I think it is a bit risky to use magnet to control the on/off, especially
you put a magnet under the camera for a long time. The steel inside the
camera could be magnetized and cause functional problem.
C.H.Ling
----- Original Message -----
From: <HI100@xxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Cc: <chipstrat@xxxxxxxxx>
Sent: Saturday, March 10, 2001 6:11 AM
Subject: Re: [OM] Older Battery Eating OM 4's? Serial Nos.
> 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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