Goalkeeper joins non-league side.
Carl has spent a number of spells out on loan at other clubs, including near neighbours Chelmsford City.
And he will join Histon for a month to get some first team football under his belt.
He will join U's team mate Ben Coker at the non-league club, although Ben's initial month is due to come to a close this weekend.
The U's faced Histon in a friendly in midweek, winning 2-1.