A LED is a light emitting diode. Lighting a LED is considered the "Hello world" of a circuit design, and it can be as simple as putting a series resistor or can get more complicated, involving PWM and multiplexing.

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32 views

LED strip flashing to music

I'll give you the backstory: A few weeks ago, I used a popular enough circuit to create LED lights that flash to music. The circuit I used as a template is the first image in the imgur album ...
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1answer
102 views

How can I power this LED Matrix?

I'm controlling a 16x32 LED matrix with an Arduino and have it wired correctly (I think) but I'm having trouble with the power. I tried to follow the instructions from Adafruit but was unsuccessful in ...
1
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3answers
102 views

3 Watt LEDs in Series - Using constant voltage Source

I have searched everywhere for an answer to this question but I think its probably so simple that no one has felt the need to answer it. Basically I have 20 x 3 Watt LEDs and have a 80W Constant ...
0
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1answer
32 views

Identify high current LED Package name

Based on another question recently asked, this package is very common, used in high current LED applications (0.5W ~ 3W). The package includes the led chip, lens, heatsinking, but can vary in light ...
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5answers
106 views

Could somebody tell me which resistor to use with this LED

I went to my local electronics store and asked for a powerful LED because I wanna make a small flashlight. They gave me this thing, but the problem is that the stores in my area don't have any ...
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1answer
75 views

Red light therapy LED spotlight

What's the easiest way to mount a bunch of surface mount LEDs into an array or spotlight? There are a bunch of very interesting new papers on red light therapy for a variety of conditions. I want to ...
0
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1answer
69 views

problem with LED Matrix circuit

I want to create a LED Matrix circuit with 74HC595 shift register and 2n7000 mosfet. The schematic is as follows. I have mentioned voltage levels at various points. All the control signals of ...
0
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2answers
104 views

Night activated LEDs

I want to use a photo resistor to make a circuit like this But instead of light causing the led to turn on, I want darkness to cause the led to turn on.
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2answers
72 views

Is it possible to run 230V LED - or flourecent “spiral-tube” - lightbulb with a 9V battery?

I would like to power a 230V LED lightbulb with a 9V battery. I assume I'll have to dissect it... Surely there must be some sort of power-converter and rectifier from 230V-AC to something a lot ...
2
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4answers
266 views

Alternating between two LEDS using BJTs

I would like to control the output of two LEDs with a single pushbutton. When the button is open, D2 should be off and D3 should be on; when the button is closed, D2 should be on and D3 should be off. ...
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1answer
111 views

Most lumens per watt

I recently started designing a pcb for flashing lights I want to use in a pavillon at festivals, garden parties and the like. Now my question is, can anyone tell me which kind of LED that has the ...
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0answers
58 views

Poor output efficiency of SEPIC supercap driver

I'm attempting to drive a high power led (3.6V, 700mA, nominal power 3W) from a 5.4V 3F supercapacitor via a SEPIC (see this question). While I don't have any strict design requirements, a running ...
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1answer
42 views

bluetooth headset with LCD and memory

I was wondering if it is possible to create a bluetooth device which would have a LCD screen and some memory (1kb) for making and receiving calls. From my research ( and I am far from an EE, but ...
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2answers
58 views

What is current forward (if) of an IR LED

I see a lot current forward on datasheet, but I don´t know the difference from the "normal" current. EDIT On this datasheet, I saw a If (current forward) of 100mA and then on page 3 it states about ...
2
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1answer
96 views

Beam Angle vs Viewing Angle

I am looking at the product specs for an IR light and see that it has: Beam Angle: 50 deg Viewing Angle: 25 deg What is the ...
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2answers
49 views

Complex LED drivers/circuits [closed]

Throughout my travels I've seen these very complex circuits that incorporate ICs for "i.e. dimming applications" that are included in designs with buck boost converters, etc. What makes LED driving ...
7
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5answers
804 views

Question about resistors and LEDs

How can I find the right resistor to make 50% brightness in an led? I know how to find the right resistor to get the brightest but I'm wanting to find the perfect middle.
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1answer
57 views

What kind of RGB LEDs are these?

I bought these RGB flood lights cause I liked the LEDs I saw in them and I was wondering what kind they are so I can just buy the LEDs and not the whole flood light.
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2answers
82 views

Can I use a LED Driver to control a Solenoid?

I have on order an LED driver and I want to use it as a simple 12v DC output to control a Solenoid Valve. The Driver says Constant Current & Constant Voltage. I obviously don't want 1A pumped ...
0
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1answer
41 views

Color Changing LED Circuit upon power on

The circuit I plan to make will have 3 RGB LEDs in it and what I would Like is for it to change colour each time it turns on to a random colour. I'm a beginner level so any help will be greatly ...
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0answers
46 views

How to power Common Cathode RGB LED

I'm trying to figure out how to power a common cathode RGB LED. The setup I have below does not work. I assumed power would flow to R, G, and B, and there would be a white light; but nothing. Would ...
11
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2answers
973 views

High frequency blinking LEDs and sensor for that

I want to make LEDs blink rapidly. (more than 1000 blinks/sec., faster is better) First, I am curious that the common off-the-shelf LEDs have a capability of blinking with such a high frequency. ...
0
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1answer
74 views

I have a not working LED driver IC

I'm currently using a boost mode constant current LED driver IC LM3424. I used a MCU to PWM dimming the brightness of the LED, and schematic of LM3424 part is almost the same as it in LM3424 ...
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2answers
174 views

Transistor Ohms

I've built the circuit in the schematic below to control my TV, the D1 and D2 LEDs are the two mini LEDs from this IR Extender: I've cut it below the female headphone jack and I'm using my ...
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0answers
65 views

Maximum Ohms for IR LED and transistor

I bought a cheap IR extender and I'm trying to use the small sticky cases to control my TV using a Raspberry Pi. The extender has two "heads" with a small IR LED in it and they were connected to the ...
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2answers
73 views

Messing with rgb leds and have a question

I have some LEDs that I'm wanting to use in a project. I would like to know what's the best resistor I would need to get the most light out of the 3 different colors using a 12v source. I've measured ...
0
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0answers
34 views

LED bulb that works on both 64 volt DC and 110 AC

Can anyone advise on a reliable/cost-effective way to modify a screw-in LED light bulb so it will run on an AC power supply that has a battery backup where DC is provided in backup mode (this is for ...
2
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3answers
65 views

Shift Register turning on Transistor for LED Cluster

I have a question concerning using 74HC595 with two transistors to power a LED matrix. My goal is to make an 48 x 8 LED matrix using a cluster of 5 LEDS per unit (as opposed to only using one led as ...
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1answer
119 views

Two or more different regulators connected to one battery

I want to make batteries provide power to both a micro controller (Raspberry Pi) and a 4x4 LED matrix. A simple circuit diagram is shown below. (only one LED is drawn in the fig. But regard it as LEDs ...
0
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1answer
70 views

Constant current LED driver min / max current rating explanation

I currently have a 150-1500mA led driver that I sue to power a 30W LED. Driver has adjustable maximum current pins that I can use to change to match the maximum current. I have it set to 1050mA. I am ...
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1answer
42 views

How is possible to connect 3x 100w led lights to a 300w led driver?

Could you explain if is possible to connect 3x lamps of 100w to 300w led driver? The led driver specification is: constant current, 27-36v, 9A. The lights: 1x, 27-30v, 3.5A, and 2x, 30-36, 3A. So, ...
0
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3answers
76 views

Need assistance in identifying wire

I'm working on a LED project similar to the one in the picture, and I need to identify the black wire that the arrows are pointing to. What are those called? Here is a picture:
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1answer
74 views

Need help calculating resistor values for IR LED Driver

I'm wiring an IR LED driver for an Arduino project I'm prototyping. The Arduino will be run at 5V, and I'm planning on using it's 5V output to drive the transistor that runs the LED The circuit I've ...
3
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6answers
503 views

Reducing LED circuit current

Is there a way to reduce the current of a circuit? For example, I have this circuit: and I want to reduce the total current so it can last longer in a 12V battery.
0
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1answer
80 views

Arduino pin frequency for persistence of vision (POV) project

Arduino Uno has 4 pins that run at 960 Hz and 2 pins that run at 490 Hz. Are those frequencies fast enough that I can change the strips that lights up the LED and create the illusion that it lights ...
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3answers
77 views

Stable power for LED from 5.5 to 7.5V AC

About a year ago I posed the question "Making 12V DC from 6V AC". Since the conversion from AC was going to be problematic (for me), I tackled the tail/brake light first, because working with the 6V ...
0
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0answers
57 views

How to drive Worldsemi “smart” LEDs

Let's get to it: The issue is about these cheap 6-pin 5050 package LEDs from Worldsemi. These LEDs contain an IC with a simple serial interface running at 800kHz. You can daisy-chain those LEDs ...
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2answers
196 views

Arduino driver for lots of high power LEDs

This is my first Arduino/electronics project and I am a little bit confused about the components I need to handle huge amount of currents and the circuit. I want to have full control of 32 (maybe 40) ...
3
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1answer
76 views

Show numbers on LEDs

I'm a beginner in EE, so maybe the following question seems obvious to you. I have to design a circuit that get a number from 0 to 9 via a decimal keyboard, and then show the corresponding number on a ...
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4answers
122 views

Why is the led that I hooked up with my laptop blinking?

I connected a led to my laptop through a USB cable. I connected the red wire to the positive end of the LED and the black wire to the negative and of the LED. Why does the led keep blinking (pulsing) ...
2
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1answer
131 views

Theory behind the “Joule Ringer” circuit

The less-than-critical thinking free energy types are pointing to the "Super Joule Ringer" demonstrations online, where a quick touch with a 9 V battery illuminates an LED for hours. ...
0
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2answers
108 views

How to make a color-changing LED circuit that runs off of a coin cell

I've been curious for quite some time about the 2-lead RGB color-cycling LED's. I know that they have 3 tiny LED's inside and an IC, but I'm really curious to understand what's going on in the IC that ...
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2answers
66 views

Can I make pulsing light using AC as source, a diode and a LED?

I'm new to this branch of physics hence my stupid question. I know that diodes are used to make current flow in only one way. If I connected an AC source to a diode and the diode to a small light ...
0
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0answers
42 views

Confusion around LEDs on a breadboard [migrated]

I am just starting out with an Arduino Diecimila and am playing around with LEDs, and am confused by why some circuits result in an LED not lighting up. Successful Scenarios: Yellow LED from pin13 ...
0
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0answers
40 views

Preamp circuit LED driver

I was wondering if the this schematic would work in my scenario: My scenario is that I want to play an audio file from my phone, in which the audio file will be played from my phone which will be ...
0
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2answers
129 views

LED Bike light - blowing at high speeds? [closed]

My bicycle is equipped with a about 5 year old hub dynamo and a LED front- and backlight. I suspect the dynamo is a DC-generator though this likely may be false. But if its true, it would mean that ...
3
votes
1answer
66 views

RGB led driver maximum current

I am planning to build a device that includes an high power RGB LED (either a lightsaber or a decorative object for the girlfriend - I still have to decide), where high power means about 3x3W. I've ...
4
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3answers
247 views

LED persistence of vision (POV) project

I recently saw an article with a LED cube 8x8x8. I saw that it relies on an optical phenomenon called persistence of vision (POV). So I wanted to create a simple circuit with 4 lines each one with ...
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3answers
106 views

How many LEDs can I power with a 3.6V battery?

How can I calculate how many LEDs in parallel I can light with three 1.2V batteries in series? How long will 3.000mAh batteries last in that case? Do I have to put a resistor at only one of the ...
0
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0answers
66 views

Trying to use SPI to communicate between dsPIC (33EP) and LED driver (LT8500)

I'm trying to setup SPI to generate PWM signals on the LED driver LT8500. Below is my code: ...