Hi,
Arduino PWM works at 5V signal. Is this right?
The servo that i use works at 3V PWM signal.
servo: Hitec HS-985MG works at:
3v PWM signal peak to peak from 900uS to 2100uS with 1500uS as neutral.
Thanks
Yes
Transistor
Yes
Why a transistor?
What's wrong with a potential divider?
We're only talking simple signal levels here.
I think you will find that bartuino is sucking you into a programming issue that is contained in the below discussion.
@AWOL: Hay, I'm a 12 year old noob who has never touched a servo... I'm just speaking my thoughts...
Arduino PWM works at 5V signal. Is this right?
The servo that i use works at 3V PWM signal.
servo: Hitec HS-985MG works at:
3v PWM signal peak to peak from 900uS to 2100uS with 1500uS as neutral.
The Hitec HS-985MG servo works with standard servo voltages of 4.8 to 6vdc, not 3v. Servos use PPM signals, not PWM.
http://www.hitecrcd.com/products/servos/analog/premium-sport/hs-985mg.html
Again the That Hitec serso is not rated at 3vdc service, so control signal voltage should be 5vdc.
Show us your complete sketch code and a wiring diagram of how you are controlling and powering the servo and only then can we really help you.
Lefty
I would guess that the 3v Hitec signal spec is refering to the minimum voltage that the input signal needs to be. I don't know what the signal output voltage peaks are for the R/C receivers they are normally used with. I do know that the Hitec servos work quite well with 5v signals supplied from various servo controllers. The person requesting the info really needs to contact Hitec to get the qualified answer. Any answers here will probably be speculation.
Here is the Hitec spec page for that servo
Nothing about 3v that I can see. It gives specs for operating at 4.8v and 6.0v, and every Hitec servo (a hundred or so of many different models) that I have used uses a signal voltage at the same as the power voltage.
Hook it up to your output pin. Power it from a separate source and tie the ground to the Arduino ground.
Use the servo library to attach the logical servo to the same pin that the physical servo is attached to.
Watch your servo move to the command of the Arduino. 
Wow, what a action! Sorry, but i whas not connected for a few days.
All thanks for answers.
Here we go:
@zoomkat
Yes, after a search and few tests i have moved to the software section.
But your right i have not explained properly, this 3V PWM signal will be the minimum.
@retrolefty
software:
"standard firmata" with Maxuino 009 Max patch.
But this i post this better in the software section, i think?
hardware:
servo to Arduino connection:
AC to 6V DC 2000mA powersupply -> negative lead (black) -> Arduino ground
Servo black wires -> Arduino ground
Servo Red wires -> AC to 6V DC 2000mA powersupply positive lead (red)
Servo yellow wires -> servo signal pins (Arduino digital pins 9 & 10)
I think so, but is this ok?
@vinceherman
The technical service from Hitec has send me a mail to say that it has to be 3V PWM signal.
But like zoomkat says, it will be the minimum.