Reviving a hardware project often means revisiting past designs-and sometimes, embracing the lessons they teach. After months of redrawing schematics and PCBs in KiCad, the latest iteration of my automatic magnetic loop tuner’s controller has emerged with critical fixes and a back-to-basics approach. Here’s where things stand.
Fixing the Teensy 4.0 Protection
The initial design had a glaring oversight: insufficient protection for the Teensy 4.0’s input pins against voltage spikes above 3.3V. Teensy 4.0 pins aren’t 5V-tolerant, and accidental overvoltage could brick the board. To solve this, I integrated BAT54S Schottky diodes on vulnerable pins. These diodes clamp incoming voltages by diverting excess current to ground, acting as a safeguard. Schottky diodes were chosen for their low forward voltage (~0.3V), ensuring tighter protection compared to Zeners or TVS diodes.
Embracing THT Over SMD
I ditched the idea of preassembled SMD boards for through-hole (THT) components. Sure, SMD saves space, but for a hobbyist project, the joy of hands-on soldering and the ability to pivot designs on the fly outweigh miniaturization.
Lessons from Copy/Paste Errors
The first PCB’s flaws stemmed from rushed copy/paste actions in KiCad-a reminder to double-check symbol footprints and netlists. A misplaced capacitor or reversed diode can derail weeks of progress. Now, every component is verified against datasheets before layout. And checked for the correct value before placement.
What’s Next?
With the new PCB undergoing tests, the focus shifts to coding the LCD backlight adjustment and 1/32 microstepping logic. After that, integrating an SWR bridge into the controller will pave the way for real-world tuning trials.
Sometimes, stepping back to THT and manual soldering isn’t just practical-it’s a return to what makes hardware hacking fun: seeing a circuit come alive, one through-hole lead at a time.
Also, a big thank you to Ton PA0ARR, and the members of Amateur Radio Club MLB and HAC for their advice and patience to teach me something new about electronics 😉