I hunted around for applicable flow sensors. Unfortunately, my requirements are rather awkward - the basic problem being a very small flow rate.
At some point I gave up the search and decided to make one myself. If I may say so myself, I am quite pleased with the results. It uses an IR detector and emitter to spot gas bubbles in a small water-filled container, and an Atmel microcontroller to do the measurements and a degree of signal filtering. Finally it uses a DAC and op-amp to provide the voltage required by the DrDAQ. Because of the resultant high current requirements, a mains adapter provides a parallel power supply.
Having got this far, I finally commited myself to buying the DrDAQ itself. It's an excellent piece of kit and does everything I want, except I cannot get it to recognise my sensor.
Last night I tried a using simple dummy sensor built from a 2K2 resistor and a 100K pot. Even this didn't seem to be recognised by PicoScope (5.08). The calibration file (bubbpers.dds) looks something like this:
When I try to use either my bubble sensor or the dummy, the Y-axis of the scope appears without the correct label and a simple 0 to 100 range. Can you help?