Hello everyone and thank you for any help provided.
I'm finishing up my first Arduino project and need some guidance on the final circuit. FYI, I'm not an electrician, but I'm perfectly comfortable working on basic circuits like the one I'm planning. I just want to treat my little Ardunio board right.
So I'm building a coffee roaster using the pid library and some AdaFruit thermocouple breakout boards. I have an lcd interface where I can set the temperature, start a timer, and see some temperatures and other calculations.
My goal is to have a project box with some outlets where I can plug my roaster components into, then plug the box into a wall outlet to power the roaster and Arduino.
I was planning on using a 120v to 5v converter to power the Ardunio, then I saw this: http://www.mlgp-llc.com/arduino/public/tc4-wiring-small-20111120.jpg
They're powering the Ardunio with a ZCD. I've read about ZCDs, and I get the theory, but not really the application. Is it just to avoid interference in digital applications?
Then I confused myself more regarding the relay that will drive the heating element. I've used SSRs with premade Auber pids before, but never realized they had ZCDs in them.
My question is, what applications do you need a ZCD? Also, how do people usually power their Arduinos if they're not using a USB or the power supply?