hybridfree/eevblog-posts huggingface dataset:
led brightness control (using PWM) - Page 1
Forum section: electronics / projects

author: Farouk1920
author_rank: Newbie
timestamp: December 05, 2016, 09:28:26 am
content: Hello friends, my semester project in microprocessors course is an automatic control of a power led according to the light of day. it's required to use an LDR as a light sensor, a 16F877a pic microcontroller . in the class we still didn't take the PWM lesson but i don't have much time to do the project. I took a look at the internet and i understand its logic but i failed to write the xc8 for a pw module related to the analog input of the ldr.can someone help me

author: Zero999
author_rank: Super Contributor
timestamp: December 05, 2016, 10:42:26 am
content: Please post the code and the schematic.It sounds quite straightforward, other than I don't have much experience with C. I'd use assembler for this and if I wanted a challange, I'd use an old MCU with no PWM module, such as the 16F505 and do the PWM in software.

author: MrMetthew
author_rank: Regular Contributor
timestamp: December 05, 2016, 12:21:02 pm
content: For this simple project it would probably even be easier to write the pwm yoursels instead of figuring out how to use the pwm modulle. Anyway I'm assuming your a beginner in the world of micro controllers. I can give you a piece of advice that will really help you with reaching your goal. Read the datasheet, read the datasheet again and then read it some more. Trust me PIC's have really good datasheets, but can be cumbersome to read for a beginner. You will need to figure out the ADC to measure the ldr sensor and the pwm modulle, and also need to add some very minimal "glue" C code. You can use of of the timer blocks as pwm modulle, I doubt they will actually be called PWM modulle in the datasheet.If you're stuck with your code, just post it here!

author: steaky1212
author_rank: Regular Contributor
timestamp: December 06, 2016, 03:04:26 pm
content: Have you assigned a timer to the PWM module?

author: xack
author_rank: Newbie
timestamp: December 06, 2016, 09:37:34 pm
content: Best would be if you do it like MrMetthew said.But if you need a quick (and i think easy) tutorial, have a look at this Instructable (btw. first google result):http://www.instructables.com/id/Generating-50Hz-PWM-Using-PIC16F877A/?ALLSTEPS
LED clock of a different kind - Page 1
Forum section: electronics / projects

author: micha1102b
author_rank: Contributor
timestamp: June 06, 2021, 12:30:29 pm
content: Hi there,after a long time I've finished a new, little weird, LED clock project.You can watch it in action here:https://youtu.be/TAu93EqjSwkThe real challenge was the software (9 pins only for 60 standard LED charlieplexed, special pulse modulation for individual LED dimming, 4k words for flash only).Any improvements, suggestions and new ideas are highly appreciated!regardsMicha

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 07, 2021, 04:11:38 am
content: I like it. Why is the name of your second picture in German? "Finished, soldered, red"

author: micha1102b
author_rank: Contributor
timestamp: June 07, 2021, 03:16:27 pm
content: simple answer: I am Germanbest regards

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 07, 2021, 04:02:01 pm
content: Das macht Sinn.

author: micha1102b
author_rank: Contributor
timestamp: June 07, 2021, 04:14:03 pm
content: Dein username laesst ja auch aehnliches vermuten

author: rvalente
author_rank: Frequent Contributor
timestamp: June 08, 2021, 01:39:53 pm
content: Congrats, really well made.How many bytes of flash had left?What capture softwate you used to draw the schematics? Looks soo elektor electronics to me, vintage!

author: coromonadalix
author_rank: Super Contributor
timestamp: June 08, 2021, 02:24:56 pm
content: Do the leds illumination(s) bleed on the others ??

author: micha1102b
author_rank: Contributor
timestamp: June 09, 2021, 09:39:58 am
content: Quote from: rvalente on June 08, 2021, 01:39:53 pmExactly 4 bytes left. I had to code everything from scratch, since no lib is there for such a special application.Schematic was drawn with a (vintage) version of eagle.

author: micha1102b
author_rank: Contributor
timestamp: June 09, 2021, 09:48:21 am
content: Quote from: coromonadalix on June 08, 2021, 02:24:56 pmNo bleeding at all. Circuits with charlieplexing allow to light up no more than ONE led at a time.To avoid any possible bleeding I inserted a dark cycle after each lighting on cycle.Of course, extra bright LED should be used to get reasonable brightness.p.s. : Bleeding becomes a huge problem if flux or other dirt is left on the PCB. Even stray currents in microAmpere range would light up unwanted other LEDs to a disturbing level.
LED Clock Project - Page 1
Forum section: electronics / projects

author: jbix
author_rank: Newbie
timestamp: January 15, 2016, 08:03:52 pm
content: It's been quite some time, working on this off-and-on. But the (hopefully) final prototype board just arrived. It's a 12-inch wall-clock with three rings of 60 LED's. I'm hoping to offer it as an assembled, working clock, as well as in kit form. And, yes, it will be open source. Forgot to mention it also has a 6-digit, 7-segment digital readout in the center for times when you don't feel like translating the rings to time. The center readout can be toggled on/off. It also has three different display modes: Progressive fill-up, fill-down and "classic" (only one LED active per unit of time). In case it isn't obvious, the outer ring (red) is seconds, middle (green) is minutes and inner (blue) is hours. It's been a fun project, full of learning. Inspiration to go for it comes from places like this forum, and guys like Dave and Ben Heck on YouTube.
LED control options - Page 1
Forum section: electronics / projects

author: danners430
author_rank: Regular Contributor
timestamp: January 31, 2019, 11:52:09 am
content: Morning guys,Following on from my last post around the WS2811 drivers, I've been having a further think about the best way to control the LEDs on my control panel... But I've done the usual, and only gone and confuzzled myself!! Would you guys be able to offer your opinions on what you reckon would be decent bets for control options?A little information around the panel:Consists of 40x40mm "tiles", made up of 6 standardised PCBsUp to 3 RGB LEDs on any one tile at any time, although some PCB designs have space for moreTwo types of "special" tile - one 80x40mm tile with 3x 8x8 LED matrices for 4-digit alphanumeric display, and one 40x80mm tile with a unique tile designapprox. 300-350 RGB LEDs total, not including the 8x8 matricesThe options I've looked at so far are the WS2811/WS2812, and some matrix drivers... does anyone have any other suggestions? I'm ideally wanting to keep physical wiring to a minimum, to keep the inside of the panel reasonably tidy
LED Cube Verticle Drawing Failure - Page 1
Forum section: electronics / projects

author: bendepd
author_rank: Newbie
timestamp: June 10, 2021, 11:46:47 pm
content: Hi everyone,I successfully completed my 8x8x8 LED cube (by CHR) (https://www.instructables.com/Led-Cube-8x8x8/) some months ago. The vague idea is that an ATMEGA32 sends data to shift registers which then store it and choose which LEDs to give the most percentage on time in the PWM signal sent to the column (apologies for absolutely botching this).Recently decided I wanted to make it more portable by simply adding a 3xAA battery pack to power it. However, in the process of completing that (taking the boards out of the casing and adding in the battery pack to the power lines), my cube has now started running into issues. The issues may have occurred before this changeover but not that I was aware of. I have attached schematics of the boards below.In particular, the cube appears to struggle to draw patterns upwards or downwards when lighting up more than a few columns. Roughly 90% of the animations from CHR (original instructable poster) and SuperTech-IT (a second 8x8x8 LED cube instructable posterhttps://www.instructables.com/CHRs-8X8X8-LED-Cube-Revisited-with-improvements/) work flawlessly.https://youtu.be/ek0a47CwT9EThe first video shows a diagnostic test. It shows that each column can be lit up without issue. The diagnostic is then meant to light up each and every LED one by one from the bottom. However, mine instead appears to light up each layer (via each LED) one by one, but the last verticle plane always fails to do so. In the end the whole cube is meant to be lit.https://youtu.be/GVRopbZ86KYIn the second video, it shows more clearly the issue my cube has with lighting up each of the horizontal layers one by one. This is shown when it looks like a single column lights up dimly. It also shows how other (potentially less power consuming) animations work flawlessly.These tests make me vaguely think it could be something to do with the transistor layer select array however I am not sure (the instructable used PN2222 transistors as it was what they had laying around, I followed this as I too had them lying around). Any advice would be beyond appreciated.Thanks

author: jmelson
author_rank: Super Contributor
timestamp: June 11, 2021, 12:22:36 am
content: Are you sure your AA cells can deliver enough current to light the LEDs without the voltage sagging? That would be my first thought. When the voltage sags under load, the micro may reset or just malfunction.Jon

author: bendepd
author_rank: Newbie
timestamp: June 11, 2021, 12:55:41 am
content: Hi Jon,Sorry I should have mentioned that I have also tested it with my ATX computer bench power supply (provides ~5.5V with 12A+ max current) and the same issue occurs.

author: bendepd
author_rank: Newbie
timestamp: June 11, 2021, 11:12:07 pm
content: I apologise to all, I realised the video links were broken. They are now updated!
Led curcuit - Page 1
Forum section: electronics / projects

author: markus1234
author_rank: Newbie
timestamp: September 19, 2015, 11:40:11 am
content: Hi,i wathed eevblog 708 where dave debunks some free energy curcuit.He says that it's actuall "piss poor" and only 50% efficient.So for learning porpuse, what aould be the (nearly) ideal led curcuit to power 23 leds? ( in terms of efficiency)thanks in advance,markus
LED Dance pattern generation - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: April 17, 2018, 02:43:06 pm
content: Hi,I'm doing some cool LED effects, I have 3 RGB led's each with a 16bit color depth PWM, I have made some animations on them, but the problem is making long patterns, Do we have some software to generate dance patterns for led's?Here is the array for blinking ledsCode:const uint16_t dance_pattern={// B_LED3 R_LED3 G_LED3 G_LED2 R_LED2 B_LED2 G_LED1 R_LED1 B_LED1{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x000F},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00FF},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0FFF},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x000F, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00FF, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0FFF, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x000F, 0x0000, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00FF, 0x0000, 0x0000},{0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0FFF, 0x0000, 0x0000},};Also you can see some video in this linkhttps://youtu.be/CdbzzwZ1hvU
LED Desktop Magnifying Lamp repair - Page 1
Forum section: electronics / projects

author: jonovid
author_rank: Super Contributor
timestamp: April 28, 2017, 05:53:05 am
content: LED desktop lamp with a diffusion lens It features 18 super bright LEDs in a ring, if you see this design for sale.it has a flexible goose neck for directional light, an integrated switch on the base, 2x magnification,an AC to 5 volt 1 amp DC adapter and battery provision (3 x AAA batteries, not included).The base measures 15 cm in diameter and the lamp, fully extended, is 49 cm high. comes in black or white.in an example of poor design the 18 LED resistors have values set for 4 volts 42 ohm - for the 3 x AAA batteries.but not for the 5 volt 1 amp DC - AC plugpack adaptor. so the Desktop Magnifying Lamp will fail in less then 200 hrs.at 800ma the 3 x AAA batteries will be dead in no time. so the AC plugpack adaptor is used.here is my Desktop Magnifying Lamp repair useing warm white smd .5 watt LEDs. and a two diode voltage drop mod on the power input jack.
LED Display Driver w/o Resistors & LED Display Longevity - Page 1
Forum section: electronics / projects

author: Infrared_Fred
author_rank: Regular Contributor
timestamp: October 30, 2020, 02:48:56 pm
content: Hello! This is a repost from a different forum where I was suggested to post here."I have this circuit in consideration for a LED display project and I was wondering if a circuit like this would be likely to reduce the longevity of the LED's lifespan, assuming the PWM frequency is high enough to not exceed the thermal mass of the LED and overheat it directly with high peak currents. Attached is the schematic in .pdf format. As the schematic generally suggest I have not ironed out every circuit detail, nor am I necessarily definite on a single specific circuit element."Any thoughts on the circuit is welcome.Thanks for any help!https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/v.1.0-ULN2003-74HC04-TLC555-PWM-LED-Display-Driver.pdff

author: TomS_
author_rank: Frequent Contributor
timestamp: October 30, 2020, 08:38:11 pm
content: Is something like a TLC5916 LED driver out of the question? It only requires 1 resistor to set the current for all of its channels.

author: Infrared_Fred
author_rank: Regular Contributor
timestamp: October 30, 2020, 10:51:54 pm
content: I could use the TLC5916 for microcontroller projects (it has a serial input), but I am mainly interested in building this circuit because it is simple for non-microcontroller input a.k.a. counters, and I already have all the parts on hand.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: November 02, 2020, 03:24:01 am
content: You are using the wrong solution. Different numbers will light up with different brightness because several segments will be turned on simultaneously in parralel. You must limit the current of each segment separately. To do this, it is enough to use conventional current-limiting resistors and this indicator will please even your granddaughters.If you don't like resistors, you can use special current limiters for LEDs: NSI50005YT1G, NSI50010YT1G.
LED drive spec's - Page 1
Forum section: electronics / projects

author: viji_rookie
author_rank: Contributor
timestamp: June 14, 2016, 11:47:45 am
content: Is it Safe to drive LED(lets say PLCC package) with >30mA and >2volts ? O0

author: Kjelt
author_rank: Super Contributor
timestamp: June 14, 2016, 01:35:03 pm
content: I don't understand your question?There are for instance white leds that have a typical voltage drop of 3-3.1V's and some white smd led's are made for 150mA nominal etc.So what is the partnumber and what are the datasheet nominal operating values ?

author: Fungus
author_rank: Super Contributor
timestamp: June 14, 2016, 01:38:44 pm
content: Quote from: viji_rookie on June 14, 2016, 11:47:45 amHow long is a piece of string?Read the datasheet for the specific LED you're using.

author: viji_rookie
author_rank: Contributor
timestamp: June 14, 2016, 06:30:23 pm
content: Quote from: Kjelt on June 14, 2016, 01:35:03 pmI forgot to mention this;I'm using Kingright AA3528EC to indicate the power up, datasheets says Absolute ratings 30mA, which is my ckt drive current, instead do i have to derate my current to match the nominal ratings of this LED and drive it ?

author: georges80
author_rank: Frequent Contributor
timestamp: June 14, 2016, 06:58:32 pm
content: What is the actual 'driver' to this LED in your design? -> schematic would be worth 1000's of words...By checking my crystal ball (since you've provided no actual information about your design) I'd suggest an appropriately sized series resistor will likely resolve your problem.cheers,george.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 14, 2016, 09:02:30 pm
content: For the most part 'absolute maximum ratings' are there to show the 'maximum' continuous current you should ever apply under ideal conditions - which are stated in the datasheet. There is rarely a need to approach this limit as most low power (read: not power) LED's are driven anywhere from 5-15mA. And the simplest 'drive' method is a current limiting resistor with the value:(drive voltage - LED forward voltage)/current.You can probably go over the rated maximum for brief periods - often IR remotes do this as they are generally modulated at <50% duty, and operated at very low duty, and need to be 'bright' for range.But without any information - I would say driving a PLCC2 LED at 30mA would significantly shorten its life if operated continuously, and isn't necessary.
LED Driver as MCU Power Supply - Page 1
Forum section: electronics / projects

author: mister_jay
author_rank: Newbie
timestamp: August 03, 2022, 02:58:03 pm
content: I recently found this IXVS IC MXHV9910 on Mouser (Here's the datasheet:https://www.mouser.com/datasheet/2/240/MXHV9910-1548173.pdf) well aware that it is a constant current driver IC. However - the broad input range is really appealing to me. Now i was wondering if there is a way of powering a Load that requires 3V3 @ ~500mA with it. The current draw is varies widely on which peripheral is enabled.500mA is the maximum current draw expected from the device.I'd appreciate your help.

author: John B
author_rank: Frequent Contributor
timestamp: August 03, 2022, 07:36:12 pm
content: The wide input range is for the ICs internal voltage reference, control circuitry and gate driver which in total amounts to a few mA tops in the worst case. It's a linear regulator, so when running from a mains voltage application you still need to consider the power dissipation even at a couple of mA if you are dropping hundreds of volts.What is your upper input voltage? There's a few inexpensive buck ICs in the 500-800mA range that will go up to 80V inputs.These HV9910 type LED drivers are pretty simple for a LED driver. Even if you could produce a CV output with extra circuitry, the output waveform will probably be noisy and your output voltage will have a ground offset as it's a lowside driver.
105+ LED Driver IC Identification - Page 1
Forum section: electronics / projects

author: aggo_ee
author_rank: Newbie
timestamp: August 20, 2024, 03:54:37 am
content: I am trying to identify an LED driver IC that has had the markings sanded off. It is a L/TQFP-128 package as far as I can tell and from testing with a multimeter each pin is driving a string of 3 or 4 LEDs (depending on colour/forward voltage) and sinking current to turn them on. There are 42 pixels on the PCB with each pixel having 5 different colours for a total of 210 strings of LEDs each IC controlling 105 strings. The single panel has two of these unknown ICs that based on the silkscreen are using a clock, data, latch connection with a series data connection akin to a shift register. I have not had any luck finding any led drivers or shift registers with current control similar to this TB62D612FTG and suspected it may be a microcontroller although assuming each pixel has only one colour active at a time it would still need to be sinking 21 X 20mA (measured) for a total of 420mA which seems far higher than the total current sinking capability of a standard microcontroller.

author: thm_w
author_rank: Super Contributor
timestamp: August 21, 2024, 12:10:00 am
content: If its 3 or 4 LEDs then the open circuit voltage is probably too high for a MCU as well.There are tons of these type of ICs on LCSC, but, nothing close to 128 pins.https://www.lcsc.com/products/LED-Drivers_583.htmlMaybe post a photo.

author: aggo_ee
author_rank: Newbie
timestamp: August 21, 2024, 01:55:55 am
content: Unforunately I no longer have the PCB but for my own knowledge wanted to figure out the method they could be using to control 105 strings of LEDs with a single IC. I have some notes of the package pin connections to ground, latch, data etc however even finding the correct topology in a matching package seems to be difficult. Unless I'm missing something the MCU also wouldn't be able to control the current as it would just sink directly to ground.
LED Driver query and measuring instruments - Page 1
Forum section: electronics / projects

author: talespin
author_rank: Newbie
timestamp: January 05, 2025, 06:24:47 am
content: Hi Everyone,I have a LED Driver/DC Voltage boost question.Problem:----------------I have a LED projector that has a driver board which powers three LED's (RGB)LED run at less than 5V(all three have different forward voltage)LED Datasheet :https://download.luminus.com/datasheets/Luminus_PT-120_Datasheet.pdfLED can be run at lower continuous current - 27APulsed higher current.Frequency = 240Hz and Duty Cycle = 70%I need to replace these LED's with a different LED for higher brightness.Normally one would use a different/New LED driver board matching the new LED's, but the LED driver board in Projector has connection to other circuits which are very complex and OEM specific. I only want to boost voltage and limit current without changing frequency and duty cycle.Frequency and Duty cycle to be controlled by source(Driver board).Question1:Is it possible to convert 5V/27A-30A to 21V/8A without changing frequency and duty cycle (if LED is being pulsed rather than continuous) by taking the output (2 wire) from LED driver board and boosting the voltage and limiting current to 8A without changing the frequency and duty cycle?I know it is possible through DC-DC boost circuits and current limiting circuit but what I am not sure is if they will change the frequency and duty cycle.If yes, please provide general guidance on how I can achieve this.Question2:I need to monitor/measure the output of LED driver board, measure frequency (In this case around 240Hz) and duty cycle.Can you please recommend a good quality affordable scope and brand for beginner.What frequency range should I look for?I am going through scope training link on this forum.Thank youHappy New Year
LED driver to drive 8 LEDs with 8 GPIOs - Page 1
Forum section: electronics / projects

author: muthukural001
author_rank: Regular Contributor
timestamp: May 03, 2020, 09:49:36 am
content: Hi,I need to drive 8 LEDs with 8 GPIOs (Each GPIO for Each LEDs. I thought of having 8 transistor where GPIOs is connectied at the base of the transistor to drive these LEDs. Instead of having 8 transistors, there is any single chip solution to do this?...Please suggest.Thanks and Regards,Muthu

author: greenpossum
author_rank: Frequent Contributor
timestamp: May 03, 2020, 10:16:06 am
content: You can use a 74HC595 to drive the LEDs and clock in the data serially which means you can use 3 or 4 GPIO outputs. See this project which drives up to 16 LEDs. You only need to implement half of it:https://hackaday.io/project/168654-an-uninnovative-linear-led-display

author: Ian.M
author_rank: Super Contributor
timestamp: May 03, 2020, 10:27:33 am
content: Insufficient data:LED Vf?Desired LED If?Supply voltage?Logic Vcc?

author: ebclr
author_rank: Super Contributor
timestamp: May 05, 2020, 07:02:04 pm
content: A simple 330 Ohm resistor will do the Job, in most CPU's. without any transistor,

author: spudboy488
author_rank: Regular Contributor
timestamp: May 06, 2020, 11:42:13 am
content: As others have said, not enough information. The method will be different depending on the specifications of the components used.Generally:The CPU can directly drive the LED anode with a current limiting resistor depending on the CPU pin current spec and overall CPU current spec.There are instances where the CPU can sink more current than it can drive. In these cases, the CPU can directly sink the LED cathode with a current limiting resistor depending on the CPU pin current spec and overall CPU current spec.The CPU can drive a ULN2803 (or equivalent) 8 channel transistor array which can sink the LED cathode with a current limiting resistor.You can use port expanders, shift registers, etc. but those would still fall under the same rules as directly driving with the CPU.More info would make it easier to answer.
LED Drivers - Page 1
Forum section: electronics / projects

author: CM800
author_rank: Frequent Contributor
timestamp: December 09, 2019, 02:42:09 pm
content: Hi All,I've got a project for seven segment displays7 segments of 16 LEDs (each one is a 5x5mm, 60mA LED @ 3-3.6VF)Using a 24V supply for the system, what would be the recommended method of driving these sets of 16 LEDs?I was thinking 4S4P for each segment, giving 14.4V @ 60mA per chain, then 240mA per segment.Could equally go up to 36V and go for 8S2P giving 28.2V @ 60mA per chain then 120mA per segment.Any solutions people have had with good success? Minimum components would be nice due to hand assembly (or maybe that new JLC PCB assembly service...)
LED Filament Boost driver chip. - Page 1
Forum section: electronics / projects

author: wemme
author_rank: Regular Contributor
timestamp: August 14, 2015, 02:37:38 am
content: Hello.I am looking at using some discrete LED Filaments for a custom lighting design which will be powered from 12 to 30 VdcThese have a forward voltage requirement of 75Vdc which is outside the drive range of most LED driver chips.Has anyone come across a suitable driver chip ??I have had a look at TI and Linear tech so far and nothing has come up worth while.RegardsBart

author: ajb
author_rank: Super Contributor
timestamp: August 14, 2015, 03:22:36 am
content: A better bet may be to use a boost converter with separate low-side LED drivers. There are some LED driver ICs that are actually designed to be used with an external switching converter; they have an analog output intended to driver the converter's feedback node to trim the voltage up or down to maximize efficiency. The Atmel MSL2041 is one such, but there are others out there.

author: wemme
author_rank: Regular Contributor
timestamp: August 14, 2015, 03:47:35 am
content: Thanks for the replyI was looking at the LTC3805-5 as a boost converter and then just tweak the voltage but that would be better.

author: wemme
author_rank: Regular Contributor
timestamp: August 14, 2015, 04:14:07 am
content: Just found these guys which will all do the boost and current control.AP306, TPS61196, LT3755 and RT8475.

author: Zero999
author_rank: Super Contributor
timestamp: August 14, 2015, 07:53:55 am
content: Quote from: wemme on August 14, 2015, 03:47:35 amDo you need to switch the LEDs individually? If not then you could use the LTC3805-5 and take the feedback from a current sense resistor, rather than a potential divider.If you're using an MCU to switch the LEDs then you could use a constant voltage supply and add an emitter resistor to each switching transistor to form a constant current sink.
LED flasher board - Page 1
Forum section: electronics / projects

author: lilshawn
author_rank: Regular Contributor
timestamp: June 07, 2018, 07:02:51 pm
content: this utter pile of trash is expensive as hell ( about $90 bucks each for a 1.6 x 3.7cm board) and is badly designed to boot. 3 of the 4 boards I have, have failed. I'd like to redesign these to be a little better...use more common LED's instead of the fancy special LED's spec'd (something like a 5050) and improve the switching circuit (which seems to me, be the main failure mode) with maybe some kind of single MOSFET.1 - 20vdc2 - N/C (KEY)3 - data4 - GroundEDIT: signal "trigger" voltage is about +1.5 to +1.9 vDCdata signal turns on LED's (LED's only on for a fraction of a second)I'd like to spin off 10 or so boards at one of those cheap chinese prototyping places to replace these, but not sure where to start fixing this. I mean I have this schematic could make a pile boards for cheaper than the one for 90 bucks, but still end up with the same shitshow later on.any tips would be greatly appreciated.thanks in advance!

author: ajukarandikar11
author_rank: Newbie
timestamp: June 08, 2018, 11:07:55 am
content: Hello,Have a look at the link below:https://arduinoelectronics.wordpress.com/tag/lm317/Looking at the limit resistor values, your current is about 1.06A which isabovethe rating of your LEDs.

author: Gibson486
author_rank: Frequent Contributor
timestamp: June 08, 2018, 01:00:50 pm
content: Quote from: ajukarandikar11 on June 08, 2018, 11:07:55 amI am willing to bet it is done on purpose. With pulsing LEDs, you can pulse them, but since you pulse them, they do not achieve steady state luminescence since you are effectively PWMing it. To alleviate that, you run them at higher currents than speced. You can get away with it as long as you obey what the max average current is.I have never used an LM317 like that before. However, from my experience, when you use bjts, you need to account for variations in beta when using with anything involving a current source. It looks like this tries to achieve it feedback by getting something back at the collector, but you still need to take care of the be junction. I may be wrong, so maybe i need enlightenment.but yeah, if you are going to redesign, they make ICs for this very purpose.Something like this...https://www.diodes.com/assets/Datasheets/AL8861.pdfedit:I just saw you +1.5 to +1.9 vDC requirement. That makes those ICs harder to use, so you may want to scratch that.Ahhh...I read the link. I see how it works....He is just using the bjts as switches to turn it on and off.
LED Flasher Circuit - Page 1
Forum section: electronics / projects

author: ksb
author_rank: Contributor
timestamp: March 04, 2020, 03:31:10 pm
content: Hi,Can someone guide me how to design LED Flasher using BD139 which all the LEDs (max 8 LEDs) must connected in series? What i have found in the net is the LEDs connected in parallel. See attachment.

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2020, 03:44:34 pm
content: The circuit requires a high enough voltage for the BJT to undergo avalanche breakdown and start conducting. The LEDs all drop between 1.6V and 3V and with them all connected in series the voltage is too low for that to ever happen.See the thread linked below for more information about how the circuit works.https://www.eevblog.com/forum/beginners/why-does-this-led-blink/

author: rvalente
author_rank: Frequent Contributor
timestamp: March 04, 2020, 06:21:44 pm
content: Do you really need to use just one transistor? Make it two, much more reliable.This flasher is more of a prank than a circuit itself
LED flashlight PWM in the rain - Page 1
Forum section: electronics / projects

author: snarkysparky
author_rank: Frequent Contributor
timestamp: January 13, 2017, 04:38:07 am
content: I just happened to point my LED flashlight into the rain last night and saw what only a serious geek would get excited about. And since that covers present company I will share.What I observed was linear streaks with on and off times consistent with the duty cycle.Need to figure a way to photograph it.

author: Zero999
author_rank: Super Contributor
timestamp: January 13, 2017, 09:51:16 am
content: Try looking at a spinning wheel with it.

author: amyk
author_rank: Super Contributor
timestamp: January 13, 2017, 12:01:51 pm
content: Quote from: snarkysparky on January 13, 2017, 04:38:07 amLong exposure.
LED footprint - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 29, 2017, 03:43:56 am
content: I've been tasked with improving a layout that uses these LEDshttp://www.digikey.ca/product-detail/en/kingbright/APHB1608ZGSURKC/754-1650-2-ND/2683994My boss told me to use a much bigger pad for each pin for manual rework. OK.I want to use a larger copper pad, but with a solder paste blob the same size as before, and with a soldermask dam to keep the solder in place, yet provide thermal contact for the soldering iron.How about the attached footprint? It's not to scale, just something I threw together.The yellow is the LED, the large gray rectangles are the copper, the green is the dam, and the blue is roughly where the solderpaste will be.I worry that the LED won't solder properly if I use 1:1 solder paste, that the LED will float away to one side or the other?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 29, 2017, 05:36:19 am
content: Why make the pads so oversized, but choke the soldermask down on them? It's not really pad then, because it's not solderable...I've seen very little reason to customize solder paste; I don't bother doing anything with very large pads either (which are usually drawn in chunks to get better uniformity). The assemblers customize the mask, and they know their process better than I do..To facilitate hand soldering on a part like this, I extend the pads (on at least one outer side) about 0.5mm beyond the package side (MMC).It won't float away, as long as the pairs of pads have made contact, which the paste should do. Once all four pads are touching with a solder fillet, no reasonable amount of solder will cause a problem; it will just float up higher.It could slide to one side and end up entirely on one pair of pads, if the heating is uneven or something. Making the pads narrow (so they are only extended in the lengthwise direction, say) prevents one dimension of it, at least.You can also refuse and make your boss purchase a hot air machine instead.Tim
LED grow light - Page 1
Forum section: electronics / projects

author: mazurov
author_rank: Frequent Contributor
timestamp: February 18, 2013, 02:00:37 am
content: Hello all,I recently finished building high-power LED light for my small grow room. The light outputs more than 25000 lumens, costs less than $300 in parts and pretty easy to build.Full write-up here ->https://www.circuitsathome.com/diy-2/high-power-led-grow-light-a-build-logEnjoy,/felis

author: BravoV
author_rank: Super Contributor
timestamp: February 18, 2013, 02:57:09 am
content: Cool & thanks for sharing ! Pity that poor cat !Mind share the details on the "fake" led ? Preferably a close-up shots.

author: mazurov
author_rank: Frequent Contributor
timestamp: February 18, 2013, 05:51:35 am
content: I don't have pictures, sorry. When I blow a mounted LED I buy ( an unmounted ) replacement from say Digikey and then look at both under a microscope. The difference is usually number of bond wires, genuine having more, like 4 instead of 3. Another sign is forward voltage, real ones have larger Vf, like 3.6V vs 3.2.
LED How many mcd for bright but safe in daylight? - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: May 09, 2020, 08:30:06 pm
content: Can anyone recommend suitable LED mcd specification that would provide a clearly bright but not dangerously bright illumination for outdoor use in a store front in daylight, to be visible from about 5' ?I will use an array of perhaps qty9, 1206 or 1210 LED's to form a square about 3" x 3"X X XX X XX X XColors: Red Blue Green
LED identification - Page 1
Forum section: electronics / projects

author: TheMG
author_rank: Frequent Contributor
timestamp: May 28, 2016, 03:22:44 am
content: I have a few salvaged LEDs from an unknown device. No markings on them at all.I'd like to see if anyone has any idea how much power I could safely run them at.I realize it will be impossible to tell exactly what they are, but if anyone recognizes the package type, die shape, etc and knows roughly what such LED packages would typically be rated for.I'm going to assume these should be rated for at least 3 watts, considering they were attached to small heatsinks in the device they came out of.
LED lamp bead display ESR test meter - Page 1
Forum section: electronics / projects

author: daisizhou
author_rank: Super Contributor
timestamp: May 03, 2019, 12:51:34 pm
content: Found an ESR meter.I am going to make itadvantage:1、Easy to use when repairing work(Don't want traditional analog or digital instruments,Obtaining ESR values also requires manual comparison,Capacitor performance is invalid)2、Just look at the LED to judge the work efficiencyI hope that interested friends will discuss

author: daisizhou
author_rank: Super Contributor
timestamp: May 04, 2019, 02:56:12 pm
content: Looks like( a real picture)

author: kripton2035
author_rank: Super Contributor
timestamp: May 04, 2019, 03:07:05 pm
content: this picture is NOT the schematic above.it is this one :http://kripton2035.free.fr/commercial%20esr/esr-zajic.html( and the schematic above is this one :http://kripton2035.free.fr/analog%20esr/esr-baliasov.html)

author: Tek Tech
author_rank: Contributor
timestamp: May 04, 2019, 03:29:36 pm
content: That's pretty neat.I have personal preference for a needle microamp meter in ESR meters.With the steady demand, simple construction, and very high prices of "factory-made" ESR meters, I am surprised that no one offers cheap ebay kits -- a PCB with parts could be less than $10. With case and meter: $20.

author: daisizhou
author_rank: Super Contributor
timestamp: May 05, 2019, 01:47:01 am
content: Yes,The physical map corresponding to the circuit diagram is not a picture like this.I hope that the appearance looks like a picture.I am still looking for suitable materials and workable tools.I am worried that the number of LEDs is too small.The measured ESR value is not accurate

author: daisizhou
author_rank: Super Contributor
timestamp: May 05, 2019, 01:52:10 am
content: Quote from: Tek Tech on May 04, 2019, 03:29:36 pmSimulating the esr table, I am worried that the measurement is not accurate enough.Of course, the analog table is easier to make.But after all, pure mechanical pointer deflection error,And the effect of gravity, leading to the deflection of the pointer
LED light pipe guide - Low cost source - Page 1
Forum section: electronics / projects

author: hcglitte
author_rank: Regular Contributor
timestamp: November 02, 2017, 06:22:14 pm
content: Hi,I am trying to source LED pipes for front panels. I can only find it on digikey etc, but not on aliexpress or similar Chinese places.Has anyone found these from low cost vendors?

author: thm_w
author_rank: Super Contributor
timestamp: November 02, 2017, 08:59:45 pm
content: Maybe you can post the specific kind, link to digikey?If you are buying reasonable quantity you will find them on alibaba.

author: hcglitte
author_rank: Regular Contributor
timestamp: November 02, 2017, 09:17:16 pm
content: This is an example:https://www.digikey.com/products/en?keywords=LFB025CTP%20I know you can find it on alibaba. But then you will have to buy a lot I guess, and for lower volume (1000 pcs) shipping cost will even it out.I would assume this would cost a couple of dollars for 100 pcs with free shipping on aliexpress (if a store stocked them), but on digikey we are talking 30 bucks(!) And that was one of the cheapest panel mount versions I could find...

author: cdev
author_rank: Super Contributor
timestamp: November 02, 2017, 09:31:09 pm
content: generic plastic fiber optics are fairly bendable and might save you some money.Or...https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=%22lite+brite%22&_sop=15

author: hcglitte
author_rank: Regular Contributor
timestamp: November 02, 2017, 09:35:14 pm
content: I would like the custom grooves etc so they stick on the panel. I am just a little amazed that these are not available on aliexpress.The project can handle the 0.2 USD price @ 500 pcs. But I am sure there must be some cheaper alternative out there...

author: hcglitte
author_rank: Regular Contributor
timestamp: November 03, 2017, 11:59:52 am
content: Actually, I will try skip using light guides. The design currently uses TH soldered LED's with LED spacers for controlling height.The LED's then fit into 3.5 mm holes in the panel which is 3 mm thick.The panel has an overlay where the LED hole indicators are transparent and diffused.Using narrow beam LED's (if needed) will most likely direct enough light into the 3 mm thick panel hole and then become spread in the diffused overlay.My design uses red, green and yellow LED's. In order to reduce unique BOM count I was thinking of using RGB LED's and switch yellow to blue.Less than one USD for 100 pcs:https://www.aliexpress.com/item/Wholesale-100pcs-RGB-POWER-TOP-1210-3528-SMD-SMT-PLCC-2-LED-Red-Green-Blue-New/32384196929.html

author: tszaboo
author_rank: Super Contributor
timestamp: November 03, 2017, 12:13:58 pm
content: Use digikey to find the right type, order it, test it. Contact the manufacturer to order a bag. It will be cheaper.
LED lighting batten drivers - Page 1
Forum section: electronics / projects

author: smartone
author_rank: Newbie
timestamp: August 16, 2024, 09:56:05 pm
content: Hi,In my workshop I have 12 LED lighting battens and the some of the drivers have failed.In side there is 2 aluminium PCB with a 72 LED on each PCB as ‘current’ Schematic.I am looking the get some constant current led driver to replace them.is it there any problem wiring as ‘option 1’ Schematic or is it best as ‘option 2’ Schematic.With option 2 I would have to modify the all PCBs, so a lot more work.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 17, 2024, 05:01:29 am
content: Option 1 will work just fine as long as the halves have the same current rating.

author: smartone
author_rank: Newbie
timestamp: August 17, 2024, 07:54:34 am
content: Hi,Yes all the LED are the same.They are L128-5090EA3500001 as i replaced all 1728 them 2 year ago.Look to replace driver with some 35w Osram Optotronic Intelligent Dali, they can be set to any current and are dimmable.

author: smartone
author_rank: Newbie
timestamp: August 18, 2024, 09:32:01 am
content: I have got it all wrong.See correct schematic.The question I should have asked is:What is the better circuit design Schematic 1 or Schematic 2

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 18, 2024, 12:19:53 pm
content: Have them in series, there's no guarantee the matching between the boards would ensure an even current split when wired in parallel.

author: Zero999
author_rank: Super Contributor
timestamp: August 18, 2024, 06:32:09 pm
content: You've posted many schematics. The one you refer to as Schematic 2 is not the correct one. Here's the right way to do it.
LED lighting for the lab: PWM driving - switching noise? - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: October 12, 2017, 10:59:50 am
content: Hi guys,I recenetly aquired a large amount (about 100 pieces, and I can get more if I want) of 1.2W 12V led modules (from the company baltled, they do lighting products for integration in outdoor signage). I wanted to use these to light up my lab/office. In other words, I will have large lines of them against the ceiling.My idea was to work with multiple separately controllable sections, so that I only light up what I need. As such, I was hoping to make my own driver circuits. Likely go from a large powerfully AC-DC supply to a number of separate outputs, each individually power-controllable.It seems to me it would be easiest if I could PWM them. Constant current driving is a pain since the modules are in parallel on the wire. I would also not want to do it in a switching supply since that is a lot more design effort than I'm willing to deal with (for now). So in order to dump a few tens of watts in heat somewhere would require large heatsinking, etc.I was wondering ifa) I should be worried about PWM radiating all kinds of noise. The loop length should be quite small since the modules are connected in a daisychain fashion. This is my electronics lab, so I think the requirements for radiated noise are a bit higher than usual.b) How do I protect the supply itself from excessive wear on the output capacitors if I attach a heavy PWM load? This will likely be constantly charging and discharging those output capacitors, and they could get quite warm.What kind of frequecies should I be looking at? I imagine higher will be easier to filter out and cause less issues with audible vibrations and such, but will also be harder to drive and radiat more easily? Any tips? Am I just getting worried about nothing?

author: xani
author_rank: Frequent Contributor
timestamp: October 12, 2017, 12:19:04 pm
content: You could meet it halfway and filter out PWM to something with manageable ripple before going to LEDs but honestly at that point you're halfway there in making a switching power supply
LED lightning balls - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 28, 2016, 02:29:54 pm
content: During my walk along the canal here last night, it occurred to me that it would be entertaining to toss something into the water that would emit brief, intense flashes to light up the water. I suppose at night you'd see the bottom against the dark sky.Anything like this exist or do I have to build it? Since it's in the water, hey, free heat-sink. Oh, and my RC boat would drag them back to shore.I don't want some weak-sauce illumination, I want nuclear-level white flashes. Like, it would light up people's faces.I don't know. I think that's what the Germans call a "schnappsidee", or in my case, a Caol Ila 12 idea.

author: TerraHertz
author_rank: Super Contributor
timestamp: May 29, 2016, 02:18:16 am
content: Xenon strobe sounds like the way to go. Does anyone still sell disposable film cameras? The film developers used to end up with bins full of those cameras, and they all had perfectly good flash circuits that ran off one or two aaa batteries. In my experience they were happy to give the used cameras away.Don't forget to include a prominent numeric LCD display, counting down to zero. For more hysterical headlines, and so the terrorism charges stick properly.How deep and clear is the water?Wouldn't it be more fun to have the flash go off at rare, randomly timed intervals, and never during daylight, plus have the balls sink to the bottom after a while (or be neutrally buoyant at say four feet deep), so they are really hard for anyone to find.