Dilshan R Jayakody’s Web Log

The main objective of this project is to design a maintenance free and low-cost light which automatically turns on and off at the predetermined time of the day. To meet the above requirement I designed this controller using ATmega8 MCU and DS1307 RTC. The driver stage of this light controller is intended to work with commonly available 7W LED modules. PCB of the programmable light controller. The core component of this programmable light is ATmega8 low power CMOS microcontroller. The main reason to select this microcontroller is it’s lower cost and higher availability. Except for the above two reasons this microcontroller also bundled with a rich set of peripherals which including 23 GPIOs, 3 independent timers, Two-wire serial interface, EEPROM, etc. Apart from ATmega8 microcontroller, this system uses DS1307 real time clock to maintain system time. Like ATmega8, DS1307 is also a very popular RTC in the market. This controller is designed to work with a 24V DC power supp...

This is a real-time clock based automatic LED lamp which we originally designed to use as a night light. This lamp can be programmed to turn on and off at the specific time of the day. For example, it can program to turn on at 6 PM on each day and to turn off at 4 AM the next day. The core component of this project is PIC16F883 MCU and its firmware is developed using MikroC Pro for PIC . We select this MCU because of its 7 KB flash memory, I 2 C, UART, E 2 PROM and built-in 8-bit and 16-bit timers. In this system, we use DS1307 RTC because of its availability in the market and lower external component count. A prototype version of RTC Lamp This lamp is designed to work with commonly available 7W LED panels. In our prototype design, we use 7W 24V warm-white LED module to test this system. To drive other LED modules change the value of the R5 resistor of the current limiter circuit. This system is designed to program using the RS232 serial port. A user can modify system time,...

AN6877 is linear AF level meter IC produced by Panasonic and it is commonly found on much audio equipment. This chip is no longer manufactured by Panasonic and finding replacement chip for AN6877 is also quite difficult. The circuit described in this article is designed to replace AN6877 base LED drivers and it is based on commonly available components. This replacement LED driver is designed using 10, MMBT3904/2N3904 transistors and it can easily modify to get the necessary number of outputs. During the prototyping stages, we test this driver with a minimum of 7 LEDs (AN6877 configuration) and up to 12 LEDs. This LED driver is designed to work with 9V to 12V DC power source. With 7 LEDs and 9V power source, this module can directly replace AN6877 base LED driver modules. Schematic and PCB design related to this LED driver is available at google drive .

This is simple telephone locator-light which is used to identify the ringing telephone at the night / low light conditions. This unit only activates at low light conditions and it automatically turns off lights after 12 - 15 sec. from the last ring. This telephone locator is mainly based on NE555 timer IC and it is designed to work with 6V 0.5A - 1A power source. This given schematic support a maximum of two 3W power LEDs. During the assembly, it is important to place both LEDs and LDR in two separate positions to avoid any interference to LDR from LEDs. Also, note that in some counties it is illegal to connect custom circuitry into phone lines, please check your local regulatory bodies is concerned. Schematic and PCB designs of this unit are available to download at google drive .

This is quick post about 3W constant current LED driver which I was design to combine with some homemade furniture piece. The main components of this system is LM311 voltage comparator and IRF9 5 40 P-Channel MOSFET. Schematic of 3W LED driver module This module is design to drive maximum of two 3W high power LEDs and it requires 8V - 10V DC (500mA) power source. In this given configuration this module may not need any heat-sink (for IRF9540) and consume maximum of 500mA of power. Breadboard version of 3W LED driver At prototyping stages we test this module using 9V DC (1A) power supply with two 3W LEDs (EDEX-3LA1-E1). I developed final version of this module using piece of strip-board and PCB design is not done.