I'm an IT guy, but have lately started working more and more "on the edge" as we say, so close to the real world and with low level sensors. I'm currently building a liquid throughput sensor and reading it with a raspberry pi to send it to a server.
These are the specificiations for the sensor:
2500Imp/L at 20°C
0,05 - 3L/min
using a Hall sensor principle
The link to the product would be this OHS3040U: http://www.kynix.com/Detail/64233/OHS3040U.html.
It is from the TT electronics: http://www.ttelectronics.com/en/home
I can read the pulses using a pull up resistor at the signal with 3.3V and 2kOhm. But there are two problems:
when I squeeze 60ml through a syringe into the sensor I get about 300pulses == to 120mL with a deviation of about 10ml (tried 10 times). Did I calculate something wrong? I'm listening for "falling edges" so I count every time the voltage drops to 0V.
It often doesn't work, and if it works, it does so best when in a horizontal axis, so reading pins up, liquid in/out on one level. Is this normal for these flow sensors?
as you might be able to tell I'm used to software, not hardware so treat me like a first year engineering student if you want.
I'd greatly appreciate your help! Greetings from Germany
P.S. its for a cow milking battle where we want to have several participants milk a fake cow and see who's the fastest. We want to measure on a 1/10sec precision and visualise the data throughput/second for 120seconds
I created an image of my setup. however I used 5x 10k Ohm resistors in parallel since I don't have 2.2kOhm Resistors. the image description is here: