Why do some led work lights make hissing sound after they are connected to power supply

Sometimes, a led work light might make hissing or buzzing sound and flash a little after it is connected to regulator power supply, which usually arises from internal electronic vibration inside LED driver ic that regulates the electrical current flowing to the LED chips.

Basically, the LED driver ic may struggle to regulate the current and cause the components inside to vibrate and cause noises after the power load of LED work lamp is too high or the input voltage is fluctuating.Sometimes, unstable power supply may arise from loose wiring. The electricity will have intermittent contact that results in buzzing and hissing sound.When a LED work light is connected to a optional dimmer switch , it can make the led driver ic have an uneven current flow. Some traditional dimmer switches work differently from bespoke ones, their incompatibility might make some unexpected troubles. If EMI components are installed onto PCBAs, the abnormal frequency interference can lead to electrical oscillations arising from improperly wound coils or a lack of proper insulation like epoxy on the inside components.

Adjust the input voltage might stop the hissing sound for the time being, but the potential problem is still there. To solve this problem completely, a new pcba must be designed and pass the relevant tests, which can withstand rated power supply and avert the possible fire hazard in the end.