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 NXP Semiconductors

  • Solar Garden Light with Programmable Timer Circuit

  • Created: Nov 17, 2014

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This project uses solar panel with programmable timer controller to energize or de-energize the LEDs as desired by the user. It uses 74HC4060D binary counter, a high-speed Si-gate CMOS device that has 14-stage ripple-carry counter/dividers with oscillators that have three oscillator terminals (RS, RTC and CTC). In addition, it has ten buffered outputs (Q3 to Q9 and Q11 to Q13) and an overriding asynchronous master reset (MR).

Solar garden light with programmable timer is a 74HC4060D binary counter interlinked together to form a set of sequential programmable timers. During day time, when the solar panel is active, the connected battery is allowed to charge through it, while the 74HC4060D timers are held inactive due to the presence of the positive voltage from the panel to pin12 of U1. When darkness sets in, the voltage is brought down to zero allowing pin12 to get a resetting zero logic via the connected 1MΩ resistor. U1 begins counting and after a predetermined delay set by pin 9, capacitor and pin 10 with potentiometer, its pin3 goes high. The BC547 connected with this pin3 now activates all the connected LEDs illuminating them after the desired period of time has elapsed. The 1N4148 diode connected across this pin3 and pin 11 of the U1 freezes the IC counting process and latches the LEDs permanently ON. However, in this situation, the lower BC547 also gets triggered and resets pin12 of U2. Then, U2 begins counting and identically after a set period of time, its pin3 will be on a high state. When pin3 of U2 is high, it latches itself due to the presence of the 1N4148 diode across its pin3 and pin 11. Furthermore, it grounds the base of the LED BC547 driver such that all LEDs will be shut off.

The portable solar garden light is energy efficient since it only requires a solar energy to drive the circuit. This device can be used for commercial applications whatever may be preferred by the user. It can be installed in restaurants, hotels or houses that have gardens which effectively saves energy and money. It can also operate as lamp post during industrial activities, military activities and can be installed in roadways.