Hello, I am new to electronics so I'm a bit lost when it comes to servos + how to control them.
Here are my 2 questions:
1 . In my project, I want to control 50 Tower Pro Micro servos S90 (9g) with the Arduino Mega. The manufacturer did not give specs about the current output of each of the servos so I'm not sure if I would need an external power source. A friend told me that I may not need external power at all because each of the micro servos draws so little current. Frankly I don't understand this, so I'm asking for verification.
2 . If I do need one, my initial sketch is to connect each servo to a MOSFET and a 1k resistor, then connect all to a 9v battery, but this would make assembly even more tedious. What is a smarter way to do this?
Assume they will take a lot of stall current - normal sized servos can need an amp peak, smaller servos perhaps 0.2A -- 0.5A.
If you want them all to operate simultaneously you will need a hefty supply, perhaps 10A. If only a few at a time you can
get away with less current, but without the specs its pure guesswork - I'd recommend you get a sample servo and measure
its performance.
I don't understand your mention of MOSFETs and 9V batteries - servos are driven with a digital pin via the Servo library, and will need
a separate power supply (nominally 6V). A 9V battery firstly is too high a voltage for a servo and secondly not able to provide the
operating current for even one normal servo. I would imagine you'll need a 6V SLA battery or similar.
What are the 50 servos doing? I am familiar with this model. Moving under light load, the servo will draw 150-200 ma. A stall can push that as high as 800 ma (until it burns out). Resting current is only 10-20 ma.
Remember that these are not high precision devices.