Cheap Idea for a DRO

[irving2008]

Yes I fully agree an experiment is worthwhile.

For proof of principle it seems least effort to try butting two PCB's from two existing gauges together to see if this gives good results across the transition. The infill with solder may be tricky and may cause delamination and a nasty lump. Would it not be better to join down the gaps between T and comb in an L shape machining in the end of each strip.

Re the channel, is it essential to have a channel at all? Providing the reader is in close proximity with the PCB I can't see why it can't work. 0.8 mm (1/32") Shims on the reader half can be used to raise it off the bar.

Another question I have is "is it essential to use double sided pcb"? If the reverse is just plain copper the same capacitance would be achieved by bonding a single sided PCB to a SS bar or Aluminium or a brass bar if you prefer. I'm not sure if the design relies on the reverse plane of the PCB floating electrically from the bar in which case this may explain the need for a double sided PCB.

Good point about the reverse of the PCB. It definitely is some form of ground plane.... might go look in Aldi/Lidl whatever for some cheap ones...