----- Original Message -----
From: "Brian Jones" <bejones@HURSLEY.IBM.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, September 01, 2000 10:30 AM
Subject: [EE] Simple direction sensing


> As a simple project for my local radio club I've designed a PIC
> Magic Wand that flashes 7 LEDs leaving a trailing message in the
> air. The flashing (ie message) is triggered by motion sensored by a
> mercury switch.
>
> Works fine if you wave right to left but moving left to right the
> message is mirror imaged (of course).
>
> Any ideas on a simple (and cheap) method of detecting whether
> motion is left-right or right-left so I can invert the message as
> appropriate. 2 mecury switches mounted in some way so that the
> leading edge triggered first seems the obvious solution but how to
> actually implement this?


Yes, here's a cheap and cheerful solution. Take a set of changeover contacts
from an old, large relay and:

Option A, attach a vane of card, plastic sheet etc to the common contact.

Option B attach a weight to the common contact.


Even if you don't have any it's a pretty safe bet that senior members of
your ham club will have some old PO-3000 type relays in the junk box at
home.

If not, I'm sure you can find some suitable springy material to make contact
strips from.






.

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