I know its been a while but I'm having problems with this circuit, the major one is that when the transistor brings the trigger to 0V for more than 6 seconds the output remains high. I know the circuit works because if I send voltage to the transistor the timer outputs 11v for 6 seconds. Another problem, but not that major is the transistor is too sensitive, meaning that even if I just touch the base (2n3904) with my finger it triggers, so I think I would need a way to stabilize and filter it. One more thing I used a 6.2k instead of a 6.8k on the base, I don't think it makes that big of a deal but U never know. Thanks.