Who knows what else they did then.  You could use a pickup made from a two wire hall effect sensor and maybe that requires shielding?  Doesn't make sense to me considering how dependable a reed switch is - a billion operations are quoted by manufacturers if they are encapsulated with an inert gas.

I am guessing that given the difficulty generating a strong enough field using cheap magnets (we have all fiddled with a computer that seem hard to trip) maybe they get more sensitivity with a more complicated pickup.  Any complication that would require an electronic pickup could be alleviated by using a nice neodymium magnet with a properly specified reed switch.

Here is another idea.  There is a proliferation of wireless systems.  I never use them so I have no idea if they use reed switches or not.  But if they do not, and use instead a hall effect circuit, that could create an economic situation where reuse of the wireless pickup, but with wire makes sense - they piggy back the wired volume onto the greater wireless pickup use thereby getting a better purchase price for the components all around.  But the wires can become an antenna for stray electrical noise and coaxial is needed to keep the signal clean.  This would never be a problem with a read switch alone.  That is all rash speculation.

BTW, I get it about the eyes and close work.  I have extra strong reading glasses lying about everywhere at work and home.  I even stack two pairs when soldering surface mount components by hand.  Two pairs with 3.25 magnification will do the trick.

Mike







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Michael Ross
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Cycling in Central North Carolina
Schwinn Voyageur 11.8
Linear LWB, Greenspeed GTO, BikeE CT, AT