LED Heart PWM Fading

The concept for this small birthday present was to create a small heart shape with red LEDs and then to draw a heart shape underneath it on the PCB as a backdrop. Then a small processor was added to control the heart shape of LEDs for both fade and pattern control. The method of control that we use (PWM) allows us to save precious battery life, control the exact brightness of each specific LED and create this tiny but awesome project. [Link]

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Simple High Power Triac Dimmable LED Driver

A 20 Watt Triac dimmable LED driver. This is basically a current controlled step-down switching power supply. The circuit is powered directly from mains so be careful with this one.

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Remote Solar LED Light

I created this circuit in an attempt to make the simplest possible solar powered project. It would make for an excellent science fair project, and would also serve as a good introduction to solar powered circuitry. It may also have some practical uses, such as shedding some light into a dark part of your house. The idea is simple, the solar panel converts sunlight into a trickle of electricity. The electricity is used to run a white LED.

 Remote Solar LED Light  Circuit Diagram

Specifications:

• Operating Voltage: 3.7V DC
• Solar Current: 25ma max.
• LED Lamp Operating Current: 10-25ma.

Theory:
The remote solar powered LED light takes advantage of the current limited nature of solar photovoltaic cells. If light shines on the solar array, current will flow through the circuit. For a typical size of solar cell, there is a maximum current that can be produced. The maximum solar cell current is simply matched to a value of current that the LED can handle. If there is enough light to raise the solar panels voltage above around 3.7V, the white LED will light up. The LED regulates the maximum voltage across the circuit to around 3.7V.If the solar panel that you use produces more than 20ma, it may be necessary to insert a series resistor between the LED and the solar panel to prevent the LED from burning out.

A 50 ohm 1/4 watt resistor is probably about right for the job, the exact value may need to be optimized according to the solar panel that you use.This concept could easily be expanded to systems with larger arrays of solar cells and more LEDs. The capacitor is not required, but it will keep the LED from flickering if the panel is briefly blocked, such as when a bird flies by. With 7 solar cells, the LED will only light in fairly bright light, if you use up to 10 solar cells, the circuit will work nicely in overcast skies.For an interesting modification to this circuit, replace the 1000uF capacitor with a 1 Farad/5.5V "Memory Backup Capacitor". An Elna DB-545D105 device was tested on the circuit, after charging up in the sun for a few minutes, the capacitor was able to light the LED for several minutes.

Construction:
Most of the work goes into making the solar panel. Lay out the cells in any pattern. Cut the two pieces of plexiglass and one piece of perforated circuit board so that they are wider than the solar array. Stack the three board layers together and drill holes for the mounting screws. When the project is finished, the center circuit board will be spaced away from the front and back plastic panels with extra nuts acting as spacers on the mounting screws. The idea is to get an air gap above and below the circuit board so that there is room for the solar cells and wiring.

Mount the solar cells on the perf board and solder them into a series string. An easy way to do this is to connect short segments of bare wire-wrap wire to each cell, route the wires through the perf board and solder the ends on the bottom. Connect two wires to the ends of the series string of cells and secure the wires to the circuit board. For outdoor applications, seal the edge of the panel with silicone caulk or other water proof material. Also, seal the mounting screws where they pass through the plexiglass.Connect the LED and capacitor in parallel, wire them across the two power leads. Be sure to get the polarity correct, otherwise the LED wont light up. Solder the parts together. Be sure to heat-sink the LED leads while soldering, LEDs can be easily destroyed with too much heat.

Use:
Place the solar panel in the sun, the LED will light. The photo at the top of this page shows the circuit operating indoors on a cloudy day. If you put the LED on a long wire, it can be placed in a dark location, such as a corner of your basement. As long as there is a fair amount of light in the sky, the LED will light up. To get the best orientation for the panel, aim it directly at the sun at noon during March or September.

Parts:
7-10x photovoltaic cells, rated at 15-25ma each.
1x white LED, high efficiency types work best.
1x 1000uF 15V (or greater) electrolytic capacitor.
1 piece of perforated or printed circuit board.
2 pieces of clear plexiglass.
28 gauge bare wire-wrap wire.
24 gauge speaker wire.
miscellaneous screws, nuts, and washers.
silicone caulk.

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Reuse Old Mobile Phone Battery for LED lighting

Normally mobile batteries have a lifespan of 2-5 years under normal usage. But then we have to replace them. Nowadays there are cheap replacement batteries which cost no more than 1$. But these low cost batteries run only 6-12 months. What to do with the used batteries, which can’t be reused in mobiles? Well, easy solution is to use the batteries in a circuit that requires less current. We can use them for LED lighting.

Do you have old unusable Mobile battery?

Normally mobile batteries have a lifespan of 2-5 years under normal usage. But then we have to replace them. Nowadays there are cheap replacement batteries which cost no more than 1$. But these low cost batteries run only 6-12 months. What to do with the used batteries, which can’t be reused in mobiles?

Well, easy solution is to use the batteries in a circuit that requires less current. We can use them for LED lighting. Thus your automatic lighting emergency light is ready which runs by your waste Mobile Battery.

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Blinking LED Circuit Diagram

This is a blinking LED circuit diagram.Here I have used common IC NE555.If you want to change the speed of this circuit you can change the value of R2.Then you can do that.


Note

* Use a PCB to build this circuit
* You can operate this circuit with 9V

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10 Channel LED Sequencer

this is how to Build 10 Channel LED Sequencer may you have another idea, will be good if you share here.

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LED Camera

The process mentioned below shows how we can convert the LEDs to the light sensors so that it can be used for many other purposes also. Read on to know more about this.As the Blinkenlight Shield has 20 of them, 20 pixel camera can be developed by it. After performing the experiment, it is recommended to reset the jumper setting to default. LED or Light Emitting diodes usually act as the photo diodes and are optimized to produce the light.

LEDs can be used to make the light detectors that can be helpful in various conditions. The idea behind this is to reverse bias the diodes by turning the IO pins to output low so that the LEDs used will act as capacitors and will not be conducted. The current produced due to the LED is very small, and the photo current produced discharges the LED capacitors. After charging, the IO pins have to be switched to high Z so as to generate the light. The light produced and the current are directly proportional to each other.

After the discharging of capacitors, the pin will move towards high from low. By measuring the time taken for discharge, the amount of light reached by the LED can be calculated. After processing all the LEDs, they can be used in a serial line but it should be taken care of that this is done in a separate step to avoid any mistake in measuring the discharge time.

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Flashing LED Battery status Indicator

Signals when an on-circuit battery is exhausted 5V to 12V working voltage

A Battery-status Indicator circuit will also be useful, mainly to observe portable Test-gear units and equivalent devices. LED D1 flashes to apparel the customers attention, signaling that the circuit is operating, so it's going to no longer be left on by using mistake. The circuit generates about two LED flashes per second, however the mean present drawing might be about 200µA. Transistors Q1 and Q2 are wired as an unusual complementary astable multivibrator: each are off 99% of the time, saturating best when the LED illuminates, in this case contributing to keep very low current consumption. 

Circuit diagram :

Flashing-LED Battery-status Indicator Circuit Diagram

The circuit will work with battery supply voltages within the 5 - 12V vary and the LED flashing will additionally be stopped at the desired battery voltage (comprised within the four.8 - 9V worth) by way of adjusting Trimmer R4. This vary can also be modified via altering R3 and/or R4 worth relatively.

When the battery voltage methods the onerous price, the LED flashing frequency will fall suddenly to alert the consumer. Obviously, when the battery voltage has fallen under this price, the LED will stay completely off. To maintain steady the exhausting voltage price, diode D1 was once brought to compensate Q1 Base-Emitter junction changes in temperature. The use of a Schottky-barrier device (e.g. BAT46, 1N5819 and the like) for D1 is mandatory: the circuit is no longer going to work if a common silicon diode just like the 1N4148 is used as an alternative.

Parts :

R1,R7__________220R  1/4W Resistors
R2_____________120K  1/4W Resistor
R3_______________5K6 1/4W Resistor
R4_______________5K  1/2W Trimmer Cermet or Carbon
R5______________33K  1/4W Resistor
R6_____________680K  1/4W Resistor
R8_____________100K  1/4W Resistor
R9_____________180R  1/4W Resistor
C1,C2____________4µ7  25V Electrolytic Capacitors
D1____________BAT46  100V 150mA Schottky-barrier Diode
D2______________LED  Red 5mm.
Q1____________BC547   four5V 100mA NPN Transistor
Q2____________BC557   45V 100mA PNP Transistor
B1_______________5V to 12V Battery provide
Notes :

• Mean current drawing of the circuit can be lowered further on by using elevating R1, R7 and R9 prices.

Source : Red Circuits

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LED DETECTS lightweight

All LEDs offer off lightweight of a specific color however some LEDs also are able to detect lightweight. clearly theyre not nearly as good as a tool that has been specially created to detect light; like solar cell, photocell, photo resistor, lightweight dependent resistor, photo transistor, photo diode and different photo sensitive devices.

A inexperienced LED can detect lightweight and a high-bright red LED can respond about a hundred times higher than a inexperienced LED, however the LED during this position in the circuit is classed as terribly high impedance and it needs a considerable quantity of amplification to show the detection into a worthwhile current-source. All different LEDs respond terribly poorly and arent price making an attempt. The accompanying circuit amplifies the output of the LED and permits it to be used for variety of applications.
The LED solely responds when the sunshine enters the tip of the LED and this makes it ideal for solar rackers and any time theres an outsized difference between the dark and light-weight conditions. itll not detect the
light in a very area unless the lamp is incredibly shut.

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How to Make a Simplest Compact 1 Watt LED Driver Circuit at 220V 110V Mains Voltage

Circuit diagram.

Seetharaman’s words about the circuit: I am sending you a table lamp made from defunct energy saver lamp with broken tubes. CFL converted into LED lamp. Most of the components will be available in ones scrap box. Few components available in the CFL PCB also can be used.

Procedure
1. Carefully remove the broken glasses
2. Open the assembly carefully
3. Remove electronics and discard
4. Assemble the circuit in dot matrix PC or on a 1mm laminate sheet.
5. Cut a round laminate sheet with (scissor)
6. Mark the position of the 6 round holes on the sheet
7. Drill the holes to suit the LEDs to flush fit in the six holes
8. Use a dab of adhesive to keep the LED assembly in position
9. Close the assembly
10. Ensure the internal wiring does not touch each other
11. Now test on 230Volt AC
Your nice compact table lamp / puja room lamp / passage lamp is ready for use.

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