How many 9g servos can an USB handle

Community General Discussions
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1

Hi!
 
I need some confirmation to be sure - USB 2.0 can supply 500mA, and typical small 9g servos draw like 150mA, right? That means it's safe to have an arduino powering 3x 9g servos, running off an USB port..?
Also, how important is it to have an electrolytic capacitor in the start of power supply chain, to store current? At least in this particular case - how much will it help protect the USB port? Or if all motors are stalled, capacitor will run out of stored power, and the USB port can still be damaged?

2

A servo can draw a lot more with a load.

I think you may blow your USB port.  I would go with a 7.2v Lipo battery and a UBEC.  Both can be had off eBay for cheap.

3

I agree you probably shouldn’t try to drive more than maybe a

single servo from your USB port. However, I am agreeing for a different couple of reasons. A) Your arduino will probably draw more than 50mA :slight_smile: and B) unless you are driving the servos from the USB port before the power gets to the arduino, you will actually be trying to drive the servos from the voltage regulator that is on the arduino board.

4

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Thanks for the answers.

Will try to experiment around a bit, not too worried about burning the port (if this does happen, i will post to warn others reading :D).

I know how to test how much current does the motor / arduino draw, but there is no easy way to test how much can the port supply, right? Since you have mouse / webcam / whatever drawing power there as well, it’s not that easy to calculate either.

Also, in Windows control panel Device manager, there are some numbers on how much current your usb ports are giving out. If the motherboard is made by a decent company, these numbers are quite reliable, yes?

5

My experience with the

My experience with the insect bot mini and other setups told me that two servos are too much. There is still a microcontroller, a sensor and maybe a couple of LEDs to power, so your USB port will not provide enough for that.

 

6

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Okay, thanks guys :slight_smile:

7

@anchux, were you able to power the servo off just the UBS power?

I am wanting to build my own bait dropper for my DJI Mavic air and was hoping to run it all off the USB Power:

1 x Photo Resistor
1 x 10K resistor 1/4W
1 x Micro 9g servo