Showing posts with label multiple. Show all posts
Showing posts with label multiple. Show all posts

Multiple Applications of High Power LEDs

Friday, September 19, 2014 | Labels: , , , , , | 0 comments |
Nowadays, high-power light-emitting diodes (LEDs) LXHLMW1C are available in the market. These white LEDs contain indium-gallium-nitrogen (InGaN). The LEDs’ emitting capacity is 20 candela (Cd). We can use these LEDs for automatic garden lighting and wide voltage operation by applying different voltages.

Multiple Applications of High-Power LEDs


Fig. 1: Circuit for automatic garden lighting

Fig. 1 shows the circuit for automatic garden lighting. Switch S1 connects 12V to the circuit built around transistors T1 and T2. Light-dependent resistor LDR1 is used to sense the light intensity and preset VR1 is used to adjust the threshold of light. The resistance of LDR remains low in daylight and high at night (in darkness).

In the morning, light falls on LDR1 and transistors T1 and T2 are cut-off. As a result, 12V supply is not available to the LEDs. In the evening, when no light falls on LDR1, transistors T1 and T2 conduct to provide 12V to the LEDs. This turns on all the LEDs (LED1 through LED60). The on/off switching level can be adjusted by 220 kilo-ohm preset according to the intensity of the light.

The emitting capacity of LEDs (UW-510CWH) used here is 8 Cd. Since a total of 60 of these LEDs have been used, this unit will provide luminous intensity equivalent of 480 Cd. The LEDs are arranged in twenty rows, with each row having three LEDs in series. The input voltage is approximately 12V and all the LEDs are spaced 1 to 1.5 cm apart.

Fig. 2: Circuit for wide-voltage operation

The entire circuit, except LDR1, can be assembled on any general-purpose PCB. House the PCB in a box and, using two long wires, mount LDR1 at a place where light falls on it directly. Now place the unit in your garden.

You can use the switching section for other systems as well. You just need to remove the LED section from the circuit and connect the switching section to the desired system. So the system will now automatically switch on in the evening and switch off in the morning.

Fig. 3: Pin configuration

Fig. 2 shows a wide-voltage operation circuit. Here, the high-power LED61 (LXHLMW1C) gives a power equivalent of 20 Cd. This LED has a metallic back for mounting on a heat-sink. Its rated maximum input DC voltage and current are 3.6V and 350 mA, respectively. Regulator IC LM317 (IC1) provides a constant voltage of 4.7V. Resistors R3 and R4 limit the current through the LED. The LED is very sensitive to voltage inputs. In the 2.5V-3.5V region, each millivolt variation changes the current through the LED logarithmically. Transistors BC549 and D882 (T3 and T4) and resistor R6 provide a constant current to LED61. The unit gives a constant lighting for voltages ranging from 7V to 25V.

Fig. 3 shows pin configuration of regulator LM317 and transistors D882 and BC549. Use heat-sinks in regulator LM317 and transistor D882 before soldering them onto the PCB.
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SP How to Make an AVR Perform Multiple Tasks

Wednesday, May 29, 2013 | Labels: , , , , , , , , | 0 comments |
This article describes a way to create an AVR perform multiple tasks. Beginners who want to urge an in-depth information in AVR assemble language programming will seek this project. The assembly language helps to utilize all the functions and capabilities of the processor. browse on to grasp a lot of.



The most vital and major functionality of an operating system is performing multiple tasks on the CPU. whats being done here is time sharing multitasking which too on an AVR. An Atmega32 is ready up to perform Round-Robin Multitasking. Quasi-parallel execution of multiple tasks is feasible through Round-Robin Multitasking. The tasks are time-sliced and dont seem to be tired parallel.

The project demonstrates how the switching mechanism is finished between seven individual tasks. The RAM is split between the amount of processes that are running. A timer is employed here and a trigger is executed when it reaches a compare worth. the required registers are pushed onto the stack.

Now comes the method of switching between the varied tasks. A backup of the present stack pointer is needed as this helps to spot the previous task that was being executed. concerning fifty bytes of memory is formed offered to store the task index. this is often the stack pointer backup table.