A friend has asked me to look into making a device for him that will control the on/off cycle of an engine block heater based on outside temperature.
Essentially the heater is a 1KW heater, in an effort to save energy running it all the time, he wanted something that would switch it on and off at intervals that vary for certain temperature ranges.
So, my question would be, can I do something like, connect a relay to the A/C heater and control the on/off cycle of the relay with a DC device controlled by a PIC?
I'm not sure how relays compare to things like BJTs and MOSFETs when it comes to using them as switches. Something simple like switching on/off a LED using a MCU and a BJT is probably different than using a MCU and a relay to switch on/off a 120V AC device...
If what I read about relays is right, then basically a 12V (or so) DC circuit controlled by the MCU would energize an electromagnet and complete a separate circuit that would basically close the connection between the 120V AC main and the heater? If that's true, then the DC circuit and AC circuit are isolated from each other?
Essentially the heater is a 1KW heater, in an effort to save energy running it all the time, he wanted something that would switch it on and off at intervals that vary for certain temperature ranges.
So, my question would be, can I do something like, connect a relay to the A/C heater and control the on/off cycle of the relay with a DC device controlled by a PIC?
I'm not sure how relays compare to things like BJTs and MOSFETs when it comes to using them as switches. Something simple like switching on/off a LED using a MCU and a BJT is probably different than using a MCU and a relay to switch on/off a 120V AC device...
If what I read about relays is right, then basically a 12V (or so) DC circuit controlled by the MCU would energize an electromagnet and complete a separate circuit that would basically close the connection between the 120V AC main and the heater? If that's true, then the DC circuit and AC circuit are isolated from each other?