I'm trying to do a project where I use a servo motor to flick up and down (maybe 30 degree each way) very rapidly. When I got the servo motor from the genuino set, it looks like this
I'm trying to follow this youtube video and it mentioned also not to use the computer as your power source, is it really a big deal? As I don't have an external battery holder.
cheeteck15:
is it really a big deal?
Why do you think you were being warned if it wasn't? Or you just need one more person on an internet forum to tell you in order to convince you?
Yes, it will destroy your Arduino. Only the control signal should come from Arduino. The servo needs it's own power not coming through Arduino and definitely not coming from your computer.
Sorry I have no background in this, Im just learning. Usually for the previous projects I have been using the genuino as the power source, so why is this so different?
cheeteck15:
Usually for the previous projects I have been using the genuino as the power source, so why is this so different?
What were you powering? How much current did it draw? Motors need a lot of current. Try to pull too much through poor little Arduino and he'll start smoking.
So in genuino there are like 15 projects, the first one is simply turning on an led bulb with a switch, third one is a temperature sensor that changes the led bulb when the temperature changes etc.
also, is there something wrong with the wiring as shown in the picture?
cheeteck15:
So in genuino there are like 15 projects, the first one is simply turning on an led bulb with a switch, third one is a temperature sensor that changes the led bulb when the temperature changes etc.
LEDs take a LOT less current than a motor.
cheeteck15:
also, is there something wrong with the wiring as shown in the picture?
You didn't show anything but the connector that came on the servo. Are you worried that the factory put it on wrong? Even if they did, that's just one end. So nobody knows how you plan to hook it up.
according to the guidebook that comes with the genuino set, they are using the arduino set as the battery so i was just trying to follow when i came across the youtube video saying that it might blow the usb. yeah, thats what i meant, im trying to follow the guidebook but then the wiring seems abit off, thats why i was wondering did the factory connect it wrongly
cheeteck15:
but then the wiring seems abit off
In what way? Come on man, you gotta communicate here.
The wiring doesn't look like standard servo wiring though it's difficult to tell from those pictures. But normally the + red wire is the centre one of the three.
But maybe the servos that come with Genuino kits are wired that way deliberately for some reason. I don't know I've never seen one of those kits. What do the instructions say about what connects where?
BTW those cheap micro servos won't actually move "very rapidly". Unless of course your idea of very rapidly is a lot slower than my idea of it.
Steve
Delta_G:
In what way? Come on man, you gotta communicate here.
ok coming out from the server motor, its white, red, black, but when it connects to the white colour thing in the picture, it is black, white,red. like towards the end in the picture, it can be seen that the white and red overlap
Ok. But whether that works or not depends on how you wire up the connector that connects to it.
cheeteck15:
I’m trying to follow this youtube video and it mentioned also not to use the computer as your power source, is it really a big deal? As I don’t have an external battery holder.
The question should be something like ‘why should we not use the computer as the power source?’ … or ‘what part of the computer are they talking about?’… or ‘what could happen if I did that?’
The question should not be ‘is it really a big deal?’ - since that demonstrates … you get the idea.
The reason is likely due to that particular power source not being able to supply the required amount of power or current to your device and/or switching effects may cause operational/hardware issues with the computer system and your device.
Generally the red wire goes to the +5 voltage, the black one to ground, and the white wire connects to the pin on the Arduino. As shown in the tutorials, you can hook up a small servo directly to an Arduino, and it'll work. The problem comes in when you are using the motor to move something. If the thing you are trying to move resists being moved at all, the servo motor will work harder and harder until it moves. The little motors can draw as much as 1 amp while trying to move a heavy load. And your Arduino can only supply a fraction of that.
Something's got to give. Since you probably didn't put a fuse in the line, it will likely be a part on the Arduino power system.
It's best to give the servo it's own power supply, just be sure the motor and the Arduino share the same ground.
Go into the Introductory Tutorial section.
There are some guides to powering Arduimo Projects.
e.g. http://forum.arduino.cc/index.php?topic=498224.0
Although I am not experienced in power projects, I got the habit to power peripherals directly from the power supply, not from the Board.
I use a regulated cheap micro supply module (3 USD) from 3.7V LiIon -or 3.2VNiMh batteries to 5V to the sensors, screens. At the end, my objective is to obtain devices which are not linked to the PC = much more handy, much more fun :-).
I carefully check the common ground :-).
+++
No experience in motors, but I know they draw a lot of current and more important, I found difficult to find out from the scarce technical specification of some items how much current they draw.
Also, the USB of my computer is very low power - I suspect most of PC have low power USB - I cant even charge my phone in a reasonable time. I did not measure but from the very long charging time of my phone comparing to the same charging time using wall socket adapter, my guess is not enough to safely power a motor anyway.
Odds of newbie being new will always dwarf the odds of a manufacturing error.
But you wouldn't know it round here lol
Who knows, the kit may simply make use of an icsp header that has an arrangement of 5v-I/O-gnd on male header pins. It'd be a quick and dirty way to give the learning user the instant gratification of a twitching servo.
All companies build their devices to a Global standard!
I do believe ther are aliens among us as the global standards seem to be many.
USB 1 was around 500mA.
USB 2 around 1000mA.
So not a lot to play with and dont forget that the Arduino has a polly fuse that will cut out on excess current (see Arduino Specks for more info)
What the servo draws depends of the servo (no model given)
Daz.
According to USB Specificcation - revision 2 :
that can be found here:
http://sdpha2.ucsd.edu/Lab_Equip_Manuals/usb_20.pdf
"4.3.1 Power Distribution
Each USB segment provides a limited amount of power over the cable. The host supplies power for use by
USB devices that are directly connected. In addition, any USB device may have its own power supply.
USB devices that rely totally on power from the cable are called bus-powered devices. In contrast, those
that have an alternate source of power are called self-powered devices. A hub also supplies power for its
connected USB devices."
Chapter 7 details the electrical part.
The rule of thumb looks to be a minimum of 750 mA (5 units x 150 mA - 750 mA) must be available for all USB 2.0 standard output. But this is only a part of the story.Some hobby users report a 900 mA by using "Battery Doctor".
Digging deeper into the problem, I found that some phone manufacturers limits the maximum charging current to some 100-150 mA in PC case. Whether this is true or not, I do not know. But it is in line with my findings that (all) my phones charges from USB PC in far longer time than in the case of wall socket adapter.
Another point that I found interesting is that there is very little info about total available current to all USB ports alltogether in a PC. I bet it is somewhere more info, but it takes to long for me and it is much more complicated than assumed at a first sight.
In my case, there are 8 ports, out of them I use 4-5 at a time, 1-3 incidentally and 3 of them are available for my desk work - including powering the Arduino Board while coding and prototyping.
However, maximum current rate is, well - maximum.
So the problem is rather: what is the current value that is available from a regular PC USB2.0 under real life circumstances, and for a long time?
+++
Now, for the motor side of the story, the relation between mechanical power, nominal voltage, current and efficiency on-spot and long time is something to study and - in my view- to check.
I found something more intuitive here:
https://simplemotor.com/calculations/
What I would do - and I will do when the time to my motors will come - is to connect a laboratory power supply to the motor and measure the current by drawing a graphic of current/time (at various voltage) - to account for the coils higher temperature - I suppose it will rise, but I shall see.
Then there is the point of starting the motor. I do not know if I can measure something at that moment by a digital multimeter. I am not experienced enough to use an oscilloscope in this purpose, but I will give it a try.
+++
Maybe these rows are not directly related to the topic, but I hope it helps, at least for the part of rising questions - that I admire in every human and I think it must be encouraged.
De omnibus dubitandum 
lastchancename:
Go into the Introductory Tutorial section.
There are some guides to powering Arduimo Projects.
Except the tutorials do show this schematic ...
thanks all for the reply, i will try to get an external power source. also, i do believe the servo motor is connected wrongly as i went to google the model sm-2309s and it appears to be wired differently than mine
