How to detect the remaining battery power with a multimeter?
A multimeter can not only be used to measure the resistance of the object being measured, but also the AC and DC voltages. Some multimeters can even measure the main parameters of transistors and the capacitance of capacitors, etc. Mastering the usage method of a multimeter proficiently is one of the most basic skills in electronic technology. Common multimeters include pointer multimeters and digital multimeters. A pointer multimeter is a multifunctional measuring instrument with a meter head as the core component, and the measured value is read according to the indication of the meter head pointer. The measured value of a digital multimeter is directly displayed in digital form on the liquid crystal display screen, which is convenient to read, and some even have a voice prompt function. A multimeter uses a common meter head and is an instrument that integrates a voltmeter, an ammeter, and an ohmmeter.
The DC current range of a multimeter is a multi-range DC voltmeter. By connecting a closed-circuit voltage dividing resistor in parallel with the meter head, its voltage range can be expanded. The DC voltage range of a multimeter is a multi-range DC voltmeter. By connecting a voltage dividing resistor in series with the meter head, its voltage range can be expanded. Different voltage dividing resistors correspond to different ranges. The meter head of a multimeter is a magnetoelectric measuring mechanism, which can only pass DC. By using a diode to convert AC into DC, the measurement of AC can be realized. The basic principle of a multimeter is to use a sensitive magnetoelectric DC ammeter (microammeter) as the meter head. When a small current passes through the meter head, there will be a current indication. However, the meter head cannot pass a large current. Therefore, some resistors must be connected in parallel and in series with the meter head for current division or voltage reduction, so as to measure the current, voltage, and resistance in the circuit.
The measurement process of a digital multimeter is that the circuit being measured is converted into a DC voltage signal by the conversion circuit. Then, the analog voltage quantity is converted into a digital quantity by the analog-to-digital (A/D) converter. After that, the digital quantity is counted by the electronic counter, and finally, the measurement result is directly displayed on the display screen in digital form.
The functions of measuring voltage, current, and resistance of a multimeter are realized through the conversion circuit part. The measurement of current and resistance is based on the measurement of voltage, that is to say, a digital multimeter is expanded on the basis of a digital DC voltmeter.
The A/D converter of a digital DC voltmeter converts the analog voltage quantity that changes continuously with time into a digital quantity. Then, the digital quantity is counted by the electronic counter to obtain the measurement result, and the measurement result is displayed by the decoding display circuit. The logic control circuit controls the coordinated work of the circuit and completes the entire measurement process in sequence under the action of the clock.
