RC Digital Servo Tester 1 Channels Motor Servo Controller Centering Tool with Over-Current Protection & 2 Control Modes for RC Car Airplane Robots...

working fine as expected

It does ok, but my cheaper older servo tester has 3 functions, with the 3rd being it continuously sweeps the arm back and forth, but this new tester doesnt.

Needed an easy way to set up servos and test, this worked just fine, worth the time it saved to make up a temporary solution, and I can test servos easily whenever I need to. I cut the USB 2.0 B end off a cable, wired up +5v and Gnd to this board, and plugged into a 5V 3A USB 2.0 adapter, worked great. I haven't checked the signal timing / accuracy, but it should be good enough. Operation - the buttons set the servo to "center" mode, causing the servo to immediately move to center - if you press a 2nd time, the servo will immediately return to the position dictated by the potentiometer. Only way it could have been better would have been to have a USB cable for power.

I like that it can be powered from the balance plug of a lipo battery or you can connect a power supply or connector to the handy screw terminals for power. The digital readout tells you the power supply voltage. The push-button lets you select either 'middle of travel' mode or control by the knob. There is no 'auto' mode, but it is great for testing a servo or setting up travel when installing one. You can control two servos at a time, they are slaved together. This is a simple device, it works well and was very inexpensive. You should probably cover the bottom of the board to prevent accidental shorts from metal on your workbench. I glued a piece of plastic on mine. For the money, this is a great little device.

This works well for testing range of motion for control surfaces of DIY RC planes as well as centering servos before installing pushrods. Several things to note if you're using with the smaller RC micro servos: 1. You should not plug in a LiPo battery to power the tester and servos unless you are positive that the servos can handle higher voltage. Typical micro servos (eg 5g/9g) operate with a maximum of 6V, so if you use a 2S Lipo you are exposing them to 7.4V or more, which may fry these smaller servos. Instead, you can use wire leads to connect the + and - terminals from an ESC to the blue power input block on the tester. I soldered some leads to a normal USB plug and was then able to use a cheap portable USB power bank to power the servo tester at a perfect 5V. 2. The tester outputs from 500 - 2500 s, whereas the typical operating range for servos is 1000-2000s. Just be aware that turning the potentiometer knob to the ends of its motion may send a signal that is beyond the operating range of the servos; you do not want to keep a servo locked beyond it's maximum range of motion for long.