Basics of Electronic Circuits (2) - Use of Multimeter

1. Use of multimeter

A multimeter is a magnetoelectric instrument with a rectifier that can measure multiple electrical parameters such as AC and DC current, voltage, and resistance. For each electrical quantity, there are generally several ranges. It is also called a multimeter or simply a multimeter.

It is commonly used in short circuit detection, product quality inspection, and measurement of voltage and current in circuits.

The red test lead interface represents the signal input end, and the black one is the common end.

Measurement Guidelines:

1. Place the multimeter horizontally (the multimeter in this article is a digital multimeter, and its bracket is opened and placed at the back).

2. Confirm that the pointer points to 0 (for pointer multimeter, not relevant to the multimeter in this article).

3. The red test lead interface represents the signal input end (red socket on the meter), and the black test lead is connected to the common end (black socket on the meter).

4. Select the range (if you don’t know the specific value of the device to be tested, start with the largest range and then change the range downwards in sequence).

5. The gear cannot be changed during measurement.

1.1 Construction of a multimeter (measuring resistance)

The internal structure of the digital multimeter (used in this article) is as follows:

The red test lead applies positive voltage and the black test lead applies negative voltage.

The internal structure of the pointer multimeter is as follows:

The red test lead applies negative voltage and the black test lead applies positive voltage.

Used to determine whether a transistor is PNP or NPN, determine the positive and negative poles of a diode, determine whether a field effect transistor is P channel or N channel, etc.

1.2 Circuit continuity detection

First test the multimeter's own ability to detect on/off circuits.

Detection circuit

1.3 DC voltage measurement

The red test lead is connected to the positive terminal (+), and the black test lead is connected to the negative terminal (-).

Reverse connection measures negative electricity.

1.4 Measurement of DC Current

Connect the multimeter in series with the load. (Pay attention to the measuring range, and don't burn it out).

The concatenation method is as follows:

Actual circuit break.

The red test lead is the input terminal, which is connected to the positive disconnection point of the actual circuit. The black test lead is the output terminal, which is connected to the negative disconnection point of the actual circuit.