Servo tester
ajkumar-1907·power-converter-lib·servo-tester/servo-tester.kicad_pcb
About the Servo tester PCB
Servo tester is an open source PCB design by ajkumar-1907, published on GitHub under the MIT license. It is a 2-layer board measuring 30.5 × 27.8 mm, with 10 components from 10 distinct parts.
Other key parts include the NE555P. By type, the board carries 3 resistors, 2 connectors, 2 diodes, 1 IC and 1 capacitor.
It belongs with the robotics & motion designs in this gallery.
From the project
Open-source library of power electronics converter topologies — KiCad schematics, working principles, use cases, and design notes for DC-DC, AC-DC, DC-AC, and AC-AC converters. Free to use, modify, and build on.
A standalone servo tester built around an NE555 timer. It generates the PWM control pulse a hobby servo expects, and turning the potentiometer sweeps the servo through its range. No microcontroller or code is needed.
Hobby servos (SG90, MG995, etc.) set their shaft angle from the width of a repeating pulse: about 1 ms for one end, 1.5 ms for centre and 2 ms for the other end. This board makes that pulse with a 555 in astable mode. A steering diode separates the charge and discharge paths, so the pulse width (high time) and the gap between pulses (low time) can be set independently. That lets…

Main components on the Servo tester
Servo tester bill of materials (BOM)
10 components, 10 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | NE555P | DIP-8_W7.62mm | U1 |
| 1 | Conn_01x02_Pin | PinHeader_1x02_P2.54mm_Horizontal | J1 |
| 1 | Conn_01x03_Pin | PinHeader_1x03_P2.54mm_Horizontal | J2 |
| 1 | 100K | Potentiometer_Alps_RK163_Single_Horizontal | RV1 |
| 1 | 1N4148 | D_DO-35_SOD27_P7.62mm_Horizontal | D1 |
| 1 | LED | LED_D3.0mm | D2 |
| 1 | 22nF | C_Disc_D4.3mm_W1.9mm_P5.00mm | C1 |
| 1 | 3M3 | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R1 |
| 1 | 56K | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R2 |
| 1 | 1K | R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R3 |
Servo tester design files
The KiCad project lives in the ajkumar-1907/power-converter-lib repository on GitHub; these links point at the commit this page was built from.
Servo tester: common questions
How big is the Servo tester PCB?
The Servo tester measures 30.5 × 27.8 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the Servo tester?
10 components, from 10 distinct parts. The full bill of materials is listed on this page.
Where can I download the Servo tester design files?
From the ajkumar-1907/power-converter-lib repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Servo tester design in my own project?
Yes, under the terms of its MIT license, which ajkumar-1907 chose for the repository.
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