Ah, that makes sense. I hadn't thought about the drive being a current source. In that case the anode follower I posted would not make sense. Better to use FB to the cathode in that case I think but I am not well versed in I-V converters so I best bow out, watch and learn. ![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)