Create a touch sensor-controlled LED lamp with dimming and rechargeable features. This guide provides step-by-step instructions for building it yourself, using easily accessible components.
LED drivers are classified by output regulation into constant current, constant voltage, and constant power types. Constant current drivers keep a fixed current to stabilize brightness in series-connected LEDs, while constant voltage drivers suit parallel LED modules but incur energy losses through resistors. Constant power drivers adjust the current to maintain steady power, offering flexibility with LED suppliers, though at a higher cost.
Let's assemble a completely analog PWM LED brightness controller using four operational amplifiers and figure out why PWM is needed and what it is.
LED fixtures need drivers to convert AC to DC, lower voltage, and stabilize current. Drivers can enable dimming. They can be 40–50% of fixture cost. While LEDs last up to 100,000 hours, drivers last ~50,000 due to aging capacitors. High-end drivers use film caps but cost more. Focus on driver warranty for a better gauge of overall fixture longevity.
Using a 74LS90 and resistor DAC, the circuit outputs stepped voltages for LED brightness. An op amp amplifies them, providing incremental LED current. Simple dividers and counters manage timing, while a flip-flop and 555 monostable enable manual or automatic stepping. This low-cost approach demonstrates basic LED dimming with minimal components.
