Overview
I needed a mechanism for controlling an electrical device (pump) on a water level, it was necessary that the pump is switched on when the level was reached, and works for a short time (20 seconds) and then it stops and the cycle, start again.I found nothing in shops that will make it at a reasonable price, so I had to make it myself. If this occurs to you, here's how I solved it.
The principle is simple, it detects the liquid level, the detection commands a timer that turns on the pump for a given time.
Water level detection
Timer
Power command
It's so the relay who will switch on and off the pump during the 20 seconds, each time the high level will be reached.
Power supply
I recycle a mobile phone power suply that you, probably like me, have several in a box in your attic. About mobile phone, are you like me bother by the stupidity of mobile phone factory engineers who seems to be proud to make fully incompatible power supply, even in different models of the same constructor...
Imagine that's only for delivering a small DC power and it's impossible to have a universal socket and tension.I suppose it's an economic process too smart for me... I hope so.
Final schema
Conclusion
You have probably noticed that I have recycled the most parts of the system, that make a cheap whole, about $5, but it work fine since September 2009.
