/diy/ - Do It Yourself

>>1682913
Common-emitter is the way to go friend, put that transistor on the low-side. Also read the datasheet. Minimum beta / hFE for the transistor and 3*maximum relay current will determine your base resistor, maximum current for the transistor (may need to look at heat dissipation values) will determine if it's feasible at all. It probably is, but your MCU/other circuit might not like driving up-to 30mA too much. A MOSFET would be a better choice to avoid having a high base current, or maybe a darlington if you're one of those kinds of people.