Hi,
I want to power an Arduino and a RC Servo with one power supply. So I have a 9V 2A power supply and use this 9V direct into the VIN pin. The servo operates with 4.8-6V so I use a step down converter to transform the 9v into 5.5V.
I connected all as shown in the figure.
Do you see any problems? Any improvements?
It´s working, but I´m not sure if this is the best solution.
For testing purposes I connected the USB port of the Arduino to the PC and programmed the Arduino and the 9V power supply was NOT connected, so the servo could not move.
But the servo made a strange "noise".
Could the servo be damaged?
Can I connect the power supply to the socket, although the Arduino is connected via USB with the PC?
Can I connect the power supply to the socket, although the Arduino is connected via USB with the PC?
Yes the Arduino has a switch inside that detects that condition and turns off the USB power.
and the 9V power supply was NOT connected, so the servo could not move.
But the servo made a strange "noise".
Running stuff like that is asking for trouble, you are putting an Arduino logic output into an unpowered servo. That means you will get parasitic powering of the servo and probably overloading the Arduino’s output pin. It is not surprising you might hear some sound.
To improve the circuit add supply decoupling to the servo in the form of a large capacitor close to the servo.
At the moment all external modules are powered over the Arduino 5V Pin. I have a display, a buzzer, the buttons etc.
Now I want to replace the stupid buzzer with the minidf mp3 player module and a 3W speaker.
Would it be in general a better solution to power all modules from the external 5V?
No connection from 5V pin of the Arduino (only the buttons and poti) and draw another line from the 5V DC-DC stepdown converter to power not only the servo, but also the display, the speaker etc.?
And cut off an old usb connector and give the arduino the 5V from the converter into the usb port?
So, the hole system is operating with 5V.
Maybe I replace later the 9V power supply with the step down converter with a 5V power supply and power the system from that?
Do you understand what I mean, or should I make another schema?
I'd definitely not power anything else from the servo's supply, anything with a motor is very noisy and likely
to put spikes and dips onto its power rail. The Arduino's 5V pin provides regulated power and is clean.
If you need more power at 5V for sensors/modules etc, use an external 5V regulator, so as not to overload
the on-board 5V regulator. An external regulator can have a heatsink. If nothing is analog another DC-DC
converter would be suitable too, as its switching noise isn't an issue without analog sensors involved.
MarkT:
I'd definitely not power anything else from the servo's supply, anything with a motor is very noisy and likely
to put spikes and dips onto its power rail. The Arduino's 5V pin provides regulated power and is clean.
Ok! Currently I power the Arduino and the Servo from one power supply, but this is not a problem because I use the VIN Pin of the Arduino and there is a regulator , right?
(see the schema from my first post)
MarkT:
If you need more power at 5V for sensors/modules etc, use an external 5V regulator, so as not to overload
the on-board 5V regulator. An external regulator can have a heatsink. If nothing is analog another DC-DC
converter would be suitable too, as its switching noise isn't an issue without analog sensors involved.
I´m, only worried about the minidf player with the 3W speaker. I use this mp3 module and it´s connected like there.
The servo is only doing a short movements (with a long delay between each move) and the sound is only playing after the servo has moved for about 1-3 seconds.
So, this should be safe and last long?
This is part of a simple tea-machine I built and I don´t have fun to replace the burned Arduino every week
And cut off an old usb connector and give the arduino the 5V from the converter into the usb port?
I would go in at the USB end, you miss out on the USB protection circuit by going straight into the 5V.
Using two regulators from a single power source is much better than trying to run them off one regulator. You will not burn anything out, but you might get noise from the servo into the audio and at worse the electrical noise from the servo can cause problems like randomly resetting the Arduino. Good supply decoupling will help.
