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An experimental Magnetic Loop driven by Android and a Stepper Motor - part2

 

So, I wanted to remote control the controller and potentially ditch the digital encoder. I did however manage to debounce the decoder both in hardware with 2 x 0.1uF capacitors across the input pins and 27 Ohm resistors in series with the switch contacts as discharging the capacitors through the decoder is going to damage the tracks and make things worse. I also switched to an ESP32 as it has built in WiFi and Bluetooth. 

Here is the video for this https://youtu.be/pH3pUaQW190

Here are  few of the videos that I took inspiration and code samples (refactored) from-

Kevin Loughin - Magnetic loop transmitting antenna overview and details.

Andreas Spies - Use your Arduino and ESP32/ESP8266 from your Smartphone. No Cloud! (RemoteXY)

                          - #226 ROTARY ENCODER with no switch bounce 🤓 - you MUST use this


From Andreas Spies video I decided this was an easy option rather than rolling my own Arduino app, you can do it for iPhones too. I made a form with a few controls on and was able to connect from the phone to the controller. The webpage at remoteXY.com provides the code for you, so you just have to plug a few variables in. I originally used a slider for fine control but then changed to coarse and fine buttons which increment and decrement the required position 'reqPos' by 5 or 1 respectively. 
I changed the code so that if looks at the difference between reqPos and curPos, the current position and does that number of steps to achieve it. This stops things getting confused so easily.

My code is on GitHub.

The final prototype board assembled and soldered.

rear of the prototype board

Note the two voltage regulators at the top (below) using the blue pins you can select 3.3v, 5v, or 12v (if you have a 12v input). I noticed one of these getting hot driving the motor so I added a 7805 5V 1Amp regulator in a TO220 package, 2 x 0.1uf 50v capacitors for stability and a Red LED and 200 ohm resistor on the 12v rail as an indicator.

Top of the prototype board, note 2 built-in regulators at the top

ULN2003 motor controller, I hot-glued the connections

The circuit, everything between dotted lines was already on the board

I added my own 7805 5V 1A regulator and 2x 0.1uF 50V capacitors for stability an LED and 200 ohm resistor.


I changed the main loop diameter to 2.6 meters and the coupling loop to 0.52 meters. I am still not happy with the SWR as it is around 8:1 unless I use my ATU which defeats the object, but the experiment goes on.

Please leave comments on my videos and I hope that you build at least part of this project.




















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