Circuits & Schematics - Light

I have modified several commercial solar garden lights over the years. I switch out the LED, solar panel, battery pack and control circuit. The result is a much better overall light. One of my disappointments in using store-bought garden light ...

Applications such as turbidity measurement and densitometry require cleanly pulsed light sources with stable amplitudes. The LED driver in Figure 1 illuminates retinal neurons in a biological experiment that has similar requirements. For a given ...

LEDs need current to illuminate, and current usually flows through a power supply to an LED. A typical LED-driver circuit uses a transistor to provide current and a series resistor to decrease the voltage you apply to the LED. Unfortunately, the ...

The circuit of Figure 1 is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels. The circuit drives as many as four white LEDs from a 3.3 V source and adjusts the total LED current from 1 to ...

Driving LEDs at a regulated current from low supply voltages can be difficult because minimal overhead voltage is available for control circuits. A current-mirror architecture is suitable but usually works only with ICs with well-matched ...

One option for driving high-brightness LEDs uses the standard stepdown buck converter (Figure 1). The sense resistor, R S , generates a feedback voltage, V FB , that sets the desired LED current, I LED , according to the equation Figure 1. A ...

This circuit of only a few components is powered by two AA batteries and features a mode that extends its power savings. Imagine a smart light switch which not only automatically turns itself on when it gets dark, but also adjusts its level of ...

Testing the system Testing was done at various sunlight intensities. For any given sunlight intensity, V PV , I PV , V M , I M , etc., are measured. Figure 5 shows the variation of PV power (P PVON ), converter power (P M ), and total power (P TOT ...

The PV-pushback-effect with solar panels can control backup power and provide constant light output. Solar day lamps (SDLs) are made by simply connecting an LED array to a solar photovoltaic (PV) panel. SDLs represent a highly cost-effective way of ...

Using a blue LED can pose problems when available power-supply voltages don't meet or exceed the LED's 3 V forward-voltage drop. This Design Idea shows how to drive a blue LED from a 3 V battery or another power supply. The circuit in ...