Here at Instructables HQ on San Francisco's Pier 9, the men's restroom had a problem.
Particular pier peers persist as poor-precision pee-ers. The result of which is photographed above. (Emphasis added).
Solution: Positive-peer pressure for proper peeing posture. The Urinal Spash Danger Meter
A solar powered electric apparatus for displaying pee-stance quality* and correlated splash risk.
The concept is explained in this excellent video.
*Pee-stance quality is directly proportional to distance from urinal. Closer is always better.
Step 1: Aquire Parts - Begin Tuning
How does it work?
It is deceptively simple. It is just a solar panel and a analog meter. The more light that hits it, the more danger it indicates. The closer a person is to the meter, while properly lit, the less danger it indicates. Being solar, it requires no batteries or plugs.
This is a somewhat difficult process. I got lucky and had a bathroom with a strong directional light source directly above the users head. Because of this, a stark shadow is cast on the solar panel which causes the needle to drop. I do not know if there is a good reason to use a ammeter vs a voltmeter, as both increase as light increases. I was more confident in an ammeter as I was getting noisy results on voltage.
Note that if the difference is smaller than 20 microAmps, you will need to either get a bigger panel or change the lighting in your bathroom. I have not been able to find any analog meters that have precision less than 20 microAmps.
Once you have your parts on hand, hook the panel up to the meter. Red to + and Black to -. You should have immediate response to changing light levels. Find a place on the bathroom wall that works with your parts.
My Parts list:
Note that your parts may differ, as your restroom is non-identical to mine.
Step 2: Design the New Meter
The ?A label is not going to cut it if we want people to know what is going on. Time to make our own!
The finished files are attached, so these steps are only needed if you want to design your own.
Designing Gauge Face
In order to make this thing look official and sciencey I decided to use DIN, a nice german font. After a lot of thinking and math, it was determined that the scalar quantity being measured by this solar apparatus is ?Droplets/cubit? (microdroplets per square cubit). The meter reads in a exponential fashion, with an asymptote at infinity. Demarcating the danger zone requires testing your panel and your meter ahead of time. I got lucky and had a pretty even spread.
Trim and glue
The design can be cut out of regular printer paper and glue-sticked to the old face. Simply force the cover off the gauge and slide the sticky print behind the needle. Once set, reassemble the gauge.
Step 3: Design the Plastic Chassis
The meter needed to be mounted on something. A project box would have worked too, but I wanted something sleeker. There are thousands of ways to do this, and I'd love to see how others solve this problem in the comments.
I decided to use black acrylic plastic(Plexiglas) as it is easy to heat bend and easy to laser cut. Don't have a laser cutter? Don't fret. Simply print the stencil and drill the holes. There are two components and they can pretty much be mounted to anything.
Step 4: Cut, Bend, Populate Chassis
Step 5: Install, and wash your damn hands
Now that you have a fully tuned and assembled Splashometer, stick it to the wall with the 3M Dual-Lock (Velcro) and wash your damn hands.