Hi, I am building a 555 circuit to trigger a relay to source a 30 amp 120v load. I am wondering how to use a transistor on the output(pin3) to power the relay if neccesary. I also need the duty cycle of the relay to be variable from about 500 mSec to 2 Sec, can a relay handle that? Any thoughts would be helpful. The circuit is to control a small homemade spot welder.