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Plug and Play Logic Gates

And 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?

  • Neg: You need a common negative so that runs through the box
  • I1: Runs through the box to Out if the relay is on
  • I2: Runs through the relay
  • Out: If there is power in I1 and I2 then there is power at Out
  • Relay: A relay is a coil of wire that generates a magnetic field if power is passed through it and a connection that is closed by that field. This is the limiting factor of the AND gate so you need to purchase a relay that will support the Amp you plan to put through the gate. Relays also consume small amounts of power when on, so it is a good idea to hook I2 to the less frequent of the input devices.
    relay close up

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.

Battery EmptyBattery Full
No Water in the tankPump OffPump Off
Water in the tankPump OffPUMP ON!!


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