I'm using a Hitec HLS12 series linear servo (4.8-7.4V) with an Arduino Uno. I have the servo powered by an external 6V battery. It works fine right now with the Uno directly connected to the control wire of the servo. I'm not too familiar with servos or motors in general but I was told I might need a switching transistor to increase the current.
I was just wondering if I actually needed to since it's working pretty good as is. The speed I'm getting is about the same as specified on the product page.
I have a 2N7000 MOSFET and should have some BJTs lying around if it is recommended.
The only need for a transistor is a too high idle voltage on the servo control pin. Disconnect the Arduino and measure that voltage vs. Gnd. It should be not higher than the controller operating voltage, else the servo is out of the RC model specs.