However, there is a datasheet for the JW1981, which is a linear LED driver. After reverse-engineering the PCB, [bigclivedotcom] concluded that the JWB1981 must include an onboard bridge rectifier.

comprise a transformer, rectifier, and filter capacitor. Many single-voltage power suppliesconsist of a transformer, arectifier, and a filter capacitor, as shownin Figure 1. This circuit is ...

Power supply section consists of a 0-18 volt AC 1 Ampere step-down transformer, a full wave bridge rectifier ... The LED act as the charging status indicator. LED lights only if the battery is ...