Re: Automate the washing machine's signals???

["David Buckley" <db@xxxxxxx>]

--- In ukha_d@xxxxxxx, "Derek Erb" <erb@e...> wrote:
> The problem is this:  When the washing machine finishes it
> makes to most obnoxious, annoying and loud beeping sound.

If the beep is genuinely a beep (as in a tone) then you may be in
luck, though some assembly is required.

There is a type of chip known as a Phase Locked Loop, or PLL.  These
devices can be used for tone detection.  The PLL spends its
life "hunting" within a range of frequencies you program it for,
and
should a tone appear within this window, the PLL will "lock" onto
this frequency, and an output from the chip is activated.

So,....  all you need is a microphone (cheap and nasty will do, as
its only a squeak that you're looking for), a preamp, a PLL, and
then something to do with the output.

For post processing after the PLL, what you need is a PIC or
something (VIOM? Basic STAMP? anything like that) to count pulses,
so that you can detect a real series of beeps, not just a false
squeak of about the right frequency caused by something mechanical,
for example.  It also does the interface to your relay that drives
that 6 inch bell placed upstairs....

Suitable PLL chips include the NE567, XR2211, or possibly 4046 if
you're feeling brave.  A single opamp should be enough for the mic
preamp, this is not a hifi application.

You'll also need access to a scope or something to measure the
frequency of the bleep.  Or record it into goldwave on a PC, and
measure the time between full cycles and do the math. Once you know
the frequency, the data sheet for your PLL will give you the formula
to calculate the frequency dependent bits.  Allow a bit of leeway in
the range!

I had a google search for something that could be modified to save
you a load of work, and the nearest was
http://www.farcircuits.net/control2.htm#10control
but thats just a
PCB, no data or schematic, but it looks exactly the right sort of
thing, a preamp followed by a PLL (well, three PLLs).  My guess is
that the circuit uses the three PLLs to light three LEDs for too
high, too low, and spot on.  Utilising this board should thus be
trivial; just populate one NE567 chip not three.

Do I get the award for the craziest suggestion?


> End_of_Wash() {
>   beep(5) times;
>   wait(12) seconds;
>   Call End_of_Wash();
> };

This is, of course, recursive, and if upstairs dont come down and
stop it, or the thing doesnt eventually get bored counting, the
processor will eventually run out of stack space and crash... :-)

David



UK Home Automation Meet 2004 - BOOK NOW!
http://www.ukha2004.com

http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx