Making A Servo Tester Just A Bit Better

Servo testers are useful devices to have on hand, allowing one to quickly check a given part for proper operation. However, cheaper models can be quite limited, and may not output signals suitable for testing the full range of servos out there. [Buttim] had a few testers laying around, and wanted to see if they could be modified to do more.

Initial experiments with the cheapest model on hand came to naught, revealing nothing but a small IC with its markings scrubbed off. However, going a few more dollars upmarket, [buttim] found a servo tester packing a Nuvoton N75E003. An unfamiliar name to the hobbyist, Nuvoton microcontrollers are often found in mass-production designs due to their low cost.

The N75E003 is a 8051-based device, and [buttim] was able to source a programmer and tutorial resources on how to work with the chip. Armed with the right hardware and knowledge, the servo tester was first programmed with a basic blink sketch. With everything confirmed to be working as expected, [buttim] set about programming a custom firmware for the servo tester that would output a broader range of PWM signals to suit their needs.

It’s a great example of the learning possibilities available by simply cracking open the case of commodity hardware and diving in. Of course, if you need something even more capable, you can always build your own from scratch!

9 thoughts on “Making A Servo Tester Just A Bit Better

    1. The classic “555 vs MCU” dilemma. This little things do have some interesting added functionality: a “neutral” mode, and a “sweeping” mode in which you can use the knob to adjust the speed of the sweeping. You can even change the pulse width to 50, 125 and 250ms. I guess you could do that too with a 555 though…

      1. The 555 can calculate the universe with a well placed potentiometer.

        That said, I haven’t gotten the cleanest signals out of my 555 servo tester, just good enough for what I needed. There are features in the COTS testers I could definitely, but who can say what a true 555 master could accomplish.

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