Showing posts with label led. Show all posts
Showing posts with label led. Show all posts
Friday, July 12, 2013
LED Driver for Automotive Applications using AT9933
Using the AT9933 variable frequency PWM controller IC, can be designed a very simple and high efficiency LED lamp driver using a low-noise boost-buck topology.The AT9933 uses patent pending hysteretic current-mode control to regulate both the input and the output currents.
This enables superior input surge immunity without the necessity for complex loop compensation. Input current control enables current limiting during startup, input under-voltage and output overload conditions. The AT9933 provides a low-frequency PWM dimming input that can accept an external control signal with a duty cycle of 0 - 100% and a high dimming ratio.
This LED driver electronic project , require an input voltage range between 9 and 16 volts and will provide an 28 volt output at a maximum output current of 350 mA .The switching frequency of this electronic project is 350kHz . Values for components are : L1 = 82μH,L2 = 150μH,C1 = 0.22μF , RCS2 = 1.65Ω 1/4W, RREF2 = 10kΩ 1/8W, RS2A = 100Ω 1/8W,RS2B = 5.23kΩ 1/8W, RCS1 = 0.228Ω 1W, RREF1 = 10kΩ 1/8W,RS1 = 4.42kΩ 1/8W .
This enables superior input surge immunity without the necessity for complex loop compensation. Input current control enables current limiting during startup, input under-voltage and output overload conditions. The AT9933 provides a low-frequency PWM dimming input that can accept an external control signal with a duty cycle of 0 - 100% and a high dimming ratio.
This LED driver electronic project , require an input voltage range between 9 and 16 volts and will provide an 28 volt output at a maximum output current of 350 mA .The switching frequency of this electronic project is 350kHz . Values for components are : L1 = 82μH,L2 = 150μH,C1 = 0.22μF , RCS2 = 1.65Ω 1/4W, RREF2 = 10kΩ 1/8W, RS2A = 100Ω 1/8W,RS2B = 5.23kΩ 1/8W, RCS1 = 0.228Ω 1W, RREF1 = 10kΩ 1/8W,RS1 = 4.42kΩ 1/8W .
Thursday, July 11, 2013
Car Battery Voltmeter with LED Indicator
The circuit was developed to create a voltmeter that will be used to test car batteries while showing an indication using LEDs.
This circuit will function as a comparator and will measure the car battery voltage with an interval or step of 1 V. The voltmeter will be connected across the battery terminals then starting the car. The voltage of the battery should not be measured below 10 V or else it will be considered as low in charge or low in water, since the water level of the battery should be about ¼ of an inch above the plates.
Car Battery Voltmeter with LED Indicator Schematic
By applying the voltage of the battery in the inverting inputs of the amplifiers, the indicated voltage on the voltmeter is compared with the reference voltages that are produced by the Zener diode D1. The Zener diode is a special kind of diode that permits the flow of current in just one or forward direction as a normal diode, but will also allow in the reverse direction if the voltage is above or larger than a certain value of the breakdown voltage. The measured value is just enough to provide good thermic stability.
The presence of 10K trimmer RV1 is to adjust the degree of voltage that is required or desired while the visual indication will originate from the four LEDs.
R1=1K2
R2-3-4=680R
R5=15K
R6=10K
R7-8-9-10=1K
D1=5V6 /0.5W Zener
D2-3-4-5=LED
IC1=LM324
RV1=10K trimmer
The main use of the car battery voltmeter is to monitor the life and performance of batteries. It can be mounted on the dashboard that shows the battery condition to easily monitor the electrical system voltage while driving. The measurement is done by switching off the engine as well all lights and accessories and switching on the key without starting the engine. The battery is full charge if the voltmeter reads 12 V or more while a voltmeter reading of much less than 12 V signifies the battery is either discharged or failing.
- Voltmeter – a device or an instrument used for measuring the electrical potential difference between two points of either alternating current or direct current electric circuit.
- LM324 – has internal frequency compensated for unity gain, large DC voltage gain, wide bandwidth, wide power supply range, very low supply current drain, low input biasing current, low input offset voltage, large output voltage swing and differential input voltage range equal to the power supply voltage.
This circuit will function as a comparator and will measure the car battery voltage with an interval or step of 1 V. The voltmeter will be connected across the battery terminals then starting the car. The voltage of the battery should not be measured below 10 V or else it will be considered as low in charge or low in water, since the water level of the battery should be about ¼ of an inch above the plates.
Car Battery Voltmeter with LED Indicator Schematic
By applying the voltage of the battery in the inverting inputs of the amplifiers, the indicated voltage on the voltmeter is compared with the reference voltages that are produced by the Zener diode D1. The Zener diode is a special kind of diode that permits the flow of current in just one or forward direction as a normal diode, but will also allow in the reverse direction if the voltage is above or larger than a certain value of the breakdown voltage. The measured value is just enough to provide good thermic stability.
The presence of 10K trimmer RV1 is to adjust the degree of voltage that is required or desired while the visual indication will originate from the four LEDs.
R1=1K2
R2-3-4=680R
R5=15K
R6=10K
R7-8-9-10=1K
D1=5V6 /0.5W Zener
D2-3-4-5=LED
IC1=LM324
RV1=10K trimmer
The main use of the car battery voltmeter is to monitor the life and performance of batteries. It can be mounted on the dashboard that shows the battery condition to easily monitor the electrical system voltage while driving. The measurement is done by switching off the engine as well all lights and accessories and switching on the key without starting the engine. The battery is full charge if the voltmeter reads 12 V or more while a voltmeter reading of much less than 12 V signifies the battery is either discharged or failing.
Wednesday, July 10, 2013
Make an Efficient LED Emergency Light Circuit
The article describes a very simple homemade emergency light circuit that can be used during power failures and outdoors where any other source of power might be unavailable. The circuit uses LEDs instead of incandescent lamp, thus making the unit very power efficient and brighter with its light output. Moreover, the circuit employs a very innovative concept especially devised by me which further enhances the economical feature of the unit.
We know that LEDs require a certain fixed forward voltage drop to become illuminated and it is at this rating when the LED is at it’s best, that is voltages which is around its forward voltage drop facilitates the device to operate in the most efficient way.
As this voltage is increased, the LED starts drawing more current, rather dissipating extra current by getting heated up itself and also through the resistor which also gets heated up in the process of limiting the extra current.
If we could maintain a voltage around an LED near to its rated forward voltage, we could use it more efficiently. That’s exactly what I have tried to fix in the circuit.
Since the battery used here is a 6 volt battery, means this source is a bit higher than the forward voltage of the LEDs used here, which amounts to 3.5 volts. The extra 2.5 volts rise can cause considerable dissipation and loss of power through heat generation.
Therefore I employed a few diodes in series with the supply and made sure that initially when the battery is fully charged; three diodes are effectively switched so as to drop the excess 2.5 volts across the white LEDs (because each diode drop 0.6 volts across itself).
Now as the voltage of the battery drops, the diodes series are reduced to two and subsequently to one making sure only the desired amount of voltage reaches the LED bank.
In this way the proposed emergency lamp circuit is made highly efficient with its current consumption, and it provides backup for a much longer period of time than what it would do with ordinary connections.
Saturday, July 6, 2013
MAX1573 White LED Driver Schematic
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).
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).
Wednesday, July 3, 2013
Simple LED flasher circuit using NE555 timer IC
This circuit consumes more power, but its advantage is when you need a variable flash rate, like for strobe circuits. You can actually use this circuit as a remote control for strobes that have a remote input. Of course, it has many other applications besides strobes.
- R1, R2, C1 and the supply voltage determine the flash rate. Using a regulated power supply will do much to insure a stable flash rate. For a variable flash rate, replace R1 with a 1 megohm pot in series with a 22k resistor.
- The duty cycle of the circuit (the percentage of the time LED 1 is on to the time it is off during each cycle) is deterimed by the ratio of R1 to R2. If the value of R1 is low in relationship to R2, the duty cycle will be near 50 percent. If you use both LEDs, you will probably want a 50 percent duty cycle. On the other hand, if R2 is low compared to R1, the duty cycle will be less than 50 percent. This is useful to conserve battery life, or to produce a strobe type effect, when only LED1 is used.
- The NE555 timer chip can be damaged by reverse polarity voltage being applied to it. You can make the circuit goof proof by placing a diode in series with one of the supply leads.
- The purpose of R3 and R4 is to limit current through the LEDs to the maximum they can handle (usually 20 milliamps). You should select the value of these according to the supply voltage. 470 ohms works well with a supply voltage of 9-12 volts. You will need to reduce the value for lower supply voltages.
- Rainbow Kits offers several kits to build the above circuit. You can also order these kits from RadioShack.com. The Radio Shack catalog numbers (and web pages) are as follows: standard kit with two 5mm red LEDs, (990-0067), kit with two red, two green and two yellow 3mm LEDs, (990-0063), kit with jumbo green LEDs, (990-0048), kit with jumbo red LEDs, (990-0049). You can also buy all the parts to build the circuit at your local Radio Shack store, including a circuit board (276-159B).
I have built a miniature strobe circuit as follows. Use a 250k pot in series with a 4.7k resistor for R1. The 4.7k resistor sets the upper flash rate limit. Use 2.2k for R2. That sets a really short duty cycle. For this circuit, you dont use LED 2 or R4. For LED 1, I used a two Radio Shack white LEDs in series and no R-3. The circuit runs on a 9 v battery. link
Monday, April 8, 2013
LED Power Meter
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.
LED Power Meter Parts
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
Saturday, March 23, 2013
Temperature Candle Using LED
LED based projects require a lot of skill and hence only experienced circuit designers try out these circuits. But there are also a few circuits in this genre that can be done by amateur electronic hobbyists. The temperature candle is one such circuit. Read on to know more about this.
The hardware components that are required to build this circuit are listed below:
- Microcontroller
- Temperature Sensor
- RGB LED
- PCB
The circuit design is pretty simple. The LED is made to flicker by the microcontroller and the color is based on the ambient temperature at that point. The temperature of the room can be known by observing the color of the LED.
The temperature value is obtained in degree Celsius. This value is received as a result of pressing the reset button on the PCB. This value can also be obtained by providing power to the device. Once the device is powered up, the change in temperature is indicated. The blue LED is triggered for a temperature increase of 10 degrees. The red LED is triggered for a temperature increase of a single degree.
Suppose, the ambient temperature is 23 degrees celsius, The circuit works in such a way that the blue LED is made to blink twice and the red LED is made to blink 3 times. Soon after this, an orange colored flicker is observed as the LED goes into canfle mode.
Since through hole components are used in this circuit, it is very cheap to construct and the components can be easily soldered. The circuit also contains a jack for connecting to a Microchip Pickit 3 programmer / debugger. This reduces the complexity involved in code modification and download.
Friday, March 22, 2013
Make Interesting Flasher and Fader LED Circuits Using IC 555
The astable multivibrator mode is the most fundamental mode of operation of the IC 555. In this mode it basically functions like a free running oscillator. If this oscillator rate is reduced sufficiently, can be used for driving LED lights.
The wiring at the output can also be further modified for achieving interesting variations and light illumination patterns over the connected LED. Some of the practical ways of this is explained here, circuits diagrams of LED flasher, ghost effect generator, alternate blinker, light fader etc are also included.
The article explains a few interesting and simple LED blinker circuit configurations using the ubiquitous IC 555. The basic flashing mode has been kept intact yet various different attributions are provided to the circuit with its flashing rate and pattern.
The IC 555 is a complete package for the hobbyists. You can build numerous interesting circuits with this chip and make it to work as virtually any way you desire. Though the circuit provides us with many application ranges, flashers configurations are more commonly associated with these chips. These can be made to blink all types of lights at different rates depending upon individual preferences. You can flash LEDs, torch bulbs, string lights or even mains AC lamps with circuits incorporating this IC.
Basically, to configure the IC as a flasher or blinker, it’s connected with its fundamental astable mutivibrator mode. This configuration in fact requires just a couple of resistors and a couple capacitors to kick start the said functions. Once the chip is assembled as an astable, we can go ahead and enhance the output in many different ways to get outstanding visual treats.
Let’s learn how a few fabulous IC 555 circuits with LED can be built with the following discussions, but first we would like to know what materials are needed for this.
Being a hobbyist you would want to have a bunch of assorted resistors in your box of goodies and also some selected values of capacitors. For the present projects you would require a handful of different value resistors and capacitors.
Parts List
Resistors rated at ¼ watt, 5 %, unless otherwise stated.
Resistors – 1 K, 10 K, 680 Ohms, 4.7 K, 100 Ohms, 820 Ohms, 1 M etc.
Capacitor – 0.01 uF, 470 uF, 220 uF, 1 uF
Zener diode – 5.1 volts, 400 mW
LED – Red, Green, Yellow 5mm
Circuit Ideas
The first figure shows the basic configuration associated with 555 ICs, here it is connected as an astable multivibrator. The resistors and the capacitor 1 uF can be experimented with to get different rates of blinking over the connected LED. The LEDs can also be used with oter colors.
The 1 K resistor can be replaced with lower values for increasing the intensity of the LED, however it should not be redced below 330 Ohms.
Alternatively the 1 M resistor can be interchanged with a pot for attributing the circuit with variable blinking rate feature.
Making a Police Revolving Light Effect
The above circuit can be suitably modified for producing a revolving, flashing police light effect to the above constructed circuit. Here by adding a network of a zener diode / resistor / capacitor, to the output of the circuit, just as shown in the figure, we can acquire a very peculiar effect with the generated illuminations of the LED. The LED initially glows bright, then slowly dies down, but intermittently gives a high intensity pulse producing the discussed police warning roof light indicator illusion.
Random Light Effect Generator
The configuration shown in this figure enables us to use the circuit to generate random light patterns over the connected group of LEDs. As shown, three LEDs are connected in conjunction with a couple of resistors and a capacitor. The two LEDs connected in parallel but with opposite polarity, flasg alternately at a particular rhythm while the third LED fluctuates at some other random rate.
The above effect can be simplified by the circuit shown below. Here, the LED which is connected to the 1 K resistor blinks at the fixed blinking rate, but the next LED which is connected to the ground switches rapidly at some other defined rate.
Adding a Spooky Effect to the LED
If you want to produce some strange illumination pattern over the LED discussed through the above circuits, them it can be simply done using just a couple of resistors at the output of the IC. As can be seen in the figure, two resistors and a single resistor are connected at the output of the IC in a special way. The network switches ON the LED sharply, but switches it OFF slowly, producing quite a creepy visual effect.
Alternate Blinker
This configuration is pretty straightforward, as we all know; two LEDs can be connected to the IC output for generating an alternate blinking pattern over the connected LEDs.
The above circuit can be further modified as shown below by complely disarranging the network with the shown type. Here the LEDs though blink alternately, the intensity may fluctuate from dim to bright over the LEDs.
Light Fader Circuit Using IC 555
A very interesting light fading effect can be achieved by wiring up the IC 555 circuit as per the diagram shown below. The circuit switches ON the LED very gradually and does the same while switching it OFF, that is instead of shutting it off abruptly, does it very slowly.
Subscribe to:
Posts (Atom)