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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46 views

Current regulator static analysis

I'm trying to make (and try to learn something better) about a simple current regulator. I need to make a complete static analisys before starting with the frequency one. But I've some thoughts about ...
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1answer
35 views

Analog/PWM Dimming signal for a LED driver (LIPO battery low-voltage cut-off)

I am using a 4S LIPO-battery and a commercial constant current LED driver to drive a LED setup. Data Sheet for the driver To avoid abusing the LIPO battery, I would like to build a low-battery ...
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1answer
29 views

How can I use an IO ports on Digilent Genesys Virtex 5 to drive 6 external leds?

I have a project which requires led output. Right now I'm using the onboard leds, but I would like to use 6 external LEDs instead. Which IO pins should I use, and how should this be done? I'm ...
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2answers
108 views

Connecting LEDs to 220v without using a power supply

I'm designing a backlit custom picture frame, and I want to include the power supply (or the lack of one) inside the body of the frame. The problem is, since the frame design is more or less thin, I ...
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1answer
79 views

How to drive external LEDs using Digilent Genesys (Virtex-5) FPGA? How to use pressure or IR sensor input?

I'm in a Reconfigurable Logic course. Our final project is to program a Digilent Genesys Virtex-5 FPGA board to simulate a traffic light controller for a 2-lane intersection, with outputs being the ...
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1answer
48 views

How to Hook-up an LED-Lit Rocker Switch with 115V AC Power W/o Blowing the LED?

This is the LED-Lit switch I have: The switch itself is rated for 10A125VAC/6A250VAC but there is also a "12V" label on the switch suggesting that the LED should be given 12V. Now, if I were to ...
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2answers
38 views

Constant current power supply and 2 LED - series or parellel?

I have a very limited understanding of how current works in parallel or in series. I am trying to connect a pair of LEDs to a constant current power supply (1200ma) in which the power supply ...
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5answers
75 views

Shortest time to visibly light LED

What is the shortest time (pulse 010) to visibly light a LED? Visibly = The human eye can see the LED blink. I use 5V as source and PIC16F628A@20MHz for the project. Here is a datasheet for the ...
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4answers
210 views

Which type of LEDs is a good source of light and can replace the sun

There is often no sun were I live so I need some advice for building a LED matrix that can replace the sun light and possibly avoid bad wavelength. UV produces vitamin D but upon reading ...
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1answer
51 views

Panic button alarm system circuit [on hold]

I'm a homeschool mom with absolutely minimal knowledge of electronics. How should the following panic button alarm system circuit look? Four cells connected parallel or series, two panic buttons ...
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2answers
541 views

What's the difference of placing multiple resistors and one resistor for limiting the current of LEDs?

I'm looking at a diagram and wondering if I could use just one resistor to limit the current of the LEDs instead of multiple resistors so that the cathodes are all connected to the same resistor. ...
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1answer
41 views

Power a laptop LED backlight with NiMH batteries

I'm powering a laptop LED backlight with an external 24,8V power supply, because I have problems with the internal WLED driver. The display used to work at 27V, but with the 24,8V of the power supply ...
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0answers
47 views

Calculate number of LEDs, and resistor values, when some is turned on/off from time to time?

The LEDs that I have available is 3.2V ~ 3.4V and 20mA (exLED 5mm LED). (i'm planning to use the clear ones). The resistors is 1/4W metal film resistors (1/4W Resistance Metal Film Resistors). And ...
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1answer
51 views

driving led current and voltage

I need help replacing a driver in my very underpowered 138w LED UFO grow light. i bought it for my son to grow chilli's and other consumables over winter months and also as something of a hobby. The ...
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1answer
61 views

Bypass IC output to give an LED a voltage boost

I'm attempting to modify a circuit in an existing device, the relevant part of which looks like this: The IC controls the LED brightness, as well as having connections to other things. I have ...
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1answer
52 views

Simple LED Dimming from Analogue Voltage Control

I have a circuit which switches 12V to power a 12V, 20mA LED (Marl 512-997-21, RS: 310-6921). I need to modify this to add some simple dimming control. The current circuit doesn't have any resistors ...
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0answers
36 views

Circuit that takes input signal and controls led

I am trying to design a circuit that compares a recorded signal to a stock signal. If they are not similar it then inputs a signal into a circuit which will change the pulse of the led to stimulate a ...
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3answers
235 views

LED bulb still emits light when turned off

I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. This one. The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state ...
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1answer
52 views

Change of RGB LED to cheaper one

Right now I'm reading Raspberry Pi Cookbook and I would like to create the program described in the book. Because I'm beginner and I would like to buy more (cheaper) RGB LEDs at once and also I will ...
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4answers
137 views

Flashing leds from bicycle tail light [closed]

I'm not sure if this is the right place but I'm a bit puzzled by this (cheap chinese) bicycle tile light. I opened it up, but I don't seem to get it working again. It has three components: the ...
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2answers
54 views

12 VDC LED strips get too hot [duplicate]

Package reads "2 8in 12vdc LED strips". Plugged into a car they get hot enough to melt. Plugged into a 12vdc 120mA transformer they work great. What resistor do I need to bring car amperage down to ...
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4answers
130 views

Turning on a led with negative voltage

I have been using this fuse blown indicator circuit for a bit, it basically works perfectly fine with positive voltages no matter if there is or nor a load connected The problem starts when I feed ...
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1answer
46 views

Arduino not driving RGB LED Strip

I'm using Arduino Uno with a 12V RGB Signal Amplifier and a 12V RGB LED strip. 12VDC is supplied to the amplifier. However the LED strips does not light up whether the PWN pins are set to either ...
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2answers
104 views

Calculating resistor's value to use it with a LED

There's something about the LED formula that I don't understand. It says that if I have one LED with a forward voltage of 3V and a forward current of 20mA then if I want to drive my circuit with a 6V ...
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4answers
83 views

Industrial flash (LED?) for rolling shutter

I am developing industrial monitoring system, at this moment with Raspberry Pi and its camera (this might change if it is not satisfactory). The camera will take still pictures of the scene once in a ...
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2answers
69 views

Is using a display panel as a light sensor conceivable?

Though the question may sound naïve at first, I still wonder if it would somehow be possible to use an LCD/TFT/OLED or other Panel as an image-sensor. From my understanding of how these kinds of ...
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3answers
98 views

Diode Drop vs Open Drain Output Tolerance

I have an LED Driver IC that states a 5.5V tolerant Open Drain Output. It's Absolute Maximum section indicates 6.5V with a note saying "The input negative-voltage and output voltage ratings may be ...
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0answers
78 views

LED and constant current [duplicate]

Want to build a grow light for plants using a full spectrum, now regarding the electrical side of it. using a constant current "CC" power supply, what kind of driver would I use to vary the amps to ...
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2answers
34 views

Equivalent of STP16C596 in DIP package for through-mount [closed]

I’m trying to add a large number of RGB LEDs (70, so 210 outputs) in a fairly small space (basically a keyboard, although it’s a bit bigger than most). I read on this tutorial and elsewhere about ...
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0answers
71 views

4x4x4 LED cube using 74hc595 shift registers

I am currently planning on building a 4x4x4 LED cube. It will be organised as 4 layers of 4x4 matrices where the cathode of each 16 LEDs are soldered together. The anode of each of the 16 LEDs are ...
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0answers
24 views

Rasp PI spectrum analyzer led strip length [migrated]

I'm new to raspberry-pi and electronics. I was looking to this tutorial: https://learn.adafruit.com/raspberry-pi-spectrum-analyzer-display-on-rgb-led-strip/page-1 Is it possible to build that ...
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1answer
85 views

Resistor set up to drop to 12V for LEDs

I generally work with 12V standard and simple DC wiring. Awhile back I put a bunch of LED lights on a bicycle for a Youtube video, though I ran them off of a single 9V battery. I would like to run two ...
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0answers
38 views

What led driver IC options I have to build 2-cell driver for 3W LED?

I need very small and light 3W flashlight/headlamp for kind of specyfic purpose. I want to use two AAA Eneloop cells. In datasheet there is discharge curve at 1.6A, so I guess I can discharge them ...
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0answers
41 views

Reference Current for many LED drivers

I am developing a project in which I need to control many LEDs simultaneously. Therefore, I am using many TLC5940PWP LED Drivers (which are driven themselves by small microcontrollers connected by an ...
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0answers
3 views

Are there 3-pin to 2-pin power connectors for motherboards [migrated]

My (old) case front panel has a 3-pin power led connector (inc. one empty slot in the middle). My (new) motherboard has a 2-pin power led connector. How do I connect the two? If I try to connect the ...
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1answer
81 views

I'm looking to create a simple circuit that will have 8 randomized “pulsing/fading” LED's

I am looking to make a simple (cheap, small spaced) circuit that will light 8 LEDs in a random order AND have a pulsing/fading in and out effect. I was originally going to program a randomized effect, ...
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2answers
99 views

LEDs, Voltage and Resistors

I noticed that a Christmas Light uses 20 LEDs in series parallel, operated by 2 AA batteries (3V) without a resistor. I thought you always need a resistor? Would it be possible to run them on 5V ...
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2answers
136 views

How to get the square wave output at Photodiode

LED flashing light captured by camera Displayed image detected by Photodiode I have a 2V p-p square wave signal of 500µs. This signal drives ...
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0answers
57 views

Bi-color LED for low and high-inpedence switching

I designed a circuit to make glow a green LED when a input pin is in high impedance state. When the input pin is connected to ground, Red LED must glow. I've been searching for a bi-color LED for this ...
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0answers
43 views

half wave rectifier connected to a dc motor

we have half wave rectifier connected to a dc motor load. by using a step down transformer from 8 to 1. by modalization we have the Primary Winding resistance is Rp=50 ohm and it's Lp=0.1 H the ...
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2answers
88 views

why when I touch the input cable or put my hand near it the LED comes on?

I am a beginner at electronics and recently got an arduino and the Arduino Project Handbook and I am having trouble with the push button led project. I have followed the directions and have the ...
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0answers
45 views

adjustable current driver for high power LED

I am trying to driver 3 high power RGB LED "Edixeon RGB" I want the current to be able to vary from 0 to 350 mA I am using three classical linear circuit, one for each color, with a current sensor ...
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0answers
33 views

Arduino's Serial Monitor Showing Constant Value [migrated]

I have a breadboard Arduino; made with ATMega328PU and a UART connector using a CT2102 breakout board. With the help of this site I created a simple IR sensor, now the problem is that in the Serial ...
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2answers
51 views

Recessed 12v Lighting - Transformer

I have wired an RV with 12avg romex. Incoming shore power is 110v, to a distribution panel/box. The lights that I want to use are recessed 12v lights, and the only ones I can find seem to have a ...
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1answer
97 views

Normally closed SSR won't work with grounding out a magneto's primary to ground

I've been trying to find a device that will ground out a magneto's coil (primary kill wire) in a normally closed state without using a mechanical relay because I want my circuit to be all solid state. ...
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1answer
62 views

Photo transistor in parallel

I'm a beginner and trying to figure out how this circuit works (its a simple circuit that glows an LED when dark) : https://www.youtube.com/watch?v=eIGWWKThprI&list=UUhtY6O8Ahw2cz05PS2GhUbg#t=65 ...
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1answer
63 views

Where is the bin code/label of LED?

Recently I have purchased 150 LEDs from Digi-Key and expected bin code/label of the batch to be on the package. But I can't find it? Where do I find bin code/label information?
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1answer
128 views

Controlling 90 LEDs using one WS2811

I wanted to build a circuit where i would be able to control 90 LED's using one WS2811 and have a total of 60 WS2811. In this circuit I hope to connect 30 LED's per channel, there is no need for me ...
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1answer
71 views

ATmega8 LED blinking project not working properly

I am making a simple project using ATmega8 microchip. I uploaded this code to the AVR: ...
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1answer
65 views

Connecting a 12V DC power adapter to Arduino [duplicate]

I'm working on a school project and I am a total beginner on this arduino stuff. So, I bought this led strip at IKEA and used this tutorial to connect it and controll it with my Arduino. The thing is ...