So, i'm trying to make a hand with five SG90 servomotors and i want to control it by using the HC-05 bluetooth module with a phone app. I've been reading a lot and i'm not sure how i should be powering all of these. Could i just use a 9 volts 2 amps power supply and connect it to all of them? Any help is very much appreciated.
They are rated for 4.8V to 6V. Why not use a 5V supply
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Is a 5v 2a supply enough for all the servos and the bluetooth module? Could it power the arduino board as well?
Which one?
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arduino UNO
2A should be OK.
Personally, I would go a little higher, maybe 3,4,or 5A, just to cover any unexpected problems
Great, thank you really much!
The stall current of the SG-90 is around 0.7 A (and they draw that every time they start moving), so your power supply should be rated for 4.8-6V and 5 x 0.7 = 3.5 A, minimum.
You might be able to get away with less current, but if the servos start twitching, that is almost always a power supply problem.
This website says 360mA and that was with real testing.
Other people report measuring up to 0.8 A. There are many manufacturers producing servos called "SG-90".
It is silly and bad practice to underestimate power requirements of electromechanical components, and to recommend doing so to beginners.
The stall current is when they are stalled.
Start current is when they are starting.
Two different current ratings.
You are misinformed. The stall condition is defined as "shaft not rotating", which means no counter-EMF is being generated by the motor.
All brushed DC motors briefly draw the full stall current, limited only by the winding resistance, every time they start moving.
It is quite simple to verify that, experimentally, and if you feel like brushing up on DC motor theory, here is a good reference.
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Learn something new every day
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For permanent connections you need screw terminals. I've used that type of shield and its harder than it looks to make good connections.
I build Power Distribution Boards and use them to power everything.
That and connector shrouds for the duponts:
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