1) Thank you. There must be something I don't get, which isn't surprising.
I thought pin 4 and also pin 2-555 (direct to pin 2) would go high and (while pin 1 is still low) keep 3 high for the duration of the drop from the sensor at pin 1, as in the schema.
But then I dont see how the C7, R13 is helping (see the picture). If pin 3 stays high, what is C7, R13 achieving?
It still looks to me as if the pin 3 duration is controlling (via pin 4) the 555 output, even tho your schema is different..
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2) If the 555 gets a persisting drop at its pin2, the 555 output stays On till that drop ends. That has been the problem. (Your schema is not like this, I accept)
So keeping the 4093 pin 3 high, will keep the signal to the 555 low and 555 output stays on. ?????
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3) Is the problem of light "staying on" at the 555? Should pins 4 and 8 be getting power without a resistance as in the original diagram (page 6 here)? Could it be damaged? (I replaced it but that wouldn't help if it blows at once)