[MakeLV] Replacement magnetic reed switch for bike computer?

[Rob Roschewsk]

Can't remember ... does "The Shack" still sell security system parts
.... pick up a door/window sensor and strip the reed switch from that.

On 3/23/12, Randy Kramer <rhkramer at gmail.com> wrote:
> Has anyone here ever picked out a magnetic reed switch to use as a
> replacement
> for a bike computer (i.e., electronic bike speedometer / odometer ...)?
>
> We have two bike computers that are non-working because the reed switches
> have
> died.  (Both due to impact, they no longer switch, they're stuck in one
> position.  I've tried tapping them fairly hard to get them to operate again,
> but no luck.)
>
> I'd like to buy an off the shelf reed switch and solder it in place of the
> original.
>
> If anybody has done that, do you have a reed switch you'd recommend?
>
> If not, I did a little bit of looking.  The reed switch in one of the speed
> sensors is about 1/2" long.  I found a reed switch that is 1/10" (diameter)
> by about 1/2", so it should physically fit.
>
> Here is the switch I found:
>
> SWITCH,MAG REED,SPST-NO 0.5A at 100VDC. JAMECO VALUEPRO MKA-14103-1015-R
>
> http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_171872_-1
>
> and a link to the data sheet:
>
> http://www.jameco.com/Jameco/Products/ProdDS/171872.pdf
>
> I can't copy and paste from that .pdf, so I'll mention a few things:
>
> The battery operating the computer is (depending on the computer) either a
> 3.2
> or 1.6 volt button cell. (2032 or 2016).  Thus, I'm sure the voltage at the
> reed switch is no higher than that (it could be, I haven't measured it, but
> I
> doubt it is any higher).  So, I need contacts with low contact resistance.
>
> I don't need high current capability.
>
> I do want good resistance to mechanical shock.  This one is rated to
> withstand
> 1 msec. shocks of up to 150 g, and sinusoidal vibration of 1 to 2000 Hz. at
> 20 g.  Sounds likely to be tough enough.
>
> Any comments, other suggestions?
>
> Thanks!
> Randy Kramer
>
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