Voltage measuring circuit

摘要

The invention relates to a voltage measuring circuit, especially for measuring the output voltage of a switched-mode power supply. According to the invention a first switching transistor (TR2) periodically switches the output voltage to a primary winding (W4) of a measuring transformer (T2). The induced secondary voltage of the transformer (T2) is rectified and switched to a control circuit by a second switching transistor (TR3). The first and second transistors are synchronized and exhibit a resistive voltage/current behaviour in a conducting state.