Rev PCB

[Vannue007]

Hi @klemetsson,

I've just received some Pi zero 2W's as they start to be available again. I've found your Project last year but without the ability to buy Pi zero pu t this on close monitor.

Now I want to do the same and wanted your opinion on whether your PCB design works fine as I'm planning to order 2 PCB's to replace my bulky Pi 3 stratux combo to a more compact version. Thanks

[klemetsson]

Hi, it's still a work in progress and there are some issues on the PCB that I will adress. Unfortunately I've been a bit busy lately but I want to get around to fix it.

Things that are tested and works:

• The software finds the SDRs correctly
• The GPS works
• The AHRS gyro/accelerometers work
• USB power/charging and battery (however haven't evaluated the battery life I would get on the single cell)

There is two major design issues with the current PCB revision and a few minor.

1. Leakage current from the 8051 i/o pins are enough to partially start up the 5V regulator and cause it to give invalid voltages. I "fixed" it on my board by adding a resistor. Hopefully it is visible in the image.

2) The feedback on IC5 is to close to the inductor L2 and caused some issues. Moving the inductor slightly await from the IC fixed that issue.

Things that could be improved:

• The two SDRs get really hot and that heat is transferred through the connector to the ground plane, heating up the battery. Could probably be solved by adding an external heat sink on the SDRs and USB connectors.

• When charging, the 5V turns on with cause the SDRs to turn on even though the Pi is not booted. This can be fixed by adding USB power switches that the USB hub can control.

Things that haven't been tested yet:

• Carbon monoxide sensor
• The fuel gauge to get the power remaining and adding a low battery warning.

Hopefully I will have a new revision sometime next month.

[Vannue007]

Thank you for the update. perhaps it's better to hold off the 2 pcb's (1 test & 1 working) I wanted to make in the next evenings. I'm anyway busy with converting the standard old stratux assembly to a compact pi zero assembly. so it will be for September ;-) and then I can use the nano3 SDR from Nooelec of which has the additional heat sinks.

Are you planning to re-utilize the same components? perhaps I can do additional tests during the next months and start sourcing those of which I'm lacking now.

Anyway, it's a super project you've created.

[Vannue007]

If allowed, I’m planning to revise the pcb by myself in the next 2months with the suggestions you’ve mentioned. Did you use Altium for the design?