Eariler, I linked this ETO article https://www.electro-tech-online.com/threads/parking-sensor.291/,that shows how to configure a 555 as a bistable latch. Now, if the output of the latch is fed back to the input of the 1-s delay timer, along with the original trigger, you can make the 1st timer a one-time-only triggered timer. For example, a 'low' (<VCC/3) signal triggers the 1st timer, so the normal trigger would be combined with the feed back from the latch by, say a logical OR gate. In that way, it would take both a trigger voltage from the sensor, and the latch not activated to trigger the 1st timer. Once the latch is activated, the 1st timer could no longer be triggered, until power is removed.
Sorry, don't have my schematic software ( I'm @ work at the moment )
(yes, I read ETO at work. everyone needs a break )
Sorry, don't have my schematic software ( I'm @ work at the moment )
(yes, I read ETO at work. everyone needs a break )
Last edited: