RC Servo Tester - Different Pot

thingiverse

This is a remix of... RC Servo Tester posted by pefozzy on April 04, 2021, here... https://www.thingiverse.com/thing:4817170 The original design is a great enclosure design and circuit. It works as described and provides very neat graphic and digital displays of servo demand position. Adjustment is precise. Unlike the cheap little testers I'm used to, this one will operate the typical SG90 Servos through the full 180 degrees of travel (OK, 178 degrees on the one I used to test the tester). The cheap testers outputs limit the servo to only 90 degrees. The sole reason I remixed this model was to incorporate a more common control pot. The one used in the original was on a small PCB and I didn't have anything like it. My Pot: https://www.amazon.com/gp/product/B07S69443J/ I made a number of relatively modest changes affecting all three of the OP's part models, mainly to incorporate the style of pot I happened to have. The only edits I made not related to that were to change the three holes beneath the pin header to a full slot and to slightly enlarge the "shelf" that supports the non-USB end of the NANO inside the case. I was tempted several times during assembly to make the base deeper to provide a little more room for the wiring, but persevered and made it all fit in the original enclosure. It's the textbook version of the proverbial ten pounds of stuff in a five pound box, but it worked. My biggest fear was that the wires would hold the reset button on the NANO card down but obviously that didn't happen. I used 26 gauge stranded wire with silicone insulation for everything. I've added a schematic. The original posting didn't have one. I was able to work it out from the photos, so no complaints, but the schematic should make wiring it a little easier. All the information needed to set up the Arduino NANO is included in the OP's post. CAUTION: The NANO board is only good for 50 mA per pin and 200 mA total. If you're tempted to use a servo larger than an SG90, don't, or at least assure that the current capability of the NANO is not exceeded. The NANO is relatively cheap but exhuming a deceased one and soldering in a new one is not something I'd look forward to doing. Assembly Notes: Tap all five of the blind holes in the cover with an M3 tap before assembly and assure that the screws will go as deep as necessary before adding the electronic parts. It may be desirable to use M3 split lock washers on the four cover screws as I did. [EDIT 6/3/23 - I should have mentioned that I used an "equal length" pin header, i.e. with long pins top and bottom. That leaves plenty of pin inside the case for the glue to adhere to.] Solder a ~3" piece of wire to each of the 3-pin header pins, then pass them through the slot in the cover from the outside, seating the header in its cavity. Pay attention to the wiring here so that the signal pin is lowest when the tester is oriented with the pot on the right side. Use UV-cure glue or cyanoacrylate on the bottom to secure the pin header to the cover. A bit of UV-cure glue also secures the pot into position. The modification I made to the clamp provides clearance but it does not hold the pot in place, only the display card. Those two places, the pot and pin header, are the only places requiring glue. Cyanoacrylate gel would certainly work just as well as the UV-cure glue. After soldering and heat shrinking the wires to the pot, bend the pins over to about a 45 degree angle to prevent them interfering with the shroud of the USB connector on the Arduino NANO board. Printing Info: Printed with PLA, 0.3 mm nozzle, 0.8 mm shells, 0.15 mm layer height. I don't remember what I had infill set to, probably around 10%, but infill is not much of a factor in this model anyway.