I am new to this forum and even did some research before posting here, regardless, how stupid the question is, I could not find any appropriate answer.
I want to control two-three servos of this type:
The PWM Signal comes from an Arduino UNO, but now the problems start.
I want to get maximum torsional moment, so I need a voltage of 7.2 V.
I know that the Power in Joule or newton meter is Volt*Ampere, so 15 kg/cm = 7.2V * I if i divide by 7.2V i get (15kg/cm)/(7.2V)=I,
so I = 208.3 mA. But this is only true for this particular force, but the load is different while the servos are running. Even every servo has a different load, which is changing during runtime without any relation to the others.
I want to connect the servos to ONE additional electric source. But I don't know how to do this.
When I use a parallel circuit the voltage would be the same, but the ampere is added. The needed force is different, so the needed ampere is different too, how shoudl i balance this? Or does the servo adjust the needed Amperes? That means I just have to get a source with 7.2 V and the maximum possible Ampere load?
My brain is fried by thinking about this problem for the whole day now.
I would apprecciate some help really much.
And sorry for my bad English I hope the meaning is understandable.
You can power all your servos from one external (to Arduino) source. Each servo will draw the current it needs. Usually should have 1 Amp per servo, if they may run at the same time, so three servos- 7.2V at 3A for power supply. Connect the red wires form the servos to the external supply V+, all servo black (or brown) wires together and to V- of supply and Arduino ground, and the servo signal wires to PWM pins.
Ah thanks alot!! Even if 1A is too much for max load the servos will just don't draw this current, right? And why it is necessary to connect the black cable to V- of the supply and GND? Because of the PWM signal? Ah i think I got it: If I don't do that, there are more electrons flowing into Arduinos power supply, then the Arduino is emitting, and the extenal source is getting less electrons back, than emitting, this would end in a dead pwm signal or even a kind of bypass, or?
Again, thanks alot for your fast and good answer!!!
below is the basic way to power a servo in an arduino setup. Also note that the servo library is much easier to use than trying to generate the PWM in code.
1A per servo is on the "safe side" for hobby (model aircraft) servos. If you know the current requirements, of course, adjust accordingly. As long as the voltage to the servo is correct the current will be what the servo needs, no more. The grounds must be tied together so the PWM, or any signal from the Arduino, has a reference. And like Zoomcat says, The servo library that comes with the IDE makes controlling servos very easy.
That high-torque servo will probably need 2--3A or more - its 1.5 N-m - that's ten times
the usual torque for a small servo... If you need the torque measure the current under
load and ensure the supply is upto the job.
Note it will not be rated for continuous torque at that level, it will simply get too hot.
First: That drawing is really helpful, thanks and even for the hint to the servo library.
Second: So I have to do it like the drawing, thanks!
Third: Yes i need this torque, but only for a short time, Yes i will measure the current under (maximum ?) load, thanks.
What is the maximum torque for an extended period of time? Unfortunally there are no downloadable datasheets.
Even if 1A is too much for max load the servos will just don't draw this current, right? And why it is necessary to connect the black cable to V- of the supply and GND? Because of the PWM signal? Ah i think I got it: If I don't do that, there are more electrons flowing into Arduinos power supply, then the Arduino is emitting, and the extenal source is getting less electrons back, than emitting, this would end in a dead pwm signal or even a kind of bypass, or?