# Relay closes without load connected across its terminals but doesn't work when it's loaded

why would something like that happen? all the relay has to do is to close its contacts, what difference would the load do?

• What powers the load? – jonk Dec 24 '16 at 0:32
• @jonk AC mains 220v ac – iMohaned Dec 24 '16 at 0:46
• You might want to define "doesn't work" with something more descriptive. Assuming there is no galvanic connection, I'd also be curious about what your AC powered load actually is. And also curious about the current required by your 12 V relay (though I don't expect that to be more than $180\:\textrm{mA}$.) – jonk Dec 24 '16 at 1:00
• Consider redrawing your schematic diagram. The section driving the relay is especially problematic. It is difficult to read, with the battery at the bottom. A first glance says "the diode is upside down" followed by "what's driving the relay" followed by " oh, geeze, its all connected right but what mess." – JRE Dec 24 '16 at 10:15

• I agree about $R_3$. I'd anticipate that the total collector load on the BJT is around $200\:\textrm{mA}$ from what I see there and guessing about the relay. That's a lot to expect from $400\:\mu\textrm{A}$ base drive current. – jonk Dec 24 '16 at 1:03