Here is my loop remote control electronics board. Not a PCB, but a 3D printed mount for all the electronics modules.
As described earlier, I am building a multi-turn transmitting loop as an Internet of Things (IoT) project. Rather than designing a circuit from scratch, as done previously, I am crafting a control system using available modules. As you can see, these are mounted on a plastic structure that will be mounted inside the rotator.
On the left is the NodeMCU microcontroller with a WIFI system-on-chip. My project brains sits inside a motor control shield, which is screwed to my remote control electronics board. This shield runs the high-torque geared DC motor using the green-white wire pair coming off center left.
Look at the upper right. The square board is the ULN2003 stepper motor controller for the tuning capacitor. Four of my NodeMCU digital pins run stepper speed and direction.
On the lower right is a voltage regulator module which splits off a 5 VDC power bus from the 12 VDC master. I need 5V to run the NodeMCU and the stepper and 12V for the DC motor, so my arrangement should work well. I expect to draw less than an amp.
At the very top is a plastic 12 by 2 terminal strip for most of my wiring interconnections. All the modules are mounted using short machine screws, either M3 or 4-40, with captive nuts inserted into hexagon holders on the back side of the plastic structure.
Remote Control Electronics Board Challenges
Structures like this are easy to design in CAD and 3D print. My terminal strip enables a highly modular approach in case I need to replace or repair components without total disassembly.
I found the biggest challenge was the screw terminals on the cheap LM317 voltage regulator module. These are really flimsy and hard to adjust without stripping the screw head. Also, they don’t easily allow insertion and capture of wires. I recently recycled a bunch of (really) old PC and kept a lot of the old wiring for projects like this.
Now that I have everything wired up on the workbench, it’s time to write some code for remote control.