What Must todo

This is a simple LED flasher project that uses a common 555 timer IC for its operation. It is configured as an astable mode which means that its output is a square wave oscillator. Two LEDs are connected to its output in such a way that when one LED is ON, the other LED will turn OFF. 

It uses only 10 simple parts that are easily available at any electronic shops. Capacitor C2 charges exponentially through resistors R1, R2 and the resistance of the trimpot. When C2 has charged to about 2/3 VCC it stops charging and it discharges to about 1/3 VCC through R2 and the trimpot resistance via pin 7. This is the standard operation of a 555 timer. When a Vcc of 5 V to 15 V DC is applied to the circuit, the LED will start to flash.

The frequency of the flashing can be changed by varying the resistance of the potentiometer or trimpot. Parts List The parts list of the simple LED project is as shown below.

This is a simple circuit. Music can change the LED light level gamut.

Operation of this circuit is a circuit op amp IC1 / 1-IC1 / 5 compared to the characteristics of the circuit voltage.It has one pin acts as a voltage reference pin.That the pressure from the supply voltage and divide between R1 and R7 pressure used in this circuit will be compared with the pressure drop across R7.

Music LED light level

As the 2V input side, it will be R2, R3, R4, R5, R6 series, keeping the pressure drop across.Each R as well.

If there is pressure to 5Vp-p is the voltage across R2 = R3 = R4 = R5 = R6 = 1V.The voltage reference, we have 2V. IC4 circuit compares the measured voltage at the input pin of IC4 is 2V.Which is equal pressure on the leg or legs plus the output of IC4 will not flow to drive the LED light will be more pressure input into this.IC4 to make work. The next LED arranged in the order of the input voltage.
source : http://www.eleccircuit.com/simple-led-light-based-music-using-lm318/

This circuit LED reproduces the first LED sequence at this time used by FISA on behalf of Formula single racing. It may perhaps be alive used with slot car sets (such for example HO shin up AFX/Life Like/Tyco sets) or else means of communication controlled cars. IC1, a 555 timer IC, is used as a watch pulse generator. Its output is fed via NAND gates IC2a and IC2c to IC3, a 4024 binary counter. IC2b inverts the O4 output of 4024 binary counter IC3. originally, IC3 is reset and all its outputs are low, together with O4, which causes IC2b to present-day a rational climax to the pin 8 input of IC2c which after that passes pulses from the 555 timer circuit to the clock input of the 4024. IC3 then begins together with.

Following the count has reached binary 1111, the subsequently pulse sends the O4 output of IC3 high, which disables IC2c and IC3 stops with. The four used outputs of IC3 are connected to a resistor ‘ladder’ which acts to the same degree a clear-cut digital to analog convert-er (DAC). As the count increases so does the voltage produced by the side of the top of the ladder and this is connected to the inverting inputs of four comparators inside IC4 (an LM339) and to IC5, which is a 741 op amp furthermore connected while a comparator.

The categorical inputs of the comparators are connected to the taps of a voltage dividing wall, with the drumming voltages settle on using VR1, a 100kO trimpot. As IC3 counts, the rising stepped voltage from the DAC ladder switches the comparators on clothed in sequence, preliminary with IC4d and working up to IC5. in the same way as both comparator is curved on, its pair off of LEDs is lit; former LEDs 1 & 2, next LEDs 3 & 4 and so on. as soon as all five pairs of LEDs are lit, the then pulse from IC1 moves the binary count of IC3 to 10000, so the DAC voltage drops back to zilch and all LEDs are extinguished. by the same spell, with too stops, for the reason that the area of high pressure on O4 causes IC2c to check extra gate pulses. The circuit in that case remains reserve until the counter is reset by urgent pushbutton switch S1. This allows a recent sequence to initiate.

This arrow led indicator electronic project can be used in some dark places to show the directions . You can use to indicate direction just an illuminated arrow or a flashing light , but is much nicer if the light moves in the correct direction.

This arrow led indicator is based on 74HC14 circuit and some LEDs which are used to show the way .
For this arrow led indicator we need six series of three LEDs arranged in the shape of arrows and are connected to the outputs . Each time the lit arrows move over by one column so it appears that the arrows run from right to left.

Arrow LED Indicator Circuit Diagram



If we want to change the speed of the moving light it’s need to change the value of C1 to C3 or R1 to R3 ( a lower value for this components decrease the time of moving lights). If we want a longer arrow we can mount in parallel with existing columns another columns .
For power supply we can use batteries or 6V regulated power supply .

4) Each column given the constraints, Rx, which amount depends on the number of LEDs in one column and depends also on the type of LED (in this experiment that used LED 5mm in diameter, clear with red light beam).

Remember, this provision applies to 5 mm LED red light beam nodes.

Value Rx in the first and the fifth column (letter A) of 560 ohms, because it consists of 5 LEDs are arranged series. Rx in the second column, third, and fourth, amounting to 680 ohms because it consists of two LEDs.

The LT3754 16 channel LED driver with a step-up DC DC controller designed by Linear Technology is capable of driving up to 45V of LEDs. Each channel of the LT3754 led driver contains an accurate current sink with ±2.8% current matching.If are used high current Leds channels can be paralleled.

16 Channel LED Driver Circuit Diagram

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.

A very simple LED driver electronic project can be designed using the CAT3649 high efficiency quad mode R fractional charge pump IC that can drive up to six LEDs. The inclusion of a 1.33x fractional charge pump mode increases the device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors.Low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. The multi−fractional charge pump supports a wide range of input voltages from 2.4 V to 5.5 V.



The LED current can be adjusted in different ways. The full−scale LED current is set to 25 mA once the device is enabled. Analog dimming in 32 linear steps is achieved via a 1−wire pulse−dimming input (ADIM)
Further adjustment of the LED current can be done by applying a pulse width modulation (PWM) signal on the PWM input.The CAT3649 can be shut down by holding the ADIM or PWM input in a logic low condition for greater than 30 ms. This electronic design CAT3649 charge pump LED driver can be used in applications like : LCD Display Backlight , Cellular Phones , Digital Still Cameras and some other handheld devices .

If the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the CAT3649 automatically switches into 1.33x mode. In 1.33x mode, the output voltage is approximately equal to 1.33 times the input supply voltage . This sequence repeats in the 1.33x and 1.5x mode until the driver enters the 2x mode.While in 2x mode, the output is approximately equal to 2 times the input supply voltage.If the CAT3649 charge pump LED driver detects a sufficient input voltage to drive all LED currents in 1x mode, it will change automatically back to 1x mode.

Lamp type LED has several advantages compared with the usual light when the applied on a motorcycle. In addition to more efficient battery when compared with normal hologen lamps, LED also has several other advantages, such as light more evenly and provide a luxurious feel to the vehicle.

The following are examples of simple creations that you can apply to decorate your motorcycle using the LED.

For this circuit is recommended only as a replacement motorcycle brake lights or city lights with the electrical source from the battery. Indeed in the market has many available variations of LED lights that can be used as brake lights or disco lights, but maybe some people would be proud if his own creative, hopefully circuit schemes that we present above can assist you in creating.

This simple circuit aims to provide an indication of an appliance if it is ON or OFF with the use of green and red LEDs.

• BC337 – a small signal NPN Silicon AF medium power transistor used for general purpose switching and amplifying applications with features such as TO-18 manufactured package, suited for AF driver stages and low power output stages, and divided into three group types.
• Single Pole Single Throw (SPST) – a single on-off switch where the two terminals are either connected together of not connected to anything

The indication produced by the LEDs could mean that the red LED will illustrate that the equipment is turned ON while the green LED will illuminate upon turning OFF the same appliance. It could also be the other way around since green normally signifies that there is life on an equipment. This is applicable with any appliance that is powered and operated by AC mains which can be 230 V or 115 Vac.

A suitable switch SW1 made of single pole single throw type will be capable of handling the full load current. These switches can be in the form of toggle switch, push-to-make switch, push-push switch, tilt switch, reed switch, DIP switch, or push-to-break switch. During the operation, the load and the red diode D4 are being energized when the contacts of switch SW1 is closed. At this stage, the transistor Q1 will get saturated and shorts the green diode D3 which prevents it from illuminating.

Equipment Indicator Using Two LED Schematic



The explanation of the circuit operation pertains to a 230 Vac source. If the source would be coming from 115 Vac mains, the value of R1 and R2 should b3 15K Ohms at 1 W power output. The use of the type of switch SW1 should be able to withstand the full load voltage and current of the equipment.The two LED indicator can are widely used in several equipments and gadgets like the mobile phones. A blackberry phone have a LED indicator that can provide four colors depending on the status of the phone if it is receiving a message or a call, if connected via Wi-Fi, or if connected via Bluetooth. The good thing about the circuit is that it can be used for emergency light indicator, signal light, backup light, dashboard light, or with flash buzzer based on the AD signal light.

DC powered LED lighting circuits can vary from trivial single LED/series resistor combos to simple analog current regulators to more complicated switching power supply circuits such as this project. There is a tradeoff between simplicity and circuit capabilities. This more complex circuit adds features such as regulated light level across a wide range of input voltages and automatic circuit shutoff on low input voltage. By using a high frequency switching regulator, the power loss associated with the current dropping resistors found in simpler circuits is reduced. This offsets the power consumed by the circuits active parts. This circuit can power 10 white LEDs at 24mA of current with only 98mA of input supply current when running on 12V. LED intensity is fully regulated across the entire operating voltage range.

High Efficiency 12V White LED Driver Circuit Diagram



This circuit was inspired by F. Garcias IR LED video illumination circuit, published in the July 2001 edition of Nuts and Volts magazine. I modified the LED count and feedback circuit, and added the important low voltage shutdown feature.

Specifications:

• Power Requirements:
• Operating Voltage: 10-18V DC
• Operating Current: 98mA @ 12V DC (10 LEDs)
• Current at low voltage shutoff point: 5mA

Theory:
The heart of the circuit is a string of 10 white LEDs. These are wired in series and connected to a current-regulated step-up switching power supply circuit.

The LM3578 switching regulator and its associated inductor, 1N5819 schottky diode, and 100uF 50V capacitor step the 12V power supply up to a higher DC voltage. The voltage is approximately 3.7 X the number of LEDs. The 4.7 ohm resistor on the cathode end of the LED string develops a voltage that is proportional to the current through the LEDs. This voltage is amplified by half of the LM358 op-amp and sends a negative feedback signal through a 4.7K resistor back to the LM3578. The 36K feedback resistor across the LM358 sets the LED series current to approximately 24mA. Not all general purpose op-amps will work in this circuit, the LM358 can operate from a single-rail power supply with both input pins near 0V.

The other half of the LM358 (pins 1,2,3) is wired as a 10V voltage comparator. The 1N5231 zener diode and 10K series resistor produces a steady 5V on pin 2 of the LM358. The two 100K resistors on pin 3 of the LM358 divide the input voltage in half. If the supply voltage drops below 10V, the output of the LM358 drops, and pulls pin 2 of the LM3578 down through a 1N5819 schottky diode, causing the LM3578 to shut down. A schottky diode is used instead of a standard silicon diode in order for the LM3578 pin 2 voltage to go low enough to disable the circuit. Without the low voltage shutdown circuit, the LM3578 current will increase as the supply voltage decreases until the IC self-destructs.

The 2.2M resistor across the LM358 produces a hysteresis effect for the low voltage shutoff. The circuit turns off about .25V below where it turns back on, this prevents oscillation around the shutoff threshold. Below the low voltage shutoff point, the circuit will consume about 5mA of current.

An interesting characteristic of this circuit is that it acts as a negative resistance at the power supply terminals. As the supply voltage is increased, the current will drop. The total power consumption stays nearly even across changing input voltage conditions.

Use:
Just connect the circuit to a 12V DC power supply, such as a solar charged lead acid battery. The light level will remain constant through the battery voltage change, and the circuit will consume a minimal amount of power.

It is possible to vary the number of white LEDs in this circuit from 8 to 12, as the LED count goes up, so does the regulators output voltage and input current. Numerous readers have asked me if this circuit can drive more than 12 3.7V white LEDs, 12 white LEDs is about the maximum upper power limit for the LM3578 IC. If you are driving lower voltage LEDs such as 1.4V IR or red parts, the series string can have up to 30 LEDs.

Parts:
1X LM3578AN switch-mode voltage regulator IC
1X LM358P dual op-amp
1X 1N5231 5V zener diode
2X 1N5819 schottky diodes
10X high intensity white LEDs
1X 100uF 25V electrolytic capacitor
1X 100uF 50V electrolytic capacitor
1X 100nF 50V ceramic or MLCC capacitors
1X 2nF 50V ceramic or MLCC capacitor
2X 1nF 50V ceramic or MLCC capacitors
1X 22pF ceramic disc capacitor
1X 0.3 ohm 1/4 W resistor (Substitutes: 3X 1 ohm or 2X 0.62 ohm 1/4W resistors in parallel)
1X 4.7 ohm 1/2W resistor
2X 4.7K 1/4W resistors
1X 10K 1/4W resistor
1X 36K 1/4W resistor
2X 100K 1/4W resistors
1X 220K 1/4W resistor
1X 2.2M 1/4W resistor
1X 1mH 200mA switching power supply inductor
Inductors that are known to work:
Mouser part 851-CDRH74NP-102MC (Sumida SMD)
Digi-Key part TKS3504CT-ND (Toko 875FU-102M=P3)

The TCA62735AFLG is a charge pump type DC DC Converter specially designed for constant current driving of white LED.IC can outputs LED current 120mA or more to 2.8-4.2V input.IC observes the power-supply voltage and the output voltage, and does an automatic change to the best of step up mode 1, 1.5 or 2 times. It is possible to prolong the battery longevity to its maximum.This IC is especially for driving back light white LEDs in LCD of PDA, Cellular Phone, or Handy Terminal Equipment.

Schematic



This electronic project t LED driver is very simple and require few external electronic parts. Due of simplicity of this circuit this project not require additional explanations . If you want to change this design , please consult the manufactured datasheet .Some features of the TCA62735AFLG electronic project are Switching Frequency : 1MHz(Typ.), Output Drive Current Capability : Greater than 120mA , 4 Channels Built in Constant Sink Current Drivers, Sink Current Adjustment by External Resistance, Soft Start Function , Integrated protection circuit TSD (Thermal Shut Down) .

LED power Meter circuit is a simple RF detector using diodes to charge a capacitor. The voltage developed across the capacitor is indicated by a multimeter set to a low voltage range. The circuit is soldered together without the need for a PC board, as can be seen in the diagram below and paper clips are used for the positive and negative terminals of the multimeter.

The level power output of an FM transmitter is indicated by the illumination of a LED and the voltage reading on the multimeter gives a further indication of the output.

A digital multimeter may be used but the presence of RF may produce a false reading. Likewise, the radiated energy may upset some analogue meters and you may get full scale deflection on the 15v range as well as the 250v range! But the LED wont lie. It will accurately indicate the RF and you can see the change in brightness as you adjust the coils in the output stage. Some of the cheapest and simplest multimeters will give the best results as they have a low sensitivity and the radiated RF energy will not induce a reading. Even a damaged multimeter can be used, provided the 10v or 15v DC scale is operating.

The reading is not calibrated and does not represent milliwatts output. It is only a visual indication. 

We have designed over 10 FM transmitters for inclusion in the pages of this e-magazine and each one has different features and characteristics. Some are designed for 3v operation, some are for 9v operation, some are stable for hand-held situations and others are designed for high output. The illumination of the LED will range from barely visible to very bright. 

1 - 470R

1 - 100p ceramic

1 - 100n ceramic

2 - 1N 4148 diodes

1 - 5mm Red LED

1 - 2in (5cm) hook-up wire

2 - paper clips

No PC board required

The electronic circuit provides a visual time 9 second delay using ten LED before control by closing a 12 Vdc relay. That the reset switch has closed, IC 4017 decade counter will be reset to zero count which illuminates the LED driven from pin 3. IC 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower trigger point, or about 3 Vdc.

9 Sec Timer with LED Indication and Control Relay Circuit Schematic
 

That time the switch is opened, the transistor in parallel with the timing capacitor (22uF) is shut off allowing the capacitor to begin charging and the IC 555 timer circuit to produce an approximate one second clock signal to the decade counter. The counter advances on each positive going change at pin 14 and is enabled with pin 13 terminated low. When the 9th count is reached, pin 11 and 13 will be high, stopping the counter and energizing the relay. Longer delay times can be obtained with most capacitor or most resistor at pins 2 and 6 of the IC 555 timer.

In the circuit below, 60 individual LEDs are used to indicate the minutes of a clock and 12 LEDs indicate hours. The power supply and time base circuitry is the same as described in the 28 LED clock circuit above. The minutes section of the clock is comprised of eight 74HCT164 shift registers cascaded so that a single bit can be recirculated through the 60 stages indicating the appropriate minute of the hour. Only two of the minutes shift registers are shown connected to 16 LEDs. Pin 13 of each register connects to pin 1 of the next for 7 registers. Pin 6 of the 8th register should connect back to pin 1 of the first register using the 47K resistor. Pins 2,9,8, 14 and 7 of all 8 minutes registers (74HC164) should be connected in parallel (pin 8 to pin 8, pin 9 to pin 9, etc.).

The hours section contains two 8 bit shift registers and works the same way as the minutes to display 1 of 12 hours. Pin 9 of all 74HCT164s (hours and minutes) should be connected together. For 50 Hertz operation, the time base section of the circuit can be modified as shown in the lower drawing labeled "50 Hertz LED Clock Time Base". You will need an extra IC (74HC30) to do this since it requires decoding 7 bits of the counter instead of 4. The two dual input NAND gates (1/2 74HC00) that are not used in the 50 Hertz modification should have their inputs connected to ground.

72 LED Clock  Circuit Diagram



When power is applied, a single "1" bit is loaded into the first stage of both the minutes and hours registers. To accomplish this, a momentary low reset signal is sent to all the registers (at pin 9) and also a NAND gate to lock out any clock transitions at pin 8 of the minutes registers. At the same time, a high level is applied to the data input lines of both minutes and hours registers at pin 1. A single positive going clock pulse (at pin 8) is generated at the end of the reset signal which loads a high level into the first stage of the minutes register. The rising edge of first stage output at pin 3 advances the hours (at pin 8) and a single bit is also loaded into the hours register.

50 Hertz LED Clock Timebase

Power should remain off for about 3 seconds or more before being re-applied to allow the filter and timing capacitors to discharge. A 1K bleeder resistor is used across the 1000uF filter capacitor to discharge it in about 3 seconds. The timing diagram illustrates the power-on sequence where T1 is the time power is applied and beginning of the reset signal, T2 is the end of the reset signal, T3 is the clock signal to move a high level at pin 1 into the first register, T4 is the end of the data signal. The time delay from T2 to T3 is exaggerated in the drawing and is actually a very short time of just the propagation delay through the inverter and gate.

Two momentary push buttons can be used to set the correct time. The button labeled "M" will increment the minutes slowly and the one labled "H" much faster so that the hours increment slowly. The hours should be set first, followed by minutes.

This white LED driver electronic project circuit is designed using the MAX1573 integrated circuit , manufactured by Maxim Semiconductor.This white led driver circuit circuit drives as many as four white LEDs in parallel from a 3.3V source, and adjusts the total LED current from 1mA to 106mA, in 64 steps of 1dB each .To control the LED brightness, op amp U2 monitors the difference between the high-side voltage and the wiper voltage of digital potentiometer U1. The op amp then multiplies that voltage by a gain to set the maximum output current.



Zero resistance at the pots W1 terminal corresponds to minimum LED current, and therefore minimum brightness. Because the SET voltage is fixed (at 0.6V), any voltage change at the left side of R5 changes ISET, and the resulting change in LED currents changes their brightness level. R5 sets the maximum LED current: R5 = 215x0.6/ILED(Desired) (ILED is the current through one LED) .U1 integrated circuit is a digital potentiometer with logarithmic taper and an analog-voltage wiper for which each tap corresponds to 1dB of attenuation between H1 and W1 (pins 11 and 9).