I've had servo testers in the past but they've always had an on-board battery, however I wanted a decent one so I got myself a Turnigy servo tester which can test 3 servos at once which obviously saves a bit of time.
The only downside too the better models is they need external power via a servo socket connection. The Turnigy "CCPM servo consistency master" allows you to manually operate the servos via a knob control. Also via a little control button you can set all servos their center position and lastly "auto" which constantly keeps the servo in motion turning it each way to maximum position then going back.
The tester unit accepts 4.8-6 volt input so while looking through my cable box which is a headache
it clicked in my end I could use a USB output being 5-5.5 volt output it's perfect and doesn't require a battery pack!People asked how this would work at the field, the answer is simple where I go my laptop goes and that includes the field to transfer photos from the camera and record FPV flight video stream from the 5.8Ghz receiver unit.
So what do you need to do? check it out below, click the picture to view full size image:
Strip one USB cable down too its inner 4 cables which are usually Red, Black, White and Green OR blue. You only need Red and Black so cut back the other 2 to the very stub of the wire and tape it off. Now to state the obvious black is negative and red is positive.
For the servo lead end use the bottom 2 wires of the 3 when plugged into the servo tester (most indicate on the tester the polarity wire layout)
. Middle is positive and bottom is negative, simple solder each of the wires together and tape off OR use heat-shrink pipe depending how tidy you want it
Now you can plug it in and start testing servos without the headache of batteries
Score +1 for USB hehe...