USB 20W COB LED Table Lamp

The USB 20W COB LED Table Lamp operates by taking a standard 5V supply from a USB breakout board and using an XL6009 DC-DC converter/booster module to step up the voltage to the level required by the high-power COB LED. To control the brightness of the lamp, a 555 Timer IC is configured in an astable circuit to generate a pulse-width modulation (PWM) signal. The frequency and duty cycle of this signal are adjusted using a 470k ohm potentiometer, allowing smooth dimming control. Because the 555 timer cannot directly drive a high-current 20W load on its own, the PWM control signal is fed into a TIP32C power transistor, which acts as an electronic switch. Signal diodes (D1 and D2) are used within the timing network to shape the switching behavior. As the transistor rapidly switches the current flowing through the COB LED on and off based on the PWM duty cycle, the perceived brightness of the lamp changes without wasting excessive energy as heat. Proper thermal management via a suitable heat-sink is essential for both the TIP32C transistor and the COB LED to ensure reliable, long-term operation under continuous power loads.