Hello sretaw,
As KlausST has stated, too much current is passing through the inductor. The enameled copper wire
that constitutes the windings of your inductor are way too thin. Plus due to no resistive load, other
than the inductor itself, what ever +12V rail can supply in regards to current, that's what the enameled
copper wire thickness requires to accommodate it.
You really need to check what current is possible through your circuit.
Try placing a 5W or 10W 100 ohm resistor in place of the inductor, then break the circuit and insert a current
meter and measure the current.
Regards,
Relayer