Some RCX400 internals images

Roger Hamlett wrote in message ...

I was thinking of the relative encoders, not absolute units. If you look
at the designs used on digital vernier calipers, these use a pair of PCB
strips, with fractionally different pitches, to produce a sinusoidal
coupling change as the strips are moved relative to one another. Since the
signals involved are low frequency (normlly 32K 'watch' crystals), you can
run the strip continuously, using a 'watch' battery. I use these in a
system here. The strips cost less than $2 in PCB 'real estate', and the
detector is an off the shelf IC, costing $1.65. These give 0.0005"
position detection, and finer strips can be made if needed. This in 10 off
quantities.
Best Wishes


I'm interested in which is the off the shelf $1.65 IC that does the digital
caliper function . If you know the chip maker, vendor, distributor, chip
designator , would be greatly appreciated.
Most of these work based on patents owned by Mitutoyo , I wasn't able to
find any standard part for the function.
While the electrodes configuration is something that can be circumvented due
to multiple layout possibilities, I don't know of any Western IC maker that
has an IC for this .
I have seen Chinese copies but the chip is bonded to the pcb directly so no
way to identify it . I have worked with more high end devices from Renishaw
and Heidenhain but they're in a much higher price class.

best regards,
matt tudor