Yes, but I think you would need something to allow for the fact that the '555 output won't fully reach the supply voltage - a potential divider or a series zener perhaps.I don't see why you need the transistor to invert sense of the drive to the opto coupler. You could just connect the opto coupler in series with its current limiting resistor between the output of the 555 and the positive rail.
Les.
Hi
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