I am making a food dehydrator that will be on 4 wheels. I want to be able to weigh the dehydrator plus the contents as it dries. When the desired weight of the contents is reached, I will know that the food is dehydrated thoroughly. Is there any way to use sensors with an arduino to do this? Would I have to put one sensor under each wheel, or is there some way to keep all of the hardware in/on the dehydrator?
I guess it would depend on the shape of the dehydrator. Could you "suspend" the food from a single point?
Before you go too far, you should try to calculate the range and resolution you need for the weight sensor to provide satisfactory results. Low cost <$100 - $200 sensors have a horrible drift. This drift is mostly a zero offset, still over 10+ hours the readings of a low cost sensor will make the results useless.
The HX711 and an amplifier are the load cells weigh items. Make a roll-on platform, get the tare weight, then find the difference.
1 Like
What do you think will be the weight of the whole unit?
How much weight do you think the water in the food will weigh?
(Weigh a sample before and after dehydrating)
If the machine weighs 10kg and the water content weighs 10g you are unlikely to get very accurate readings.
Yes you would need at least three sensors and probably 4 to prevent measurement errors due to misalignment with vertical.
Yes - but how depends on the physical arrangement - can you provide a sketch?
Thank you for your helpful responses. The dehydrator itself is likely to weigh 70 pounds. I don't yet have a sketch - still playing around with variables - but imagine a cabinet 60" tall, 24" deep and 48" wide - a big box - and you will have a very good idea of what it will look like. It will be on 4 wheels. Vegetables and fruit are 80%-90% water, so if I put 50 pounds of fresh potatoes in it, it would at first weigh 120 pounds. When it was "finished" dehydrating, it would weigh about 80 pounds - yes, I was hoping to be pretty accurate. I can also use the duration of dehydration to test, but weight would be a much better indication of when it was finished.
A sensor to measure the relative humidity of the exhaust air stream would be more accurate and easier to monitor.
2 Likes
I would say on top of each wheel, between wheel and dehydrator. Four sensors wired in Wheatstone bridge and HX711. Since your measurements are static, I don't see big issues. But measuring relative humidity, like @Paul_KD7HB wrote, is much more simple and also accurate. Just stay away from those DHTxx sensors, with few bucks you get SHT31.
Yes, you can use load cells with an HX711 module and Arduino to weigh your dehydrator and its contents. Either use one load cell for the entire unit or place one under each wheel and sum the readings. Calibrate the setup, and you can monitor weight in real-time to ensure proper dehydration. 