I’ve noticed that those self-flushing public toilets always seem to have a small red plastic window near the valve. I assume this is an infra-red motion sensor. But I wonder where the power comes for this and for the actuator that initiates the flush when you move away. My guess is that there is a small battery involved but I wouldn’t expect a small battery to last very long. If this did use a battery I would expect to see a small door that would probably require a key to open but I don’t recall seeing one. I can’t image that you’d need to dismantle the whole valve assembly to replace a battery. I suppose it might be possible to run a wire to supply electricity for this through the water line but the installation could be very difficult.
Is there a Doper out there who actually works with these things that could answer my question?
it’s an infra red proximity sensor - in all the units I’ve seen it was mounted in the wall because the cistern was hidden or built into the wall (presumably to prevent vandalism).
Don’t lean forward to tie your shoelace when sitting on one of these toilets.
Sorry, I don’t know where the power comes from; I had always assumed it would be mains.
I always assumed the power came from water running through the pipes spinning a baby generator (for units mounted on the pipe). That generator could be used to charge a capacitor for continuous operation. IR emitters are pretty low power so they don’t need much juice to keep going (consider how long the batteries in your remote at home last even with constant use).
I’ve seen some that were built into the wall which I assume are just powered by the buildings electrical system.
I was especially thinking of urinals where the water pipe sticks out of the wall to which the flush valve is directly attached and then the urinal is right underneath. In the non-automatic version there is a handle you pull to flush. But in the automatic version there is no handle and the valve unit appears to be self-contained. And I see no wires going to it. I have also seen a similar valve on a toilet as well as a toilet that has the sensor in the wall. I assumed when there is a sensor in the wall it would get its power from the mains.
Actually, that little window hides an X10 camera. There’s a midget hiding in the janitor’s closet, watching your every move. When it’s time to flush, he does it by remote control.
Little-know fact (apparently) about those self-flushing commodes:
You can manually flush them. There’s a button on the top, side, or on the wall above the commode. Press that sucker and that way you don’t leave your “work of art” for someone else to “admire.”
Hey, I worked on that Sloan sensor project. Little known fact: it has a handheld IR remote control, so you can adjust all the controls without opening the case. We were discussing the battery version when I left for another job. Water-powered generators would have been cool, but the total project cost is way, way lower using batteries instead.
We got our 15 minutes of fame in BEAVIS AND BUTTHEAD DO AMERICA, when Butthead is walking down the row of urinals, waving his hand in front of each sensor, saying something like “This is the coolest thing I have ever seen in my entire life.”
