Summary of DIY servo tester based on ATTiny85
This article describes a DIY standalone servo tester built to generate RC signals for testing an electric car window motor. The author prioritized simplicity over extra features like an LCD screen, resulting in a compact device using an AtTiny85 microcontroller and a salvaged rotary knob. The project also includes a capacitor to filter noise from the motor and an LED for visual feedback.
Parts used in the DIY Servo Tester:
- AtTiny85 micro-controller
- Big knob salvaged from a radio
- Small capacitor
- LED
Here is a really small side project that I developed while working on something else…
I had to test a RC speed controller that I wanted to use to control an electric car window motor, and for the 100th time I was facing the same dilemma: find 8 batteries for my remote control, dismount the RX part from the quadcopter and use that, OR grab the Arduino and write quickly some code to generate the corresponding signals ? Neither of which was actually particularly handy…
So I finally decided to build a small stand alone servo tester :
The hard part was to avoid trying to squeeze too many features in it, as I kept thinking that having an LCD screen showing the exact pulse width in microsecs would be useful, etc. ….
I finally managed to convince myself that “less is more” and the final design simply has a micro-controller (what else than the trustworthy AtTiny85 !? 🙂 ) and a big knob (that I salvaged from a radio).
Here’s some sort of schema, though that’s probably an overstatement
A, yes, sorry there is also a small capacitor to avoid noise from the motor affecting the MCU (see the lesson I’ve learned here, the HARD way !) and a LED, to give some basic visual feedback, at least when the device is operating.
And here is the simple and clean soldering at the back (I’m becoming quite good at this, it’s almost like a craft: initially how to position the parts to minimize the distances and then how to re-use existing connections to minimize extra soldering… 
), I probably should one day make the leap to design proper PCBs…
For more detail: DIY servo tester based on ATTiny85
- What problem did the author solve by building this device?
The author needed to test an RC speed controller for an electric car window motor without relying on finding 8 batteries or disassembling a quadcopter receiver. - Why was the AtTiny85 chosen as the micro-controller?
The author selected the AtTiny85 because it is described as trustworthy and suitable for generating the required signals. - What feature was considered but ultimately excluded from the design?
An LCD screen showing exact pulse width in microseconds was considered but removed to keep the design simple. - How does the device provide visual feedback during operation?
An LED is included to give basic visual feedback when the device is operating. - What is the purpose of the small capacitor in the circuit?
The capacitor is used to avoid noise from the motor affecting the micro-controller unit. - Where was the big knob sourced from?
The big knob was salvaged from a radio. - Did the author plan to create a proper PCB for this project?
No, the author mentioned they probably should make the leap to design proper PCBs one day, implying they did not do so for this version.
