What kind of water pumps are you using? You may be set with normal I/O but that depends on what the input to the water pump is like. Chances are it has a power in and out, probably AC im guessing with your setup, which will not be drivable simply using the Galileo or any shields I'm aware of. What a lot of motor controller examples and other examples demonstrate is either through a relay or check the specifications of your pump's on/off switch. If it is 3-5 volts and will accept a current similar to that of the Arduino breakout pins, that may be your step in right there.
Thanks for the reply. I will be using a 12V DC centrifugal water pump rated at 1A. There is a two wire 'ground and live' wire setup which I may run through a step down transformer or possibly with transistors if this is possible to bring it down to a 5V output to one of the I/O pins.?
I plan on having a number of water level sensors to trigger the pump on and off, (int digitalRead (9 "Level Sensor",Input) digitalWrite (4 "Pump",output) etc... depending on certain parameters. If I can configure the pump to the arduino headers I think I should have no problem getting this to run.
Would you or anyone else see any stumbling blocks or issues with this approach?
Sorry about the late reply, Night shifts are getting the better of me!
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One way to do what you want is with a relay. They're pretty simple overall and work well with arduinos.
Here's some links which may get you started with schematics and hardware pieces:
Basically, the relay is controlled by a transistor, controlled by the arduino (galileo). The relay will control the constant power to the pump, and ground is always connected. Good luck, and post pics of your setup!
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Oh, and I would highly recommend testing your circuit with a resistor and LED in place of the water pump for testing, to make sure you get the proper on/off behavior with your circuit, using the same 12v source as your LED on/off. Once you get the right behavior, then hook up your pump (with water) so you don't blow the pump.
Thanks for all of the info, the links are quite informative. I think this gives me enough confidence to move forward with the project now without frying my board.
I will have to go ahead and purchase a few more parts before I can get it underway, but I will keep the progress posted with pics along the way. I'm sure I may have a few more questions from now until it is complete.
Relays create a back-EMF when they de-energise which can sometimes fry I/O. Power MOSFETS are much more robust and will give you no trouble for this kind of application.
My recommendation would be the following:
1. Connect your I/O pin to the gate of an N-channel MOSFET. Include a pull-up resistor (i.e. to Vcc, normally 4.7Kohm is well suited).
2. Pick up a power relay that is capable of running at least 12V @ 1A (i.e. virtually any relay you will pick up off-the-shelf).
3. Connect one end of the relay coil to ground and the other end to the drain leg of the MOSFET. If your relay coil is polar, take care to observe polarity.
4. Connect the source leg of the MOSFET to Vcc.
5. Connect a diode and nominally sized resistor (e.g. 1Kohm) in series across the coils (shunted) with the diode oriented for current flow from ground to Vcc; this will preferentially dissipate any back-EMF through the resistor.
6. To energise your relay, simply pull your I/O pin low. This will energise the MOSFET channel and allow current to flow from the source to the drain (and then to ground via your relay coil).
In this configuration, you have a robust actuated switch with your maximum switching capacity governed only by the capacity of the relay.
Hope this helps!