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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36 views

LED display problem [on hold]

we use LED video processor (LVP605S) with the connections of led display board wall. some problems are there in display. in display one meter are no display. only dark screen appeared.what can i ...
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2answers
51 views

Using 25 IR LEDs with Raspberry Pi and Transistor

Using a Raspberry Pi and 5V I want to use 25 IR LEDs (5mm LED, 940nm wavelength, 20 degree beam width, 100 mA continuous, 1000 mA pulse, Approx 1.6V forward voltage; ...
2
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1answer
45 views

LED's connected to a relay remain on?

I built a simple project with an Arduino board. I use the board to read analog input values from a rotation sensor (potentiometer), and use the values to determine which SSR relay on a module to turn ...
0
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0answers
59 views

Problem with PWM Output - PIC24F

The following is my code: ...
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0answers
26 views

Uneven distribution when using a mosfet for LED PWM drive [duplicate]

I'm using a set of NX3008NBK mosfets to drive a set of mid-range LEDs (~3.3V, ~20mA-60mA) with a microcontroller to apply PWM to control brightness. I am finding however, that the conversion between ...
3
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2answers
64 views

Component to detect the state of an external LED

I need to detect the state of an LED in a machine that I cannot connect to in any electrical way. So I would like to measure the light emitted from this LED. The conditions: The ambient lighting is ...
0
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1answer
72 views

wiring from car amplifier to leds syncing to bass

I have 12 V batteries, 2 1500-watt amps and 2 Ω each, and 2 subwoofers at 2 Ω each. I was planning on buying 4 blue 12 V led light strips that run at about 100mA each. I would like it to brighten/dim ...
1
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1answer
85 views

Why feedback is activating at more than 4V?

In this circuit: I don't get why the current start flowing from more than 4V. I thought was due to threshold, but the same happens with an NPN as M2 or using an BS170. With this last one, ...
0
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2answers
69 views

Use battery voltage rating or fully charged voltage?

I am using a 3.7V (18650) battery, but its fully charged voltage is 3.85V. When calculating a resister for an LED circuit, do I use the battery's voltage rating (3.7V) or the fully charged voltage ...
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1answer
72 views

Led circuit problem

So I'm hoping someone can help me understand my problem here! (Also sorry if this question has been asked before !) I've done a simple led circuit before , a switch battery pack connected to led ...
1
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1answer
134 views

Is this circuit block diagram correct?

I plan to build a flashlight powered by 360F 2.7V super capacitor (proposed to be charged to max 2.5V and discharged to min voltage of around 0.6V to increase capacitor life). The EMF generated by the ...
0
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1answer
80 views

Practicality of driving LEDs with high voltage?

After watching someone build a fairly wasteful project, I wondered if there was a better way. The LEDs are cheap chinese variety, with a forward voltage of around 34-36V @3A, and they throw off about ...
0
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1answer
61 views

Looking for 16 Segment LED/VFD Display with Comma, Decimal Point, and circle

I am building a KITT replica from the TV show Knight Rider. On his dash are 10 characters of 16 segment LED's that have a decimal point and comma. In addition to that, there is a circle beneath each ...
1
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2answers
37 views

Is a NRTL / UL mark required for battery powered products?

We have a small 12VDC battery powered projector that uses a 5 watt LED to project an image through a transparency onto a wall Electrically it is equivalent to a flashlight. Does this type of product ...
0
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0answers
52 views

X-rated capacitors in parallel

I want to build a transformer-less power supply (capacitive) to drive few 0.5W power LEDs from mains supply (230V). The 1uf X-rated capacitors I have are not good enough to drive them to full ...
0
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1answer
77 views

How to make this I2C OLED screen work? (probably SH1106)

I have just received this screen: link but unfortunately it's different then other showed in reviews. That's my version link It's probably based on SH1106 but I can't make it work. I have tried few ...
0
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1answer
64 views

What's the difference between IC 74HC04 and IC 74AC04PC?

I am trying to make a simple logic gate simulation for which I require the former IC but I could only procure the latter. Will it still work?
1
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1answer
44 views

input amps for 10 amp power supply

I am looking at installing some LED lighting which requires a 12v DC 10 amp power supply. The question which I cant seem to find an answer for is this... I live in the UK which uses a nominal 240 v ...
0
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1answer
33 views

Calibrating buck LED driver by altering Vsens

Many switch mode buck LED drivers use a current mode scheme with a sense resistor back to a Vsens or Current Sense input on the chip. A good example is the LM3404. Here's the typical use circuit: I ...
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0answers
26 views

RGB LED BCP wire [closed]

Ok so I know how rgb light strips like this one work but I am not sure how the ones like this work because there so close together. What bcp would i need? How would i even start making this?
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1answer
76 views

PWM with MOSFet- make it linear

there maybe wrong assumption in my question , so forgive me, i am here to learn . So controlling a light(LED) with MCU that outputs PWM, into a MOSFET N-CHANNEL, as described in this little image: ...
0
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5answers
193 views

How to drive 30 LEDs with a smaller amount of pins?

We have 30 LEDs in a row, and we want to turn them on left to right. However there are way to many for the Arduino to have each one on a different pin. Is there an IC that can take a binary output, ...
0
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3answers
96 views

Why LED reversed bias voltage cannot be measured?

As I have just found out, typical LED does not behave similarly to standard diode when measuring reversed bias voltage. On typical diode, you can measure reverse bias voltage about .3 to .6V, but not ...
0
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0answers
54 views

Light powered by rocking kinetic device

I want to know if i can power a lower power light by simply rocking it. The light only needs to be on while its moving so should only require a small amount of power. I have included a picture that ...
4
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1answer
64 views

SMD LED polarity marking

SMD LEDs normally have some kind of marking like the following image from here indicates: The site states The CATHODE lead is always the lead to be identified with ALL LEDs, including ...
0
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1answer
37 views

5x3w led lamps power supply

I am new to this site and a little desperate too as I am no electrician. I purchased some led lamps (3w, 12V) to replace a series of G4 20w lamps I run in my household. Since the wiring is in the wall ...
0
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3answers
57 views

how to reduce the brightness of the usb led light? [closed]

I want to play computer in my bed without turning on the light, so I purchased this usb led light, the problem is the brightness is too strong, my eyes feel uncomfortable , so can you help to figure ...
0
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3answers
126 views

problem regarding AND gate using diode

I am currently having problem understanding the basic circuitry of AND gate using diodes and how it works. As we know, the basic AND gate circuitry using two diodes is something like this. And we ...
3
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2answers
369 views

Does a 1 watt 660nm LED put out more radiant flux than a 1 watt 630nm LED?

Given two LED chips consuming same or very similar amounts of DC power, One emitting light peaking at 630nm, The other at 660nm, In terms of output of (but light irrelevant to the sensitivity of ...
0
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0answers
53 views

How to increase number of LED blocks in a moving LED display

I have been working on a project where I have to make an 80x20 sized moving LED display. I'm using a decade counter to shift the characters being displayed. I want to know, in the programming ...
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0answers
55 views

High power LED driver

I want to drive 5 (100 watt LEDs) cool white, but only at half power a total of 250 watts. The spec of each chip is 32-34 volts DC @ 3.5 Amps. Ideally I would like to drive them all from one power ...
0
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1answer
139 views

Is it safe to parallel connect components to a single to a 12v DC PSU?

Prerequisite: For a home-decor project, we wish to work with different LED strips and even a larger LED chip as a central lighting source by attaching everything to a powerful, high quality 12v CC/CV ...
0
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3answers
57 views

How to adjust red brightness on MAX7219 with RGB LED

I want to use MAX7219 (datasheet) to control bunch of RGB LEDs. With common anode LEDs I should be able to use up to 16 3-color bulbs in following configuration: simulate this circuit – ...
0
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1answer
88 views

How does underdriving a powerful (eg. 50w, 100w) LED chip work?

My question concerns under driving an LED chip. Unlike quality brand chips (Bridgelux, Cree), in my experience, under-driving non-brand ones make things more long lasting and favorable. Using the ...
0
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1answer
63 views

Driving an infrared LED from a coin cell

I am designing a remote-control type IR transmitter that will be powered by a coin cell battery (i.e. CR2032) and commanded by a microcontroller. The LED is pulsed at around 40kHz. How can I ensure ...
0
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2answers
49 views

Best resistance for RED/BLUE 3 lead LED

I have a project where a PCB has been manufactured with an error, where a 3 lead BI color LED (red/blue) has a single resistor to limit the current for both colors. I can fix this by hacking apart the ...
0
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0answers
20 views

Arduino Uno PWM [migrated]

My scheme is very basic: I use RGB LED with Arduino Uno. 5v is connected to anode, and pins 9-11 are connected to cathodes. When using following sketch, my LED is producing white colour, which red, ...
2
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2answers
367 views

How does a solar garden LED work with just 1 AAA battery?

I am converting some solar LED garden lights to emit infrared light for a raspberry pi critter camera to see what kind of wildlife trifles through my garbage at night. I just have one question. ...
1
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2answers
64 views

RGB LED powered with USB Questions

I have a project in mind using an RGB LED (here: http://amzn.com/B007RO9X82). I would like it to be powered by USB. Since the LED is rated at 3.0-3.6V, I understand I'd need a resistor. What ...
1
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2answers
61 views

compensate for missing leds

I bought a small DIY infrared emitter today, but two of the LED's are missing. The data sheet for the LED's is also missing. The schematic is like this (a bit bigger): Power source is 12V. There ...
0
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3answers
72 views

Transistor with different voltage in colector and base

I have a small LED of 5mm and an arduino powered by 9V. When I connect the LED to Vin (9V) using a 330 ohm resistor the LED brights very high. When I connect the LED to 5V (from arduino) using a 330 ...
0
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1answer
38 views

LED Backlight driver output current

Our LCD has 10 series white LEDs for backlight with total Vf of 15V and current of 40ma. The backlight circuit is designed with SC4509. As per the datasheet its recommended output voltage is 20V and ...
0
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2answers
56 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 ...
0
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1answer
50 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 ...
0
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1answer
34 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 ...
1
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2answers
194 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 ...
1
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1answer
97 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 ...
0
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1answer
68 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 ...
0
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2answers
45 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 ...
0
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4answers
85 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 ...