Chip writes:
<< I'll take a look sometime this weekend. Maybe Tim
Hughes knows if there is a small enough, high quality
NC magnetic switch available for this purpose.
>>
Chip,
The most common reed switches are NO not NC. I have not seen any
really small NC. switches but I have not looked for any. Try the online
electroncs catalog suppliers like Allied,Radio Shack,NTE,Jameco etc. Surplus
stores often carry boxes of reeds at low cost. For example in the Bay Area
Halted (which also has a partial web catalog) and Alltronics (also web)
usually have reeds. Small reeds are often about 12mm long by about 2mm diam.
. Change over reed switches maybe the easiest to get for this purpose, but
the ones I am familiar with are often a bit bigger particularly in diameter.
Hamlin is a specialised reed manufacturer. Ultralow power relays are often
made with reeds so you can often get reeds that way from surplus stores.
You could also use a NO reed switch combined with a low threshold Supertex
Vfet with 10M pull down resistor on the gate.
The reeds are fairly fragile, especially while soldering it is easy to crack
the glass seal. Shock mount with five minute epoxy or hotglue.
Regards,
Tim Hughes
>>Hi100@xxxxxxx<<
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