Mission Possible

Q: Regarding the recent rule clarification: Timer can not have an electrical sensor ending it.  Would you please explain how this rule apply?  For example, if an hourglass drop sand and does measure the weight of the dropped sand with a electronic scale would not qualify for a timer?   If it trigger a switch, does it qualify for timer? (or does a switch consider a "sensor")   If a IR photo gate is used, does it consider a sensor?  If a counter is used, does it consider a sensor?    Furthermore, if the sensor is not used to ending it.  As a color sensor is monitoring the color to see if the color changes,  Does it consider a "sensor ending"? (section: 4 / paragraph: g / sub-paragraph: i / line: 1)

A: The timer cannot be adjusted by electric or electronic means. For example, a sand timer which pours sand onto a counterbalanced lever, which triggers a switch when there is enough sand would be acceptable if the timer is adjusted by changing the weight of the counterbalance. However, a sand timer which pours sand into a container which has a weight/pressure sensor with an Arduino would not be acceptable if the timer is adjusted by changing the threshold (via the Arduino's program, a potentiometer, etc.)