This is a more general stuff, thus I start a new thread, if I may.
One of the thoughts was to be able to support up to 10 mA output current without major problems.
with 10 mA I would think about 4 Wire output.
with best regards
Andreas
This is a quick and dirty idea how to make 4W out of the current "2W standard design". It requires negative voltage and 2 additional opamps, that is a complication, indeed, but it works fine 4W or 2W. The major issues I still see are:
1. the inverter's gain should be the same as the 7->10V ratio divider,
2. the zener's bias changes a little bit with the amount of the drop on the cables.
Perhaps it could be done differently, simpler??
PS: the 4W/2W leads are 1m long 0.3mm dia copper wires..
The non-inverting input of the U7 should go directly to the STAR2 point, to be precise..