A bridge rectifier typically outputs positive voltages only. It rectifies an AC input into pulsating DC where the voltage swings between zero and the peak value of the AC input voltage. The output voltage waveform consists of only positive half-cycles. Therefore, by itself, a bridge rectifier cannot directly generate negative voltages.
To generate negative values using a bridge rectifier, additional circuitry is required. One common method is to use a center-tapped transformer along with the bridge rectifier. By connecting the center tap of the transformer to ground and using the two ends of the secondary winding with the bridge rectifier, it becomes possible to obtain both positive and negative voltages relative to the center tap. This configuration is known as a center-tapped full-wave rectifier.
In a bridge rectifier, the terms positive and negative refer to the polarity of the DC output relative to the ground or common reference point. The positive terminal of the bridge rectifier output will have a higher potential relative to the negative terminal when measured with respect to ground.
Bridge rectifiers have several limitations. One significant limitation is that they cannot handle very high voltages or currents compared to other rectifier configurations. Additionally, the voltage drop across the diodes in the bridge introduces a small loss in efficiency. Moreover, they are typically used for low to moderate power applications and may require heat sinking for higher power levels.
A full-wave rectifier, including a bridge rectifier, rectifies both halves of the AC input cycle into DC. The term “full-wave” implies that the rectifier uses both the positive and negative half-cycles of the AC input waveform. However, the output of a full-wave rectifier, including a bridge rectifier, is positive DC voltage. To obtain negative DC voltage, additional circuitry such as an inverter or a negative voltage regulator is needed.