Understand the polarity discrimination method of rectifier bridges

Understand the polarity discrimination method of rectifier bridges

Before measuring a rectifier bridge, it is necessary to identify the polarity of the interfaces of the rectifier bridge.

Most rectifier bridges are marked with "+", "one", and "~" symbols (where "+" is the positive pole of the rectified output voltage, "one" is the negative pole of the output voltage, and two "~" are the AC voltage inputs), and it is easy to determine each electrode.

Individual rectifier bridge labels cannot be identified for some reason, but they can be identified in the following two ways:

1. Appearance discrimination method

The full bridge consists of four diodes with four pins. The connection point of the negative pole of the two diodes is the "positive pole" of the full-bridge DC output, and the connection point of the positive pole of the two diodes is the "negative pole" of the full-bridge DC output. Most rectifier bridges are marked with "+", "-", "~" symbols. (where "+" is the positive terminal of the rectified output voltage, "-" is the negative terminal of the output voltage, and "~" is the AC voltage input), it is easy to determine each electrode.

2. Multimeter detection method

If the positive and negative polarity markings of a component are blurred, they can also be detected with a multimeter. When testing, the multimeter is set to "R×1k" block, the black meter pen is connected to a pin of the full-bridge component, and the remaining three pins are measured with the red pen, if the measured resistance value is infinity, the pin connected to the black meter pen is the DC output positive pole of the full-bridge component; If the measured resistance values are in the range of 4~l0kΩ, the pins connected to the black meter at this time are the DC output negative pole of the full-bridge component, and the remaining two pins are the AC input pins of the full-bridge component.