Another Option
After speaking with Andy about reliability of the data using sound, I decided that we need to determine another option to collect data. One option Andy suggested was to use a current clamp to determine how much juice is going through the power cable to the washer or dryer. This should vary depending on the cycle of the washing machine and potentially the time in the dryer (as the dryer heats up, it would use less energy).
Here’s a website that describes how to create a current clamp: http://www.siliconchip.com.au/cms/A_30669/article.html
Once that is created, it would be a simple circuit to measure the voltage that is created from the circuit.
March 10th, 2006 at 9:18 am
http://laundry.mit.edu/
March 10th, 2006 at 12:25 pm
Why not a small ruggedized device that can be placed with the laundry inside the machine that detects motion…when the motion stops, the wash/dry is done.
March 10th, 2006 at 4:22 pm
Another way to pick up the sound might be a contact mic. You could place it on the motor a surface that’s fairly isolated from the basin. These things get a bit powerful though, so you might need some sort of limiter circuit on it. Take a look at these sites:
http://www.muzikaktiv.com/contactmics.html
and
http://home.earthlink.net/~erinys/contactmic.html
I’ve built many basically using the second link and they are quite remarkable.
Hope this helps.
March 10th, 2006 at 8:13 pm
here is something I can up with a while back http://blog.stevienova.com/2004/09/22/laundry-machine-automatic-notification-system/
March 11th, 2006 at 8:28 am
Maybe a small resonant coil to pick up the electromagnetic inductance, tuned to 60Hz? This would eliminate possible mechanical points of failure, since it would only need to be in the near field of the motor to work. Guess it’s kind of along the lines of the current clamp idea…
March 11th, 2006 at 11:58 am
Another non invasive option would be to use a webcam to watch for the status lights or movement of the mechanical timer (depending on model).
August 22nd, 2007 at 9:05 am
I had need of this a few years back. You see in the UK most washer have no cycle finished buzzer, therefore I decided to build one for my mother, who at the time ran a successful B&B and needed to do several washing loads each day.
It just consisted of a vibration sensor linked to a single transistor capacitor bucket charge circuit. Every time the machine moved the capacitor was discharged. When the cycle was finished the circuit would reach full charge (after about 5 minutes) and trigger a LOUD buzzer.
This devices worked very well and because it was only wedged between the washer and the underside of the worktop it was an easy matter to move it between machines as needed.
In your case what would be ideal would be something similar with an RF link to a PC. Assuming an average of 55min/cycle and a calm inter-cycle period (filling, draining) of around 5 minutes. You should set the charge circuit to 7 minutes and upon use the computer would start at 60minutes until next wash.
August 22nd, 2007 at 2:11 pm
There are several possibilities.
Do they have a buzzer / alarm that goes off when they finish? If they do, this is the sound you could look for.
Does the washer have LED / Lamp indicators of some kind? A photo detector that sticks on might work.
A pedometer stuck on could work. The washer would vibrate a lot previous to the end of a cycle, and a dryer would stop abruptly.
Many modern dryers have a cool down phase. Something to detect a sudden temperature drop on the dryer exhaust would tell you of an impending cycle end.
Other design considerations : Do these units have a common plug for the washer / dryer pair? If you can get permission to open them up, you could attach directly to the control board. Doubtful, but it would simplify things greatly.
Great project by the way. In our dorm we had a dryer that the timer was busted and I forgot about my load all day long. My pacman ‘applique’ type shirt that had survived nearly a decade didn’t make the 10 hour dry.