on-off machine
nounUK /ˌɒn ˈɒf məˌʃiːn/
US /ˌɑːn ˈɔːf məˌʃiːn/
A machine that can be switched on and off.
The little on-off machine makes the toy robot walk.
OTHER MEANINGS
2. A device that only has two states: working or not working.
This on-off machine has no middle setting.
3. A simple mechanical toy that starts and stops.
He played with the on-off machine for hours.
4. A person who quickly changes between being friendly and unfriendly.
My neighbor is an on-off machine when it comes to saying hello.