Showing posts with label LED. Show all posts
Showing posts with label LED. Show all posts

12 Volt DC Fluorescent Lamp Circuit Diagram

8:45 AM | Labels:

A number of people have been unable to find the transformer needed for the Black Light project, so I looked around to see if I could find a fluorescent lamp driver that does not require any special components. I finally found one in Electronics Now. Here it is. It uses a normal 120 to 6V stepdown transformer in reverse to step 12V to about 350V to drive a lamp without the need to warm the filaments.

12 Volt DC Fluorescent Lamp Driver circuit diagramParts:

C1 100uf 25V Electrolytic Capacitor
C2,C3 0.01uf 25V Ceramic Disc Capacitor
C4 0.01uf 1KV Ceramic Disc Capacitor
R1 1K 1/4W Resistor
R2 2.7K 1/4W Resistor
Q1 IRF510 MOSFET
U1 TLC555 Timer IC
T1 6V 300mA Transformer
LAMP 4W Fluorescent Lamp
MISC Board, Wire, Heatsink For Q1

Notes:
  1. Q1 must be installed on a heat sink.
  2. A 240V to 10V transformer will work better then the one in the parts list. The problem is that they are hard to find.
  3. This circuit can give a nasty (but not too dangerous) shock. Be careful around the output leads.

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Make a Warning Light and Marker Light Circuit Diagram

10:59 AM | Labels:

Make a Warning-light-and-marker-light. This is a led flasher light, A flashing light of high brightness and short duty cycle is often desired to provide maximum visibility and battery life. This necessitates using an output transistor, which can supply the cold filament surge current of the lamp while maintaining a low saturation voltage. The oscillation period and flash duration are determined in the feedback loop, while the use of a photo transistor sensor minimizes sensitivity variations.

Warning Light and Marker Light Circuit Diagram
Warning Light and Marker Light Circuit Diagram

Warning Light and Marker Light Circuit Diagram

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Simple Miser Flash Circuit Diagram

5:41 AM | Labels:

A flashing LED at the doorstep of your garage or home will trick the thieves into believing that a sophisticated security gadget is installed. The circuit is nothing but a low-current drain flasher. It uses a single CMOS timer that is configured as a free running oscillator using a few additional components. As the LED flashes very briefly, the average current through the LED is around 150 µA with a high peak value, which is sufficient for normal viewing. This makes it a real miser.

The 9V battery source is connected via ‘on’/‘off’ switch S1 to the circuit. When switch S1 is closed, the IC receives power from capacitor C1, which is constantly charged through resistor R1. As capacitor C1 delivers power to IC1, it saves the battery from drain.

 Simple Miser Flash Circuit Diagram
 

Most LEDs consume a current of 20 mA, which in many instances is higher than the power consumed by the rest of the circuit. This is undesirable if the device is battery-powered. In this circuit, the energy consumed by the LED is a small fraction of the normal value. Capacitor C2 charges through resistor R2 and diode D1. 

When the voltage across C2 reaches two-third of the supply voltage, threshold pin 7 of IC1 switches on as a current sink. The capacitor discharges through LED1 into pin 7 rapidly. Diode 1N4148 (D1) provides the one-way charging path for capacitor C2 via resistor R2. LED1 illuminates briefly for a while with the accumulated charges in C2. Again, the charging cycle repeats. This way, LED continues flashing. A 9V PP3 battery can perfectly handle this job.


Sourced by: EFY. Author  T.A. Babu

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Multiple Applications of High-Power LEDs

4:57 AM | Labels:

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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Power-on Reminder with LED Lamp Circuit Diagram

9:21 AM | Labels:

D. Mohan Kumar is famous name in the circuits world. There are d's Power-on Reminder with LED Lamp Circuit Diagram creation. Many a times equipment at workstations remain switched on unnoticed. In this situation, these may get damaged due to overheating. Here is an add-on device for the workbench power supply that reminds you of the power-on status of the connected devices every hour or so by sounding a buzzer for around 20 seconds. It also has a white LED that provides good enough light to locate objects when mains fails.

Power-on Reminder with LED Lamp Circuit Diagram

Power-on Reminder with LED Lamp Circuit Diagram
 
 Fig. 1 shows the circuit of power-on reminder with LED lamp. Here, IC NE555  (IC1) is wired as an astable multivibrator, whose time period is set to around six minutes using resistors R1 and R2, preset VR1 and capacitor C1 for sounding the buzzer every hour. The output of IC1 is fed to the clock input of IC CD4017 (IC2). Capacitor C3 and resistor R3 provide power-on-reset pulse to IC2.When power to the circuit is switched on, pin 3 of IC2 goes high. After around one hour, its output pin 11 (Q9) goes high and the buzzer sounds. This cycle repeats until the two npn transistors. The LDR offers a very high resistance in darkness, i.e., when no light falls on it. Therefore when power fails, transistor T1 gets reverse biased to drive transistor T2 and the white LED (LED2) glows. The lamp circuit is powered by a 9V rechargeable battery, which is charged via resistor R5 when mains is present. Thus in darkness, the LED remains power to the circuit is switched off.

Power-on Reminder with LED Lamp Circuit Diagram 1

 The automatic lamp is built around a light-dependent resistor (LDR) and ‘on.’Fig. 2 shows the power supply circuit. The AC mains is stepped down by transformer X1 to deliver a secondary output of 15V AC at 500 mA. The transformer output is rectified by a bridge rectifier comprising diodes D1 through D4, filtered by capacitor C5 and regulated by IC 7812 (IC3) to provide regulated 12V to the circuit. Capacitor C6 bypasses any ripple in the regulated output.

Sourced By: EFY Author D. Mohn Kumar

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Build a Rechargeable Torch Based on White LED

3:23 AM | Labels:

Rechargeable torches don’t come without problems. You need to replace the bulbs and charge the batteries frequently. The average incandescent light-emitting diode (LED) based torch, for instance, consumes around 2 watts. Here’s a rechargeable white LED-based torch that consumes just 300 mW and has 60 per cent longer service life than an average incandescent torch.

 Rechargeable Torch Based on White LED Circuit Diagram


Rechargeable Torch Based on White LED Circuit Diagram

Fig. 1 shows the circuit of the rechargeable white LED-based torch. The reactive impedance of capacitors C1 through C3 (rated for 250V AC) limits the current to the charger circuit. The resistor across the capacitors provides a discharge path for the capacitors after the battery is charged. The red LED1 indicates that the circuit is active for charging.

The torch uses three NiMH rechargeable button cells, each of 1.2V, 225 mAH. A normal recharge will take at least 12 hours. Each full recharge will give a continuous operational time of approximately 2.5 hours. Recharge the battery to full capacity immediately after use to ensure its reliability and durability. The charging current is around 25 mA.

Build a Rechargeable Torch Based on White LED

A voltage booster circuit is required for powering the white LEDs (LED2 through LED4). An inverter circuit is used to achieve voltage boosting. Winding details of the inverter transformer using an insulated ferrite toroidal core is given in the schematic. The number of 35 SWG wire turns in the primary and secondary coils (NP and NS) are 30 and 3, respectively. If the inverter does not oscillate, swap the polarity of either (but not both) the primary or the secondary winding. A reference voltage from resistor R5 provides a reflected biasing to the transistor, and keeps the output constant and regulated. The suggested enclosure for the torch is shown in Fig. 2.



Author: T.A . Babu

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Simple Emergency Lamp and Turning Indicator Circuit Diagram

8:53 PM | Labels:

This is a Simple Emergency Lamp and Turning Indicator Circuit Diagram.White LEDs are replacing the conventional incandescent and fluorescent bulbs due to their high power efficiency and low operating voltage. These can be utilised optimally for emergency lamp and vehicle turning indication. The circuits for the purpose are given here.

Emergency Lamp and Turning Indicator Circuit Diagram
Emergency Lamp and Turning Indicator Circuit Diagram fig 1

Fig. 1 shows the circuit of a white-LED based emergency lamp. You can also use arrays of white LEDs as daytime running lamps in automobiles. In the emergency lamp, seven 1.2V AA-size Ni-Cd cells giving 8.4V have been used as the power source. The brightness is controlled by duty-cycle variation of an astable multivibrator working at 1 kHz. The astable multivibrator is built around IC1. Its output is connected to LED-driver transistor T1. Up to six branches of white LEDs can be connected in parallel, with each branch containing two LEDs in series (only three branches are used here). Depending on the application, different combinations of battery voltages and the number of LEDs in series can be made such as to keep the resistive losses low.

Emergency Lamp and Turning Indicator Circuit Diagram fig 2

The charger circuit for a Ni-Cd battery is shown in Fig. 2. When the battery voltage is less than 9.8V, charging takes place since the voltage at the emitter of transistor T2 (VE) is 9.8V. The value of resistor R8 is chosen such that the battery charges at a rate of 70 mA per hour. The full charge voltage of the battery is 9.8V. When the battery reaches full voltage, the current reduces to approach the tickle charge value of few milliamperes.

Assemble both the circuits shown in Figs 1 and 2 on a general-purpose PCB. LEDs can also be mounted on the reflector of a lamp. After assembling, connect points A and GND of the emergency lamp circuit to the respective points of the battery charger circuit. Now your emergency lamp is ready to work.

To use the emergency lamp, switch on the circuit using switch S1. All the LEDs (LED1 through LED6) will glow to provide sufficient light.

Emergency Lamp and Turning Indicator Circuit Diagram fig 3


Turning indicator shown in Fig. 3 is another application of the LEDs. It can be used for two-wheelers and draws limited power from the dynamo/battery. At low revolutions, headlight dims because of the increase in load. The white LED-based turning indicator circuit draws a fraction of the power drawn by conventional bulbs, and may last longer than the vehicle itself.The circuit comprises two identical sections for left and right turn indications. 

The right turn indicator circuit is built around transistors T3 through T5 and white/yellow LEDs (LED8 through LED13). Similarly, the left turn indicator circuit is built around transistors T4, T6 and T7 and white/yellow LEDs (LED15 through LED20). Transistor T4 and the piezobuzzer are common for both-side indicators.

When you slide switch S2 towards right, blinking LED7, right-front LEDs (LED8 through LED10) and rear LEDs (LED11 through LED13) start blinking. Similarly, when you slide switch S2 towards left, blinking LED14, left-front LEDs (LED15 through LED17) and rear LEDs (LED18 through LED20) start blinking.Transistor T3 acts as the buffer, while transistor T4 drives the buzzer. Transistors T5 and T7 drive the LEDs.The LED array can be built using white LEDs or yellow LEDs depending on the colour of the indicator’s cover. 

In case you use yellow LEDs, keep in mind that the forward drop voltage is around 1.8V for a single yellow LED and therefore the value of the resistance should be changed in accordance with the increase in the number of LEDs in series.Three white LEDs produce the light intensity of six yellow LEDs.



Copyrighted: EFY : Authors: Anantha Keshava and Shireen M. Baretto

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Holiday Lighting Sequencer Circuit Diagram

10:24 PM | Labels:

Flasher bulbs use a bi-metallic strip which interrupts the series circuit when the lamp becomes hot.. This is a Best Holiday Lighting Sequencer Circuit Diagram. This is Integrated circuit Ul (a 555 oscillator/timer) is wired as a conventional pulse generator. The frequency of the pulse generator is controlled by potentiometer Rll. Resistor R2 puts a reasonable limit on the highest speed attainable. The output of the pulse generator is fed to the common clock input of U2, a 74C175 quad D-type flip-flop. 

 Best Holiday Lighting Sequencer Circuit Diagram

  Best Holiday Lighting Sequencer Circuit Diagram
Each flip-flop is configured so that its Q output is coupled to the D input of the subsequent flip-flop. Information on the D input of each flip-flop is transferred to the Q (and Q) outputs on the leading edge of each clock pulse. Switch S2 allows you to invert the information on the D input of the first flip-flop at any time during the cycle. This allows you to create a number of different sequences, which are determined by the state of the CQ output at the time of the switching. 
However, if S2 is switched to position while all outputs are high or all are low (which seldom occurs), the sequence stops and the outputs remain either all on or all off. If that happens, you only need to switch back to position A for at least one pulse duration, then back to position again. Likewise, S2 should be in position A (pin 4 connected to pin 14) each time the power is turned on. This is because the data on pin 4 must be a logic 1 in order to start a sequence; otherwise all outputs remain at logic 0, regardless of the clock pulses. Each output of the sequencing circuit is connected to an MOC3010 opto isolator/coupler (U3 through U6), which contains an infrared-emitting diode with an infrared-sensitive diac (triac driver or trigger) in close proximity. The diac triggers the triac, which carries the 117-volts ac. 
Each time that the infrared- emitting diode receives a logic 1, it turns on and causes the diac to conduct. With the opto isolator/coupler`s internal diac conducting, the triac turns on, and power is supplied to whatever load is plugged into the corresponding ac socket. So, the sequencing circuit and the 117-V ac outputs are optically coupled and are effectively isolated from each other. Power for the sequencing circuit is provided by a 6.3-V miniature transformer. The output of the transformer is rectified by a four-diode bridge circuit, the output of which is filtered by CI (1000- electrolytic capacitor). Capacitor C3 is added at the supply pin of IJ2 to suppress transients. Sourced By: Circuitsstream

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Build a Flashing Light with Twilight Switch Circuit Diagram

4:39 AM | Labels:

Build a Flashing Light with Twilight Switch Circuit Diagram. Flashing light is very useful in order to indicate any obstruction or working in progress. The project automatic flashing light with twilight switch flash light in dark but during day it automatically turns off itself.

The circuit diagram of automatic flashing light with twilight switch is shown below where LDR is used as sensor. In the presence of light LDR offer low resistance and in dark it offers high resistance. When there is absence light, LDR offer high resistances which turn off the transistor T1. Due to this darlington pair made from transistor T2 and T3 is turn on which further glow bulb. The feedback from its output is given to the junction of resistor R2 and LDR as shown in circuit diagram. Due to feedback this circuit works as oscillator which work as flasher. Variable resistor VR1 is used to adjust the sensitivity of LDR.

Flashing Light with Twilight Switch Circuit Diagram
 
Flashing Light with Twilight Switch Circuit Diagram
 


PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1 = 2.2 KΩ
R2, R3 = 1 KΩ
R4 = 3.3 KΩ
VR1 = 25 KΩ
Capacitors
C1 = 1 µF – 10 µF
Semiconductors
T1, T2 = BC547B
T3 = BEL187-P
Miscellaneous
LDR
B1 = 3V to 10V bulb

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Build a 16 LED Chaser Circuit Diagram

9:04 AM | Labels:

This 16 LED Chaser Circuit Diagram is a double direction flash. Similar to Digital Ping- Pong 1, there is a movement of a lit dot, up and down along the LED's length.

16 LED Chaser Circuit Diagram

16 LED Chaser Circuit Diagram


When the D16 lit the situation changes and there is a reverse movement. Lit D15-14 ……D16, is lit making circles when the circuit is under power. The IC1 is an unstable flip- flop supplying with stable frequency pulses (the frequency can be changed by TR1, adjusting the velocity of the LED's up and down).

This frequency supplies the IC3 (which is a 4-Bit UP and DOWN counter) through 2 gates A-B of the IC2. The output counter supplies the IC4 that is the driver of the LED's. The parts C- D of The IC2, make a R-S flip- flop, that changes situation, when the edge LED's D1 and D16 lit.

We have an electronic limit for the situation change. In proportion the shape we make with the LED's, we can have the proportionate optional result, making various effects.

Part List

R1= 100Kohms
R2= 220Kohms
R3= 470 ohms
TR1= 1Mohms
C1= 330nF 100V MKT
D1-16= LED 5mm
IC1= 555
IC2= 7400
IC3= 74193
IC4= 74154

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Simple Voltage-to-Current Converter Drives White LEDs

10:23 AM | Labels:

You sometimes need to drive a white LED from one 1.5V battery. Unfortunately, the forward voltage of a white LED is 3 to 4V. So, you would need a dc/dc converter to drive the LED from one battery. Using the simple circuit in Figure 1, you can drive one white LED or two series-connected green LEDs, using only a few components. The circuit is a voltage-to-current converter, which converts the battery voltage to a current that passes through the LED.

You can adjust this current and, thus, the brightness of the LED, by varying resistor R3. If you turn on switch S1, resistor R2 feeds base current to transistor Q2. Q2 turns on, and its collector current, via R3, turns on Q1. Now, the current through inductor L1 increases. The slope of the increase is a function of the value of L1 and the battery voltage. The current through L1 increases until it reaches a maximum value, which depends on the gain of Q1. Because the value of R3 sets the base current drawn from Q1, Q1's collector current is also limited.

White LEDs Circuit Diagram

White LEDs Circuit Diagram


Once the current through L1 reaches its maximum value, the slope of the current through L1 changes. At that instant, the voltage on L1 switches to a negative polarity forced by the changed slope. This negative voltage traverses capacitor C1 and turns off Q2, which in turn turns off Q1. The negative voltage on L1 increases until it reaches the forward voltage of the LED. The peak current through inductor L1 now flows through the LED and decreases to zero. Now, Q2 switches on again, via the current through R2, and the cycle starts again.

By adjusting resistor R3, you can set the peak current through L1 and the peak current through the LED. The brightness of an LED is a linear function of the current through the LED. So, adjusting the value of R3 also adjusts the brightness of the LED.

It doesn't matter which LED you use; the forward voltage on the LED always increases until the peak current through L1 flows through the LED. Different forward voltages of the LEDs yield different on-times (duty cycles) but the same peak current through the LED. With the values shown in Figure 1, the circuit oscillates at a frequency of approximately 30 kHz and delivers a 20-mA peak current through the LED.

The duty cycle depends on the ratio of the battery voltage to the forward voltage of the LED. One advantage of this circuit is that it requires no series-limiting resistor for the LED. The peak current through the LED is a function of the value of R3 and the gain of Q1.[via]

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The Nite Rider Lights Circuits Diagram

9:16 AM | Labels:

As a keen cyclist I am always looking for ways to be seen at night. I wanted something that was a novelty and would catch the motorists eye. So looking around at my fellow cyclists rear lights, I came up with the idea of 'NITE-RIDER'. NINE extra bright LED's running from left to right and right to left continuously.

It could be constructed with red LEDs for use on the rear of the bike or white LED's for an extra eye catcher on the front of the bike. All IC's are CMOS devices so that a 9V PP3 battery can be used, and the current drawn is very low so that it will last as long as possible.

Nite Rider Lights Circuits Diagram

The Nite Rider Lights Circuits Diagram


Parts
1 555 timer IC4.
1 4027 flip flop IC1.
2 4017 Decade Counter IC2 and IC3.
3 4071 OR gate IC5, IC6 and IC7.
1 470 Ohm resistor 1/4 watt R3.
2 10K resistors 1/4 watt R1 and R2.
1 6.8UF Capasitor 16V C1.
9 Super brght LED's 1 to 9.
1 9V PP3 Battery.
1 single pole switch SW1.
1 Box.

How This Circuit Works.

IC4, C1, R1 and R2 are used for the clock pulse which is fed to both the counters IC2 and IC3 Pin 14. IC1 is a Flip Flop and is used as a switch to enable ether IC2 or IC3 at pin 13. IC7a detects when ether IC2 or IC3 has reached Q9 of the counter pin 11. IC5, IC6 and IC7a protects the outputs of the counters IC2 and IC3 using OR gates which is then fed to the Anodes of the LED's 1 to 9.

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LED Heart PWM Fading

11:33 PM | Labels:

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]


LED Heart PWM Fading schematic

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Current Controlled Boost LED Driver and Black Soldermasks

11:32 PM | Labels:

The MAX16834 is a neat little chip (it's not the only one, there are plenty of others out there) that allows high efficiency designs for LED string driving. It provides a platform for a Buck or Boost converter design, as well as brightness adjustment via analog/PWM input pins, as well as a fault output (in case of open/short circuits for example) and also diverse other functionalities that can be quite useful. [Link]


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Simple Flashing LED

11:40 AM | Labels:

The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. A superbright’ red LED is used because this provides a bright flash with a low current.

If you want to use 4.5V supply by connecting 3 Alkaline cells or any other source, change the resistor along with LED from 3.3k to 1k for a better flash.
Note that AA cells will last longer than a 9V PP3 battery 

To flash two LEDs alternatively we have to increase the clock pulse speed to possibly fastest to have exact proper alternation.link

Parts Required:
  1. 100k potentiometer
  2. 10k and 3.3k
  3. 10mF
  4. LED
  5. 555 Timer
  6. 9v Battery

Circuit Diagram:
There are three different modes to flash an LED using 555 Timer
 


and their bread board arrangements
         

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Cell Phone RF Radiation Detector LED

11:42 AM | Labels:

From rookieelectronics: This is my favorite project, its too simple and very interesting because it does not require any voltage source. it converts RF frequency waves from cell phone (whenever you call or send a text) to little current to flash a LED.


Cell Phone RF Radiation Detector

Actually this project is also called as LED power meter, it is used to test RF equipments. It can detect output power of our FM transmitters, by simply connecting voltmeter in the place of the load(LED) of this circuit.

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Amazing Artificial LED Candle

11:41 AM | Labels:

The Akafugu LED Candle is an artificial candle that imitates the flickering of a real candle. Use it in place of a real tea candle: It will fit inside a tea candle casing or any holder made for tea candles.


Features:

  • Randomly flickering LED: Imitates a candle
  • Fits inside a tea candle casing
  • Open Source Firmware (available at GitHub)
  • Open Source Hardware: Eagle PCB design files available at GitHub
  • On-board ISP header for upgrading firmware

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8-Digit 7-Segment LED Display with SPI Interface

11:40 AM | Labels:

The following display features eight 7-segment displays arranged in two rows of four digits. The on-board MAX7219 driver enables you to easily add eight 7-segment LED displays to your project using only 3 I/O pins of microcontroller.


The major advantage of using this board is the time-division multiplexing operations required for continuous refreshing of the display digits are performed by the MAX7219 chip, thereby keeping the microcontroller free for doing other pressing tasks. It is suitable for displaying two variable values simultaneously in a project, such as displaying temperature and humidity, or current and voltage, etc. [Link]

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Auto-Brightness Adjustment to Seven Segment LED Displays

11:39 AM | Labels:

Raj from Embedded Lab shows in his latest tutorial guide how to implement adaptive brightness control to seven segment LED displays for optimum readability in all illumination conditions. The technique has been demonstrated by constructing a temperature and humidity meter that adapts the brightness of the seven segment LED displays to the surrounding lighting conditions.The project uses a general purpose LDR to sense the surrounding illumination and MAX7219 to drive the LED display.

Implementing Auto-Brightness Adjustment to Seven Segment LED Displays

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Simple High Power Triac Dimmable LED Driver

11:37 AM | Labels:

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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