The servo raises a robotic arm. It attempts to raise it for a second and then it drops it right back down and twitches back and forth 5 degrees.
The servo is new and rated at 7.4V and can take up to 9A.
However my adjustable voltage power supply is only capable of 3A and is rated at 190W.
As the motor twitches back and forth the voltage drops significantly and fluctuates a lot anywhere from 3-6 volts, with amps also fluctuating like crazy around just 1-2A, not even going to 3.
Is insufficient current my problem?
The servos are digital so would the twitching be some sort of safety mechanism?
Most likely. Is the ardino powered from the same power supply? If so, the low voltage is probably causing the arduino to crash and reset. You can use the serial monitor to check for this. Also, do you have the servo grounds and arduino grounds connected together?
The Arduino is powered from my USB port. The grounds are connected together.
Here is a picture of my power supply. Perhaps I over estimated the current it could deliver even though it says 0-3A (190W/7.4V = 25A which is not under 3A )
A servo power supply needs to be able to supply the stall current, which that power supply cannot do.
According to the picture, the power supply output max appears to be 30 V and 3 A (90 watts maximum), so the "190W" rating might be the maximum power draw from the wall -- less than 50% efficient.
You try to pull 9A from a 3A supply and wonder if there might be insufficient current. Definitely -
the servo will be peaking 9A whenever it tries to move/accelerate or hits the endstop, causing the
supply to drop out completely and try and recover again, and again, and again. Suggest finding
a good battery pack capable of 9A peak without problems - the current to a servo is very bursty,
you will find the average current drain is a lot less than the maximum (you could use your
3A supply to recharge the battery pack, for instance).
Which is not good - servos are not designed to run at full load when static, only when moving,
because they have poor heat dissipation compared to a normal motor (which has a fan spinning
to cool it).
Think about the voltage and current. 9A at 7.4V is 65W or so, which cannot be a continuous
rating for something that size. Thats more heat than a soldering iron.
So clearly the device is meant to run at more like 5 to 10% of max load most of the time.
