I remember a series that I liked in the 80's. It was about a group of children that may have lived on a farm. They found pieces of machinery in the local countryside which they found fitted together. It definitely had a sci-fi type feel to it and was a live action show.
I think the series was probably on after Newsround for 20-30mins. It may have been an import.
I never saw all the episodes, sorry for being vague. Also I never saw an ending if there was one.
EDIT
There was maybe a swamp where they found a ring of the device Also there was a girl and boy and possibly another character other than family members (mum, dad etc)