-------------------
Now consider a urinal which flushes automatically. The tank valve is opened by some sort of trip switch. It flushes, the tank refills and when a given level is reached, the trip switch operates. In terms of control theory, it is a "relaxation oscillator" and there are electrical equivalents.
A bit like the old 555 timer circuit. Charge the cap (tank), when it reaches the trigger threshold (water lifts the float to open the flush valve), and away we go.....
Analogies like this can be fun for a bit (of course, there are limits). I taught a class on process controls to some non-engineers once. Explained a lot about proportional controls with the float valve example. Put the pivot point of the float arm on a vertical, threaded shaft, where a very-slow speed motor turned the shaft one direction or the other whenever the level wasn't at the desired. That was the integral control. A couple of the folks had a 'forehead slapping Doh!!! ' moment when they finally figured it out. :-)
daestrom
When the capacitor (tank) is discharged to 0 volts (no more water pressure/weight of water in the the tank), it allows the SCR (flapper valve) to close. I was also trying to come up with a way to illustrate inductance; maybe a siphon is more illustrative of something more complex.
sounds like your analogy is in the toilet.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required