Hi all,
First of all, I am a complete rookie when it comes to electronics, so please be patient.
Here is the project that I want to play around with.
For some home cheese-making I need to be able to heat milk to a fixed set-point of let’s say 32 degrees. Even more important is that I am able to keep it at this set-point for a fixed period of let’s say an hour. (the temperature and holding time depend on the recipe).
My idea is to make a au bain marie heater, that is, one pan of water with a heating element. Inside the pan of water a place the pan with milk. I am not sure yet whether to use one temperature measurement (either in the water or in the milk) or use two. This is something I will probably find out in practice.
Basically this is how I work now, but I do it on a stove and control it all manually, which is a lot of labour and error-prone./inaccurate.
So I am playing with the idea of creating something automated with a K8055 USB interface card.
For heating I would like to use a “standard” 220V immersible heating element. How many Watts for the heating element will depends on the dimensions, so I haven’t determined that yet.
My gut feel tells me that a simple on and off control will not be accurate and will result in lot’s of switching. So I would like to be able to control the power of the heating element from 0-100% with a PID controller.
The software and PID controller I think I will manage (after some trial and error…). But how would I wire a temperature sensor and the heating element. I assume that to control the power of the heating element, I would need to change either the current or the voltage (if I remember correctly, P=V x I). How would I do this?
Hope I make my problem clear, any help is welcome!