Hi all,
I'm after a bit of advise on a fairly unique (I think!) problem. I'm in the middle of trying to make a feeder for small calves, the calves are identified by a rfid tag in their ear, I want to let them have a litre of milk every 6 or so hours. The milk needs to be warm really so I've made a 'warmer' using plastic waste pipe (38mm id) inside 6" waste pipe which forms a water jacket around the small waste pipe, the water is heated and when small pipe is filled with milk, the milk gets warmed. I need to know how much milk each calf has drunk so it needs to be meterd in and out. My first thought was to use a load cell and wiegh the whole thing, I've used load cells before so have a circuit ready designed. However load cells are quite expensive (£120 ish for a good one) I got a cheap half bridge cell from sparkfun, found two resistors of the right value and a INA122 but it doesn't seem accurate enough for my purpose? A ultrasound tranducer is my next thought, does anyone know if a transducer will work in a tube? As I said before its 38mm id, and 80cm long, will ultrasound work or will it bounce off the walls of the tube? The milk will be pumped in so a pressure sensor in the bottom wouldn't work for filling and it needs to be easy to clean! I'm using a 18f2523 as the brain so have a/d, serial comm and I2C avalible and work like to use the minimum number of I/O as I also have soleniods and a pump to control. Hope thats not to rambling?
Cheers Geoff
I'm after a bit of advise on a fairly unique (I think!) problem. I'm in the middle of trying to make a feeder for small calves, the calves are identified by a rfid tag in their ear, I want to let them have a litre of milk every 6 or so hours. The milk needs to be warm really so I've made a 'warmer' using plastic waste pipe (38mm id) inside 6" waste pipe which forms a water jacket around the small waste pipe, the water is heated and when small pipe is filled with milk, the milk gets warmed. I need to know how much milk each calf has drunk so it needs to be meterd in and out. My first thought was to use a load cell and wiegh the whole thing, I've used load cells before so have a circuit ready designed. However load cells are quite expensive (£120 ish for a good one) I got a cheap half bridge cell from sparkfun, found two resistors of the right value and a INA122 but it doesn't seem accurate enough for my purpose? A ultrasound tranducer is my next thought, does anyone know if a transducer will work in a tube? As I said before its 38mm id, and 80cm long, will ultrasound work or will it bounce off the walls of the tube? The milk will be pumped in so a pressure sensor in the bottom wouldn't work for filling and it needs to be easy to clean! I'm using a 18f2523 as the brain so have a/d, serial comm and I2C avalible and work like to use the minimum number of I/O as I also have soleniods and a pump to control. Hope thats not to rambling?
Cheers Geoff