In my RC servo motor datasheet the shall current is 600 mA. My Arduino cannot supply that much of current so, I decided to use an DC adapter to supply the power and arduino to control the Servo. My question is – Can I connect a DC adapter of 5 volts and 1A to the servo. I have read some where that servo motor just take current (not voltage) what it needs even tough you supply more than enough. Is it right?
Electronic – RC Servo motor power supply
servo
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First, let me say that you didn't give enough information to say for certain what's causing the problem. Not a big deal, really, except that you have to understand that my answer may not be 100% correct.
The link to the Hobbico web site doesn't give much information about that servo. I "think" it says that it will pull 0.7 amps when running without a load. If this is the case, then you can assume that at startup or with a load (a.k.a. plate) it will consume more than 0.7 amps. This amount of current does not seem high to me, given the large size of the servo.
What we don't know is just how much more than 0.7 amps does the servo consume. A good guess is, "way more than 0.3 amps more". What this means is that you are likely drawing more current than what the 1 amp power supply can provide.
There are several things that could happen when the servo tries to consume more power than is available. Odds are that one or more of these things is happening:
- Power Supply (PS) output dips, causing a loss of torque in the servo. This will make the servo stick until pushed.
- PS output dips, causing the control electronics in the servo to reset.
- PS output dips, causing the Arduino board to lock up or reset.
- PS detects a fault and shuts off. It might turn back on immediately, or after a while, or not at all until it is unplugged and replugged.
- PS gets damaged.
The simple way to see if any of this is happening is to put an o-scope on the output of the power supply. While you have the o-scope out, you might as well look at other signals, like the signals going to the servo. You could also try a different, more powerful, power supply but that is less informative.
So in general when you have a noisy actuator and a sensitive you run them on separate supplies and try and keep the two electrically isolated. I use a circuit like this when I try and opto-isolate a transmitter and a receiver:
This will give you a non-inverted output of the input waveform, and will actually work with any voltage on the input and output side so long as you can still turn on the LED (i.e. the input voltage is high enough) and you are within the operating voltage of the output transistor.
Isolating the two supplies is actually good in a lot of ways. It means you don't have to worry about surges in current on the actuator supply causing issues on the microcontroller (fewer decoupling caps, etc), and it also means that if the actuator battery dies, the actuator won't try and run off the input signal from the microcontroller.
Hope that helps!
Best Answer
Yes, the motor will only take the current it requires (and that current will vary depending on load - perhaps more than 600 mA when starting, and much less when running with a very light load.)