If you can handle a $20 part, Analog Devices makes real accelerometers that
are very easy to interface to a PIC CCP module or an A/D port.

I have two samples of an ADXL202EX (I think the x means pre-production) on
my desk that I'm just trying to find the time to play with.  These are about
1/4" square, and are a 2-axis +-2G accelerometer with about .1% resolution.
They also come in a 14-pin DIP, which may be cheaper and easier to get.

You could get real fancy, integrate for the velocity and adjust the timing
to keep the size of the  letters constant.

> -----Original Message-----
> From: M. Adam Davis [mailto:adavis@UBASICS.COM]
> Sent: Friday, September 01, 2000 9:06 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE] Simple direction sensing
>
>
> A more complicated approach, but still inexpensive, is to
> hinge the handle from
> the display.  Use a very strong spring so that swinging it in
> either direction
> bends the hinge a very small amount.  You could then use
> cheap contacts, or even
> a pot, to tell which way the device is being swung by the
> bend in the hinge.
> Use a pot, and you can tell the acceleration.
>
> One item it note, though, most of these methods tend to
> equalize, after the firt
> swing or so you won't be able to tel direction by
> acceleration forces in either
> direction.
>
> -Adam
>
> Brian Jones wrote:
> >
> > 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?
> >
> > Thanks
> >
> > Brian
> > Brian E Jones
> > Centre for Java Technology
> > IBM HURSLEY
> >
> > --
> > http://www.piclist.com hint: The PICList is archived three different
> > ways.  See http://www.piclist.com/#archives for details.
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.