/diy/ - Do It Yourself

>>1541133
Oh now that I think about it, that method would be somewhat difficult to design since the iron ball would be quite heavy and wouldn't be terribly suited to measuring a wide range of air flows (too large a ball means it won't measure low flow well, too small a ball and the hole itself will need to be small and won't let large flows through), plus the problem with an induction hob. So if I instead use a large (20mm diameter perhaps), hollow stainless ball in the rotameter and have two parallel plates on either side of it, I could measure a very drastic change in capacitance as the ball in the middle acts like a short between two middle plates (pic related). The ball would be much lighter and the capacitive system wouldn't be affected by magnetic fields.

To avoid hysteresis problems, this couldn't work very well with a hob with high heat capacity, so basically a gas hob or an induction hob would be the only way to go, though an electric frying pan (or other all-in-one cooking vessel) would probably work fine. A gas hob would be pretty hard to control, I wonder what valve you could use to linearly alter the gas flow, apart from a servo on a ball valve/globe valve.