Description
Setup a green wire from the factories to the input of the Selector Combinator set to read stack size. Factories set to read ingredients. The arithmetic combinator multiples the stack size by 10 or more if you want to. that output goes into radar.
the bottom decider is then wired to the arm and works out supply vs demand, make sure you read all belts as a red wire into the input of the decider. arm is set to activate when B = 1 which means demand is more than supply.