My level of electronics is very basic and due to your suggestion I studied a little about relays (I admit that I should read more). THANK YOU SO MUCH.
I understand that they work to turn a component on, to turn it off, and also to increase and decrease power, right?
I know it works to turn it off and on, but I still don't know if it works to increase the power, that is, to make the peltier cell consume more or less to regulate the temperature little by little. (I'll be investigating while you answer).