Open Design Engine

I've routed the bias voltage controller PCB and submitted it to OSH Park for fabrication. The PCB file is in the repository, a Parts List will follow in a couple of days.

The bias voltage controller will generate the bias voltage between the probe tip and the sample. It will mount underneath the piezotube, using the same four screws that secure the ceramic holder to the top of the isolator stack.

I also attached some rubber feet to the base

It looks like the guys at OSH Park spotted the inverted drill file, because the boards are fine!

I discovered yesterday that the current version of Kicad has 'mirror Y axis' enabled by default when generating Gerber drill files...which means my base plate cable adapter PCBs will very likely be unusable when they arrive in the mail! So the lesson of the story is, if you are generating a Gerber drill file from Kicad, make sure the 'mirror Y axis' box is UNCHECKED. Otherwise all your holes will be in the wrong places...

I've just spent the morning re-doing all my drill files and checking the Gerber output. So I suppose the other lesson of the story is, check your Gerbers properly before you send them to the PCB fab!

For my first lab journal wiki entry, I've detailed the results of some simulation work done to verify the tunnelling current amplifier design. This work has allowed me finalise the performance parameters and to tune the component values (updated schematic to follow), and has given me some confidence that the amplifier will actually work when it is built. Next goal is to translate the schematic into a PCB...

The base plate has 3 recesses that will house small PCBs. These will adapt the flying leads from the STM assembly to multi-way cables to the control module.

OSH Park are now in the process of fabricating the PCBs.

The tufnol base plate has been made (thanks Dave!), based on the drawing referenced in the previous news post. Next to come are the 3 cable adapter PCBs that fit in the 3 recesses.

See wiki for details