Plug and Play Logic Gates
And Gates, only turn on the output when both the inputs are turned on.
So, it's very pretty, but what does it mean?
There are probably some complex ways to do this with tranisitors, if you know how mail me and I can put them up here but for most home uses this is the easiest and the best.
When the tank has water in it and the battery is full turn on the pump. So when have two inputs, a float switch and battery voltage detector. And we have an output, a pump , which we only want to turn on when both the inputs are on.
The that almost always has water, so we put the positive from the float to I1, the positive from the voltage detector on I2 and join the negatives together and attach them. Then we join the pumps negative and positive to the output connections.
So what the battery detector turns "on" the relay is powered and it closes the switch. If the float switch is on then that power is passed onto the pump powering it.