So I'm working on a project that will utilize ribbon sensors to create a whole bunch of "touch bars". I need them long (~50cm), and I need plenty of them (4-6) next to each other in a narrow space (~45mm), so this kind of stuff form Adafruit won't work, and the cost of longer off-the-shelf devices I've seen around the 'net would blow my budget. (They also seem to be hard to get in EU, and I'd rather avoid overseas shipping.)
This guy did a cool DIY ribbon sensor using video tape as the resistive material:
So I bought some recordable audio tape - can't really tell what is it made of, specs are very scarce, but it's a "Maxell UR". And it doesn't seem to conduct any electricity at all, let alone act as a linear potentiometer. I've checked both sides, with a multimeter, with a battery and a motor, etc, it's just dead like a dead parrot.
I suspect it's either coated with some extra layer, or is using some other technology for the magnetic layer (sadly I couldn't find the text of the IEC 60094 standard that deals with these tapes that wasn't protected by a pay-wall).
What would be my options? I don't even know which kind of tape I should be hunting for, and it was already pretty difficult to find any at all. Should I use video tape instead? Again, which kind?
Any pointers would be greatly appreciated.