An LED is a light-emitting diode. Lighting an 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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2answers
12 views

Circuit for turn on a led when load connected

I'm searching for a circuit that turn on a led when the load is connected on its output, let's say for example a 5v power supply. I've seen few circuits that used two resistor in series with the ...
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1answer
49 views

Help in chosing Mosfet [on hold]

we have a circuit using a DAC http://www.analog.com/media/en/technical-documentation/data-sheets/AD5593R.pdf so basically the DAC output voltage is from 0 to 5V This DAC needs to finely control ...
6
votes
2answers
947 views

Why did my LED resistor burn while lighting four LEDs in series?

I have tried to create a circuit to switch a large 7-segment LED display (LDS-CD16RI) using a pair of MOSFETs, as follows: simulate this circuit – Schematic created using CircuitLab Here ...
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2answers
108 views

Decaying envelope when audio passes through diode

This is a basic question about passing AC (audio) signals through a diode. I'm trying to use an audio signal to power an LED (which in turn heat-shrinked to an LDR) in order to control the behaviour ...
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0answers
45 views

How can I under-drive bright LED strip lights *and* still dim them upstream?

So I'm using 7020 LED strip lights for under-cabinet lighting, and they will be connected (via a compatible power supply) to TRIAC wall switch dimmers (Insteon). There are other light fixtures on this ...
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1answer
74 views

Circuit Design for 6 LEDs flashing in sequence [on hold]

I am helping my son with his school project. He wants to design a circuit which has a on and off button and has 6 LEDS and each LED flashes for 20 seconds and stay on, and then the next LED will ...
0
votes
1answer
115 views

what dependence does the intensity of a normal LED(the one used for DIY projects) follow with respect to distance? [on hold]

What is the dependence of my led's output with respect to distance. I am guessing that since the LED inside the glass pane it is somewhat like a wire. Thus, it might follow inverse proportion with ...
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2answers
58 views

How much current do I need for a 5050 RGB strip? [on hold]

I want to use 5 meters 5050 RGB Waterproof 300 LED Strip + 20 Key Music IR Remote Controller Sensor. Is it okay if I use a 12V 6A Power Supply?
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4answers
87 views

Connect LED from audio output without it blinking?

I have a circuit in which I want a pre-built stereo amplifier kit (with + and - outputs for each speaker) to drive a speaker and an LED in parallel. The circuit works, however is there any way to stop ...
0
votes
1answer
87 views

Music reactive LEDs [closed]

I want to make a bigger project, but I have run in to a problem that I do not understand. I want to make an LED flash to music, for use in a bigger project. I have looked at about 20 different ...
0
votes
1answer
44 views

Relay circuit not switching as expected

I work on the book "Make - Electronics" doing some experiments. One of these is working with a relay. The simple schematic is this one: The circuit that I build works to 95%..... The left LED is ...
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3answers
89 views

Ceiling LED light emits very dim light when switch is off! [closed]

I have overhead ceiling LED light fixtures. When I turn on Main Switch of the house, I see the LED starts emitting very dim light ( have to look for a 3-4 second to perceive) even when LED's switch ...
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votes
1answer
42 views

Connecting Cathod Commond RGB Leds in parallel with arduino

I'm just starting with arduino, and want to light up 2 RGB leds (common cathode), and just think that the only thing I nedd was connecting them in parallel, no extra parts (my mistake), then I read ...
0
votes
1answer
58 views

Light dependent resistor (LDR) switched LED-circuit

NOTE! The LDR has a minimum val = 2kOhm and a max. val. = about 5 MOhm Im trying to build this circuit for my radio station. I would appreciate som help. Your general opinion about the ...
0
votes
1answer
53 views

Wiring a 5 Pin LED Switch

So my problem is that I need to wire up a 5 pin LED switch to a motor and a car battery. Seems easy enough... But I need the LED to be on at all times. That is the bit I'm getting stuck with. ...
0
votes
2answers
668 views

I don't understand the text about LED's type and power consumption

On my web-surfing, I found some information about LED's type and power consumption. I don't understand below (Red-lines.) Why 'common cathode' power consumption is lower than 'common anode'? Please ...
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votes
2answers
66 views

LEDs on 3.3V serial and sd card select lines

How would i go about connecting indicator LEDs to the serial lines from my MCU(a Parallax Propeller) to a MAX3232 and the chip select line for a SD card? I want the LEDs to light up when the lines are ...
0
votes
1answer
62 views

Motherboard RGB diode control and resistance?

I've recently acquired a new motherboard for my PC which features RGB strip control. That's well and good but I have particular need to control a single RGB diode with that same header. The issue I'...
0
votes
1answer
47 views

The right gauge wire for a 12v parallel wiring to LEDS and heat sink

enter image description here Hey guys would love your expertise on a project, I'm just a beginner on this stuff. I'm building an LED panel with a total wattage output of about 480W. My question ...
4
votes
0answers
49 views

Mosfet LED switch protection

I'm designing a Mosfet based switch that uses a low current reed switch to control either 24V or 12V LED strip lighting. Having some issues with the protection circuits. My specifications are as ...
0
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0answers
27 views

YX805 Datasheet Translation

The YX905 T0-94 package accepts a solar cell, charges a 1.5V AA battery and lights up an LED when it is dark. I don't know how the light detection functionality works -- maybe it is when the voltage ...
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0answers
21 views

I need to replace a few (blown) adapters 3.6v 0.85A to feed an LED Lamp [duplicate]

I need a few adapters; do I have to give priority on current, amps or power (3.06Wt)? I can find plenty 4.5v or 6v 0.8A; do I blow my LED lamp? (3.6 or 4.8Wt) for £3. I did found a Panasonic 3.6v/0....
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votes
2answers
47 views

LCD cbc016002A29 backlight resistor value

I'm trying to connect a cbc016002A29 LCD to 5V, and the tutorial I'm following says: Next we'll connect up the backlight for the LCD. Connect pin 16 to ground and pin 15 to +5V. On the vast ...
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1answer
63 views

Common Cathode vs. Common Anode (RGB LED) [closed]

"Power consumption of common cathode is lower than common anode about 30%" Is it right?
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2answers
83 views

Issues with NPN Transistors and RGB LEDs (Common Anode)

I have a question regarding the use of NPN transistors in an RGB LED (common anode) circuit connected to an Arduino Uno. I have spent the past several months developing LED color control software that ...
-1
votes
1answer
79 views

74HC595 LED sign [closed]

I'm new to electronics so I'm sorry if this sounds stupid. I recently created an LED sign consisting of 97 LED's on a piece of wood that all light up at the same time when I supply it with 3v. I have ...
0
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0answers
38 views

What do I need to do to stop a circuit a a giving voltage?

I made a battery charger for a emergency light back up (light is always on). I have a windmill/solar panel charging two battery's. I made it so when there is no power and one or the other batteries ...
2
votes
1answer
84 views

IR emitter in reverse bias? [closed]

What will happen if light is shown on IR LED (emitter) when it's in reverse bias condition?
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vote
2answers
108 views

How to ignore pulse in a circuit

I have a 12v cable that sometimes pass (75%on-25%off) and other times 100%on. What can I put on that cable so if the input is (75%on-25%off) then the output is 0v, and if the input is 100%on the ...
0
votes
3answers
165 views

Visible light communication

I am working on a project which uses visible light communication. The transmit side consists of mosfet irf J40 and bc547 transistors driving a 3W LED. At reciver side I am using a 5mm pin photo diode ...
5
votes
3answers
238 views

Why are 'modern' high-efficiency LEDs easier to damage than 'old' LEDs?

I have a few 'old time' LEDs from the late 80s and early 90s. The red and green 5mm LEDs (amber was a rarity, blue was 'impossible' back then). Not being very smart, I used to test them with a 9V ...
-1
votes
1answer
60 views

Powering an APA102 LED Light Strip

I am currently making a shopping list for an LED light strip (link) and I am getting 3m of it. Now, my main problem is powering that beast. By my calculations, (42W * 3m) / 5V = 25.2A, if that is ...
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2answers
42 views

Alkaline Battery for Boost converter for 1000ma current requirement?

I am working on a very small scale project that needs 300-600ma bursts at 5v for 10-20 seconds (a bank of LEDs) followed by a period of low power consumption (around 10ma for around an hour or so for ...
1
vote
1answer
61 views

Decreasing lumen and power usage

I have bought four of the very same led light bulbs two weeks ago. Their lightning characteristics appeared to be the same (brightness, angle, color). Two days ago I have realized that one of the ...
-1
votes
1answer
37 views

5 LED light display

I needed to have a simple circuit designed for a 5 LED light display ran off a 12 Volt battery, with an inline switch. The LED's are 3 volt, 20 ma. I needed to know what size battery I needed (...
0
votes
1answer
51 views

Using an arduino to read a 5050 LED signal

I have a project right now where I have access to a header to control standard 12v 5050 LED strips. What I'm trying to do is read that signal with an Arduino, and then use the values to control other ...
2
votes
4answers
484 views

Controlling color (and brightness) of RGB LED strip using one potentiometer

I'm trying to find a circuit that can manually adjust the color of a RGB led strip with one potentiometer. Ideally it would be a dual potentiometer to control brightness as well as color. But not ...
5
votes
2answers
177 views

Green LED: Forward Voltage

Yesterday in lab, we were asked why all of our green LED had large forward voltage than expected. We expected for the forward voltage to be at around 2.1V as according to hf=Egap=eV. Yet, we ...
6
votes
2answers
134 views

LEDs inside of solar-powered calculators

Why do a lot of solar-powered calculators contain red or infrared LEDs that are hidden from the user? So far I have only seen this in Texas Instruments calculators. Here are some examples of this in ...
-1
votes
2answers
52 views

I have a circuit with a 9V battery, followed by 3 10 ohm resistors, and an led all in series…?

simulate this circuit – Schematic created using CircuitLab I have a circuit with a 9V battery, followed by 3 10 ohm resistors, and an led all in series. The led has a forward voltage of 2.5V ...
3
votes
2answers
81 views

How to power a button's LED within a guitar?

I'm working on a guitar, and the plan is to use three latching push buttons so that each pickup can be turned on and off individually. I'm fairly confident that the following diagram should work for ...
0
votes
0answers
41 views

Bi-colour LED temperature indicator. Varying brightness. Thermistor as sensor

I want to make a temperature indicator using a bi-colour (reg/green) LED and a thermistor. GREEN should be fully on (20mA) at 25C (thermistor = 10K) and RED off (0mA), and at 100C (thermistor = 1K) ...
1
vote
2answers
74 views

Can I use a Triac dimmer circuit to control the brightness of an AC powered LED light strip? [closed]

I am using this Triac circuit to control the brightness of several incandescent lights. The circuit monitors the phase of the 120 volt wall current, then signals an Arduino when the phase crossed ...
1
vote
1answer
34 views

Inverter Generator Watt Question

I'm not sure how to search this so hopefully someone will answer. I'm rigging a floundering boat for my son and want to use LED light bars on the front and sides. I want to power then with an inverter ...
2
votes
1answer
110 views

Designing a PWM controlled power supply for a 30W RGB LED

I am building a DMX controlled light using an Arduino, but I am not sure which power supply I should use to power the LEDs which run at 36v (10 in series, 3 rows) 30W. The main problem is whether or ...
0
votes
0answers
53 views

Transistor behavior in Current Limiting Circuit

I have a circuit that I think will work, but I am worried that if I am overlooking or misunderstanding something about transistors in current limiting applications. The following is nothing original. ...
2
votes
4answers
497 views

Lower than 0.7-0.6V voltage drop on sillicon diodes

I am trying to understand how voltage drop happens. From what I know, there should be about 0.7-0.6V drop across a silicon diode. This is exactly what happens when I remove the LED from this circuit. ...
6
votes
2answers
947 views

Why are infrared LEDs used in optocouplers?

I read that optocouplers and optotriacs use infrared LEDs with infrared sensitive transistors. What is the idea behind using IR frequency but not visible light freq. LEDs inside a completely closed ...
0
votes
1answer
70 views

High power LED vs. standard LED

How do high power LEDs with forward current of 350mA compare to bright 5mm LEDs with forward current of 20mA? If forward voltage is the same (same color) does that mean light output of 17.5 of 5mm ...
4
votes
4answers
1k views

LED lamps keep glowing when dimmer is turned off

For starters, I am not electrically capable, so bear with me. But, I did read similar questions that did not address, as far as I could tell, what I see happening (they may have, but I was too ...