your 
plane, but they would have to know where the reed switch was hidden. If 
your friends are not all trust worth, you could have a decoy switch that 
sets off an alarm. Or if you wanted to be more true to James Bond, make it 
set off a bomb. Just kidding, have fun building.

Regards,
Ed Armstrong
Watsonville CA.


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