[plug] Call me crazy...

[bob]

On Wed, 29 Oct 2003 10:37 am, James Devenish wrote:
> In message <BBC5435B.2451%ahewitt at globaldial.com>
>
> on Wed, Oct 29, 2003 at 10:13:47AM +0800, Adam Hewitt wrote:
> > But does anyone with any significant electronics knowledge know if it
> > would be possible to somehow connect a kettle to a serial port on a PC
>
> The PC might have to be somewhat close to the kettle, or your wires will
> be inoperably long.

You should be able to get at least 20m at 19.2k. Further for lower speed 
(and what I'm going to describe is waaaay lower :)

> > so that you could boil the kettle from your desktop and get some type
> > of reading to tell you when its boiled??
>
> Fine in principle, but it will depend on the model of kettle. Other than
> whether it is moulded/welded in such a way that you would have to wreck
> it to get at its insides, also consider that different rocker switch and
> thermostat mechanisms might be easier to mingle with than others.
> People have connected small devices such as coffee machines to the
> Internet, so the concept is proven.

NB! this is "kill you dead" mains power we're playing with here. Do not do 
this if you are not entirely sure you know what you are doing.

I think these days we can assume an auto cutoff type of kettle (whichever 
way its handled, not important to the design). I think the simplest 
solution would be to monitor the current use and the simplest way I've seen 
to do that is to run the power through a stepdown transformer A side while 
driving an optocoupler from the output of the B side. The opto should then 
deliver a square(ish) wave at 50Hz. Clock that in to your port and voila - 
or as the French would say - Beaudy 


-- 
If bankers can count, how come they have eight windows and only four 
tellers?

_______________________________________________
plug mailing list
plug at plug.linux.org.au
http://mail.plug.linux.org.au/cgi-bin/mailman/listinfo/plug