Patent ID: 8829891
Filing Date: 2014-09-09
Classification: G01R

Abstract:
1. A digital multimeter comprising: a single chip processor a sound chip connected to the single chip processor; a signal amplifying circuit; a speaker connected to the signal amplifying circuit; a battery for providing electrical energy for the digital multimeter; and an interface for connecting a microphone, the interface connected to the sound chip; wherein a first capacitor, a first resistor and a second capacitor are connected in series between a first pin of the sound chip and ground, a third capacitor, a second resistor and a fourth capacitor being connected in series between a second pin of the sound chip and ground, a first port being formed between the first resistor and the second capacitor, a second port being formed between the second resistor and the fourth capacitor, the first port and the second port cooperatively forming the interface for connecting a microphone, one end of a third resistor being connected to the first port, one end of the fourth resistor being connected to the second port, the other ends of the third and fourth resistors being connected to two cathodes of two diodes, two anodes of the diodes being connected to a first direct current power source; wherein the single chip processor collects high and low level signals of measurement values of the digital multimeter, and converts the high and low level signals into codes which the sound chip can recognize, and transmits the codes to the sound chip; wherein the sound chip converts the codes into audio frequency analog signals and transmits the audio frequency analog signals to the signal amplifying circuit; and wherein the signal amplifying circuit amplifies the audio frequency analog signals and outputs the amplified audio frequency analog signals to the speaker, and the amplified audio frequency analog signals drive the speaker to report the measurement values of the digital multimeter.