Figure is a high output voltage current conversion circuit . This circuit uses the floating of the soil 15V and the +250 V power supply , you can get more than 2OOV load voltage. Input voltage U; to 0 a -lOV, is R1 and R2 partial pressure after the a 0 of a -lV. It is assumed that Al inverting input voltage of -lV, to ground potential as a benchmark , the Al output placed in a positive , VTl a base current flows , so the output voltage increases, current f. = lV/R3 flows through the load. When I. R3 =- lV , the loop is stable, if R3 in the of 0.1 a lOkO range of variation , you can convert lOmA a l0OµA current. If the maximum output voltage U. To 2OOV, and current lOmA, lmA and 100µA of the maximum load resistance are 2OkO, 2OOkO and 2MO.