on-off robot
nounUK /ˌɒn ˈɒf ˈrəʊbɒt/
US /ˌɑːn ˈɔːf ˈroʊbɑːt/
A robot that can only turn on or off, not do anything in between.
The little on-off robot just blinked its light and stopped.
OTHER MEANINGS
2. A toy robot with just two buttons, one for on and one for off.
My brother got an on-off robot for his birthday.
3. A person who only reacts in extremes, either full of energy or completely still.
After the long trip, he was like an on-off robot, awake one minute and asleep the next.
4. A machine that alternates between two states without any middle setting.
The old heater was an on-off robot, blasting heat and then going silent.