Decoupling Capacitor/s for QIK2s9v1 with single Power Supply

I would like to use a single power supply to run the following:

  • Arduino Micro
  • Qik 2s9v1
  • 4 QTR-1A sensors
  • 2 DC motors (specs: input 4.5-15.0v / no load @ 0.15a / Maximum efficiency @ 0.84a)
  • 1 Infrared receiver.

The Power supply I have is providing 7,5v at 2250ma which will be connected to the Arduinos’ VCC input and the Qiks’ Motor power.
The Arduino will also be used to provide 5v to each of the sensors, IR receiver and Qiks’ logic power.
To avoid the risk of voltage droop (malfunctioning the Arduino), could you please advise me if I should use one or more decoupling capacitors and where to put them?
I do not fully understand the difference between the capacitors so could you please also tell me which type would be best and its specs (e.g. xxxx uf, ceramic, radial etc…).
I tried looking on one website but they had 25 different sub types!.

Thanks in advance!


It’s mostly a case of adding capacitance as necessary, and it’s very dependent on your particular system. It’s possible you’ll be fine without any additional capacitors; do you have access to an oscilloscope that you can use to look at your supply voltage while your system is running? I don’t think you should worry about it until you actually have indications of a problem (e.g. the Arduino randomly resets).

- Ben

Thanks for the info, I will try with the twin motor setup and see how it goes.
Regarding the oscilloscope, I don’t have yet one but was considering getting a basic one for similar problems.
Could you please recommend a basic oscilloscope to check this type of thing?
I was looking at a DSO nano V2 or V3 but not sure if it would do the job.

Unfortunately, I don’t really have anything basic to recommend you. The DSO Nano could be useful, but it might not be fast enough to catch quick transients. I haven’t used one myself, but I know of someone who has it and is happy with it (though I think he mainly uses it to debug logic connections).

- Ben