A (Short) Lesson in Using Your Eyes

So the PCBs arrived today! I will be fully documenting my testing process and I recently started a new YouTube channel to share more of my progress in a different format, but I will always keep the blog up to date.

Anyways, all went well initially with the PCB testing, the power supplies are not back feeding into the 5V USB C power supply, so the circuit is properly protected. I’m even measuring 3.3V and 12V as expected from the regulator and amplifier circuits.

Where the wins stop however (because I haven’t been able to test any other part yet) when measuring the 180V DC for the Nixie tubes. The circuit does perform DC to DC boost conversion… Just up to 44V rather than the required 180V.

After some debugging, I found that the circuit itself was not the problem, as it was successfully amplifying the voltage. It turns out that when I was selecting components for PCB assembly, I searched for just 0.05ohm, which wouldn’t normally be an issue if you select the resistor category. Instead, I was searching the entire JLCPCB parts library, and when I saw something that said 0.05ohm and had the 0603 footprint I required, I said “yep! that’s the one!” without reading the very important description which read “50mΩ ±25% 0603 Ferrite Beads”.

That’s right, one wrong choice completely changed the behavior of the circuit. The silver-lining of course is that this is a relatively simple fix, I just need to source some new 0.05ohm resistors and replace the ferrite beads on the current boards, and continue on with testing.

I’ll update you all shortly.