US Patent 7098648 Automatic range finder for electric current testing

In an electrical circuit for testing electrical current using a plurality of precision resistors connected in parallel or in series, a range finder for receiving the current to be measured with the voltage drop across the range finder being indicative of a current sub-range for measurement. In a preferred embodiment, a range finder has a first bipolar transistor and a second bipolar transistor connected in parallel and in opposite polarity with the emitter and base of each transistor connected together whereby each transistor functions as an emitter-base diode.