I'd like to switch a boiler on and off electronically. It is now connected to a thermostat. The first thing I did was measuring the current flowing, closing the circuit with a multimeter set to DC. It is 0.44mA. Then I switched to voltage and measured 90V. I didn't expect such a high voltage.
I was wondering if I could use BC547 transistor, but I saw that limit on collector voltage is 50V. So I think it will not fit. However the current is very small so I don't know.
Do you have any suggestion ? May I still use this transistor, or you have another kind of transistor to suggest? I would use NPN transistors because they are the easiest to use. Would in this case be needed a different kind of transistor?
UPDATE @ Dave Tweed: Good point the AC. I closed the circuit with my multimeter set to AC. I got 120V and 0.6mA. Now I don't know any more if it's DC or AC.
@ markrages: NPN transistors, as long as I have read are easier compared to PNP. What do you mean when you say they are not easy? Compared to what? I'm afraid I don't get the sense of your sentence.
@ George Herold and @ Peter Bennett: A relay is easy to intall and certainly working for my project. This is why I'm asking about transistors. However, I didn't consider the circuit isolation point, which I consider very valuable information, since I really don't know anything about the remote circuit. I just have 2 cables and I know that if I connect them the boiler powers on. The reason why I am asking about transistors as an alternative to relay are the following Relays are more expensive, more noisy (chatters), larger, more power demanding.
So I renew my question: Does it make any sense to use a transistor to electronically turn on and off a remote circuit with the current characteristics outlined above? In case nobody has any suggestion for this question I'll certainly use a realy as suggested.