...the 24V goes off, but slowly... starts with a couple mV then in 3 or 4 seconds goes to zero... what do you think the issue is?

You could try a ~3k resistor from the base of the darlington to ground, if for some reason it is having trouble turning off. If it helps, experiment to find the largest ohms value that works (just to minimize the wasted current).

I assumed you meant the 24V supply is still on, but not activating the coil?

 

You could try a ~3k resistor from the base of the darlington to ground, if for some reason it is having trouble turning off. If it helps, experiment to find the largest ohms value that works (just to minimize the wasted current).

I assumed you meant the 24V supply is still on, but not activating the coil?

I GOT IT!! Well.. It seems that the power supply had some capacitance lol... I put it in the USB and it work just fine!... Now they will just gonna have to deal with the way they will turn on and off this particular port.

Thanks you guy!... I would never got this without your help!...

Rafael