Dilshan R Jayakody’s Web Log

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,...

When comes to electronic designing and testing, adjustable current sources facilitates to simulate "load" on the circuit(s). The most common use of "constant current source" is to test the performance of power supply units and battery packs. The current source introduced in this article is capable to handle current up to 6A with a maximum input voltage of 50V. This is an operational amplifier based adjustable current source and it uses LM358 in a general voltage follower configuration. To handle large currents we use four 0.1Ω 20W resistors as "load resistor", and those load resistors are drive through pair of 55N06 N-channel MOSFET transistors. Final view of adjustable constant current source prototype. The power supply unit of this project is built around 9V × 2 (2A) step-down transformer and it is designed to get regulated 12V DC voltage. In our design, this 12V power source is used to drive LM358 Op-Amp and 12V cooling fan. In our PCB desig...