PID controller to maintain temp, need guidance choosing components

Hi, I’m going to implement a PID controller to control the temperature of the air inside a box/electronic enclosure or anything else that I decide to use, I’m going to use and control a heating element and a fan to keep the temp inside the box at 50c or close to it. Now below are the components I am planning to order, if you do have any suggestions, that would be appreciated. Please note there is no other restrictions on the type of components, power consumed or anything else.

Box: The dimensions I’m looking for is more or less Length: 200mm, Width: 150mm, Height: 150mm. Now I’m planning to buy a simple electronic metal enclosure that allows some air in, then I will need to cut the top of it to install a fan and some other holes to allow in the heating element, is there a better option than electronic metal enclosures?

MOSFET: Will be used as switch to turn on/off power supply to heating element and fan.

Heating Element & Fan: I am lost at choosing a heating element, I’d rather use 12V DC that doesn’t draw too much power, almost all options out there are 220V AC(UK) and there is a lot of them, I really don’t know what to choose. I haven’t looked at the fans yet but that’s probably going to be a 12V DC fan that I can change its speed.

Temp sensor: At the moment my choice is LM35 because I have one, other options are thermocouple or thermistor.

And of course some other basic stuff like resistors, diodes, capacitors and etc. Am I missing something ? anything needed for safety measurements ?

What is Your really needed temperature intervall, the accuracy for 50 degrees? Asking for not needed precision only cost money and efforts.

What power would the heater need to provide? Drop the demand for 12 volt and look at the power needed. How fast does the temperature need to reach the target? How accurate does the the temperature level really need to be?

For the heating element, it is safer to stay with [u]low voltage, high current[/u] heating configuration than [u]high voltage, low current[/u] since high voltage is more than likely to kill you if you made a mistake.

Railroader: What is Your really needed temperature intervall, the accuracy for 50 degrees? Asking for not needed precision only cost money and efforts.

What power would the heater need to provide? Drop the demand for 12 volt and look at the power needed. How fast does the temperature need to reach the target? How accurate does the the temperature level really need to be?

It's more like an experiment to see what accuracy I can achieve using a PID controller, so I literally have not been given any sort of restrictions or requirements about this project, even the 50c is my choice. I might have had an easier time choosing components if there were requirements, how long would you expect a decent but not expensive 12V heating element to heat up the air inside the box(dimensions in the original post) to 50 degrees ? Like I said it's less about the accuracy and more about exploring PID controllers and what it can achieve.

is there a better option than electronic metal enclosures

An INSULATED enclosure.

It will be faster to heat, easier to control and require less energy to maintain temp.

hzrnbgy: For the heating element, it is safer to stay with [u]low voltage, high current[/u] heating configuration than [u]high voltage, low current[/u] since high voltage is more than likely to kill you if you made a mistake.

Thank you, what current range would you suggest me to look at considering I do not have to worry about any project requirements, ideally I would like it to heat up the air inside the box(Length: 200mm, Width: 150mm, Height: 150mm) to 50c in less than a minute but safety is the priority. I don't think I will be able to find any heating element requiring less than 12V, I haven't found a single one.

Nichrome wire can be used to make heaters that work with any desired voltage.

High wattage power resistors and incandescent light bulbs make fine heaters, and are available in a very wide range of resistance values (voltage for bulbs) and power dissipation.

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Figure out the power required to heat the enclosure before you do anything else.

jremington: An INSULATED enclosure.

It will be faster to heat, easier to control and require less energy to maintain temp. Nichrome wire can be used to make heaters that work with any desired voltage. Figure out the power required to heat the enclosure before you do anything else.

Thanks a lot, I will look for the insulated ones, great advice. I have come across Nichrome wires, might be my best option considering the box is not large so I think it could do a good job heating the air inside.

Right, I will try to find out what power would be needed for the enclosure with the dimensions I mentioned above.