Automatic watering system

Hello!

I'm working on a quite popular project the automatic watering system for plants. Basically I'm using this http://www.instructables.com/id/Arduino-Automatic-Watering-System-For-Plants/#step0 tutorial from the Instructables.

The parts I use are almost the same as listed on the tutorial, but I'm using official Arduino board because I want to support the Arduino project by using the official board. The components I use for this project are listed below:

My problem is hardware related, it is that I'm not sure how to power the driver circuit and the pump. I have experience from projects which require smaller voltage such as optical links, temperature, humidity and other sensors, but I really don't have enough experience from projects which use higher voltages and currents so I'm asking some help from you guys.

I understood from the tutorial that the driver circuit is powered from one of the pins from Arduino. Can it really be so because I'm thinking that the driver circuit will require higher current to operate than the 50mA which is possible to take from the Arduino's pins. Or is another power 9V power supply required to power the driver circuit and the board. Thanks for help.

  • Robotik1

If , as it seems , that you have no electronics experience, it might be a good idea to look at some tutorials or schematics of similar setups. Obviously the motor isn't going to be powered by the arduino +5V onboard regulator so you must have misinterpreted something you read that referred to the motor being "driven" and thought that meant "powered" , which it doesn't. "Driven" is a reference to the control signals that "drive" the motor in the sense that the PWM signal determines the motor speed by varying the duty cycle of the signal connected to the ENable pin of the L298 chip. The photo clearly shows three pins for the power connection; a GND, Vcc (that's Motor Power to you) and +5V (that's L298 logic power to you). Read the L298 datasheet and you see the chip requires two different voltages : +5V for the logic and whatever voltage you are using to drive the motor. It also requires Direction pin inputs. I suggest you do not apply power to anything until you thoroughly understand what you are doing. One wrong move and your chip (and maybe the arduino) will be toast.

Thank you for your reply.

Yes I clearly misread the tutorial when it comes to powering the driver chip. Just to repeat this once again the logic power comes from Arduino's 5V pin and an external power supply with 3-9V output voltage is required to be connected to the driver chip's VCC pin to provide the motor power.

Is it good to use an AC/DC transformer with the right output voltage? In this case for example 6V 1A or 9V 1A or is that enough power for the pump.

What happens to the motor power supply if a malfunction in the pump occurs and it begins to take more current, is there a possible risk for electric shock from transformer then. Would it be safer to use a large 9V battery to power the pump? The downside of course would be that the battery needs to be recharged from time to time and it would provide power only for short periods of time.

I will be posting my wiring diagram here later before I continue my project just to be sure it is right.

This mini pump really sucks!

(from vendor webpage-reverse psychology marketing I guess)

There is a brand new special high tech device you might consider using : it's called a FUSE. http://www.radioshack.com/product/index.jsp?productId=2102786 If the ac/dc adaptor is plugged into ac and the output is dc , with an inline fuse (we still don't know the pump current rating so you'll have to measure it to choose the fuse value=> (operating current +30%).

raschemmel:

This mini pump really sucks!

(from vendor webpage-reverse psychology marketing I guess)

There is a brand new special high tech device you might consider using : it's called a FUSE. http://www.radioshack.com/product/index.jsp?productId=2102786 If the ac/dc adaptor is plugged into ac and the output is dc , with an inline fuse (we still don't know the pump current rating so you'll have to measure it to choose the fuse value=> (operating current +30%).

Another possible solution also is to ask what the current rating for the pump is from vendor because Radioshack doesn't ship orders to EU.