Help with a current source/sink circuit

[johnkaz77]

Hi,i have this circuit that sources current when Vin+ and sinks when Vin-, however i don't really understand how it works,can anyone explain?Moreover I should control Vin- and Vin+ with a pot with its 2 edges connected to negative and positive power supply respectivelly,how can this be done?If the 2 inputs of the op amp are the same how will it work??Am i missing something here?

 

[Roff]

See my reply in the All About Circuits forum.