Liam from PCBWay ( www.pcbway.com ) kindly offered to sponsor making some proper PCBs so I've designed a proper PCB with Kicad 6.

So far, I'm impressed with the process. There's a plugin for Kicad that uploads the gerbers in one click. The position and BOM takes a bit more work but it's not a big deal.

I've uploaded the schematic in PDF format. I'll upload an iBOM of the PCB and the gerber files as well.

Changelog from original:

1) Extra capacitance on regulator

2) Ferrite bead on 12V

3) Test points!

4) AC coupling on output

5) Reduced gain stage to x10 as x20 was severely limiting the bandwidth

6) Physically larger so it hopefully drops into an 85x50mm box, directly onto the mounting holes. 

7) Silkscreen!

As the point of this is to be cheap and basic, I ticked the "Allow use of Chinese components" tick box and the only substitution that they made was replacing a Nexperia MMBT3904 with one from Shikues.