How to use the diode range of a multimeter
Use the diode mode of the digital multimeter, insert the red test lead into the VΩ hole and insert the black test lead into the COM hole. We know that in the digital multimeter, the red test lead contacts the positive electrode of the internal battery, and the black test lead contacts the negative electrode of the internal battery. In the analog multimeter, the electrical barrier is that the red test lead contacts the internal battery. Battery negative black test lead contact
For the positive terminal of the internal battery, touch the red test lead of the digital multimeter to the positive terminal of the diode, and the black test lead to the negative terminal of the diode. (Measure the forward resistance value) The normal value is 300-600Ω
Then touch the red test lead to the negative electrode of the diode and the black test lead to the positive electrode of the diode (to measure the reverse resistance value). The normal value is "1". If both measurements show 001 or 000 and the buzzer sounds, it means that the diode has broken down. If If the forward and reverse resistance values of the two measurements are both "1", it means that the diode is open circuit. If the two measurement values are similar, it means that the quality of the tube is very poor. The reverse resistance value must be "1" or more than 1000, and the forward resistance value must be 300. -600Ω. Then the diode is good.
Diode, (English: Diode), among electronic components, is a device with two electrodes that only allows current to flow in one direction. Many uses are to apply its rectifying function. The variable capacitance diode (Varicap
Diode) is used as an electronic adjustable capacitor. The current directionality possessed by most diodes is usually called the "rectifying" function. The most common function of a diode is to only allow current to pass in one direction (called forward bias) and block it in the reverse direction.
(called reverse bias). Therefore, a diode can be thought of as an electronic version of a check valve.
1. Digital multimeter: Set the gear to the Ω position, connect the red test lead to the anode of the diode, and the black test lead to the cathode of the diode. The meter shows a path (with a certain resistance value); conversely, connect the black test lead to the anode of the diode and the red test lead. Connect the cathode of the diode. If the meter shows an open circuit (the resistance is very large), it means the diode is good.
2. Mechanical multimeter: Set the gear to the Ω position, connect the black test lead to the anode of the diode, and the red test lead to the cathode of the diode. The meter head shows a path (with a certain resistance value); conversely, connect the red test lead to the anode of the diode and the black test lead. Connect the cathode of the diode. If the meter shows an open circuit (the resistance is very large), it means the diode is good.
3. The red test lead of a digital multimeter is connected to the positive terminal of the battery in the meter, while the opposite is true for a mechanical multimeter, so you must correctly distinguish between the red and black test leads before measuring.
4. During the measurement, if both the forward and reverse directions show a path, or both show an open circuit, it means that the diode has been damaged.
