Abstract: A zero flux error transductor for the DC power supply with high current stability is developed. The principle is analyzed. The transductor consists of four separate magnetic cores with perm ribbon. As a feed back component the transductor has the following advantages: a small volume and weight (<200 g), power loss≤1 W, low cost, small temperature coefficients. The current stability of the power supply at 40 A is ≤1×10 -4 for 24 h.