Back in 2009, I used to own a laundromat. It was a self-service unattended laundromat that was still coin-op, no card system. I wanted to know how much traffic my laundromat was getting, to see busy times of day and get some metrics without having to be there. Thus spawned a little invention of mine, the laundromat watcher.
How it worked
The first version of the laundromat watcher was based on the Arduino MEGA, it was hard-wired into each machine in the laundromat directly. I would open the machine, use a voltmeter to determine which circuits had power when the machine was running, and then tap into them with a simple neon light bulb. These bulbs can operate on almost any voltage and power which made them ideal for this purpose. Then I had a light sensor to see when the device was on. For machines that already had an on light I would just wire the sensor next to the existing bulb. I created a bunch of these sensors and wired them in. After writing a bunch of code, it worked!
What it could do
I was thinking what advantages I could add for the end-user, and that would be notifications that your laundry is finished so you wouldn’t have to wait around for it. So I added the ability to send texts and to post to twitter as well. This is what it looked like:
Tried to sell device
I created a website (matwatcher.com and laundromatwatcher.com) to see if there was any interest in buying a commercial product. I spoke with a few other laundromat owners, who liked the idea of getting new functionality and metrics without having to replace expensive commercial washers/dryers, but did not find enough interest, and the requirement to wire it into every machine killed the idea.
Another problem with the product is that new machines have this functionality built-in, so it is an ever-decreasing size of potential buyers, not really a sustainable business model!
These days, wireless embedded devies are much cheaper than ever before, so it should be possible to tap into the machine and have a wireless sensor for a lot less, and just use something like a Raspberry Pi or even a cloud service to eliminate as much hardware as possible. It might even be possible to use something like the Amazon “Tide buttons” to trigger the counters. As long as there is wifi you could monitor the entire laundromat quite easily. If anyone ever has any interest in making such a system I would love to be a part of the project. If you are local to Boston MA check out the next Arduino Meetup (I run that group) and we can discuss! Or reach out to me via RDAIT.