The first tests for the timing of my arduino powered ebb and flow system did not really go as well as planned unfortunatly:

  • i am having HUGE power fluctuations in the pump, so each and every time i setup a precise timing, i get different fill speeds, wich pretty much defeats the whole “precise timing for a precise filling”.
    • in a lot of cases the motor starts of veeery slowly, and the speedup rate to an acceptable level always varies
    • sometimes about halfway through the timing interval (set at 180 seconds for now), i will get a sudden decrease in power : my guess is this is tied to the tip120 transistor, and the lack of sufficient differencial :  i managed to reduce this problem somewhat by exchanging the 1k transistor that goes to the base from the Arduino digital pin with a lower rated resistor
  • these problems are unlikely to come directly from the pump as i did not have such fluctuation when running it directly on the power supply
  • i am also aware that using a cheap 8$ pump which eats up 2.2A at 5v (twice what was indicated on the seller’s site) is also begging for problems
  • I am not really good at electronics, but from what i gathered, i might need to add a few capacitors to smooth out the current and reduce the spikes…. more info here
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5 thoughts on “HydroDuino Pump Control Problems

  • April 16, 2009 at 09:32

    I’m follow your experiment.
    There are any news?
    Arduino can control your pump?

    • April 17, 2009 at 09:17

      Hello Davide !
      Thanks for your interest in the project: yes it does work quite well with the Arduino!

      I did have to make a few changes though :
      -use a few simple water detectors to turn of the pump in case of overflow
      -i used a mosfet instead of a tip 120 transistor, the control of the pump is much more reactive
      -i switched back to using 12v for the pump, 5v just was not enough

      The project is on temporary hold for a little while though:
      -the mosfet still gets hot very fast, so i need to get some heatsinks
      -i am also looking for better quality , lower amperage pumps

      As soon as i have more new i will post an update, with pictures, layout and code.

  • August 4, 2009 at 05:51


    Nice project, what type of pump did you use? Where did you get it from?

    • August 18, 2009 at 14:34

      Hello Amir!
      It is a very simple window washer pump (from cars for example), you can find these types of pumps for about 10-15 dollars on ebay:)

  • November 3, 2009 at 07:09

    I’m using pretty much the same exact pump! From a Ford? The way I have this working is from a 12V adapter rated for 1A. It seems to work fine and lifts enough (about 5 feet) for my purposes.

    I run the 12V line directly to the pump and turn it on with a TIP120 transistor just like you, the Arduino controls the transistor.
    For the 5v supply of the Arduino, I use a 7805 voltage regular to drop the 12V line to 5V for the ATMega168 chip. I have it running off the internal 8MHz oscillator without a crystal so it could all work without the actual Arduinio board and be standalone.

    I was also having problems with the pump when I hooked up the 5V regulator. This was solved by putting two 0.5uF capacitors on the input and output of the 7805 to ground. These pumps are made to be run at 12V. I tried it doing at 5V for less noise which was nice, but it just wouldn’t lift the necessary amount.


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