hybridfree/eevblog-posts huggingface dataset:
LED Light Switch - Page 1
Forum section: electronics / beginners

author: cvriv
author_rank: Frequent Contributor
timestamp: April 14, 2017, 05:15:46 am
content: This is a very basic problem that has me a bit confused. I got my hands on a few of these LED light switch things:https://www.amazon.com/COB-Wireless-Night-Light-Switch/dp/B016VCC7JMI was using them in my closet. I decided to gut them and rewire then to run off a 12 converter brick using one of the switches to turn them all on and off.When I opened up the switches I found two SMD strips (12 SMD's each), and a single 0.5w resistor. I measured the resistance of this resistor and measured 0.5ohms???Anyways, i wired three of them up in series and brought 8.5v across them and found they were drawing 150mA. They were very slightly warm to touch and just about as bright as they were when they were in their original state with freah batteries. Anyways.... I calculated that i need a 24ohm resistor to run the three in series across a 12v supply. The thing is that 0.5w will be dissipating during operation. I have a 24ohm 0.5w resistor but im not ok using it because that resistor gets hot as hell.Now my question is, and i should of ran them first with their guts hanging out, how were they running before I gutted them? They used four AAA batteries so thats 6v, 3v each, pulling at least 150mA. Thats almost a whole watt of power! You think these thing were cooking inside the whole time? Am i missing something here?Also does anyone know what type of LED strips those are? I tried google to find them but failed.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: April 14, 2017, 11:41:02 am
content: It's not unheard of for cheap LED lighting things to absolutly boil the living bits out of the resistors.Something that can easily be done if you don't have the right power resistor or don't feel great about the temperature it will be running, is just use 2 of half the resistance in series, or two of twice in parallel. This will double your power rating.If you only have 24ohm resistors, you can use 4: make two strings of 48 ohms and put those in parallel.Depending on how the LED's are wired up, you could also just look at getting a constant-current driver instead of a constant voltage one. They are quite cheap.

author: cvriv
author_rank: Frequent Contributor
timestamp: April 14, 2017, 12:48:34 pm
content: Thanks for the reply. Yea I already knew about the wiring of the resistors as such. I was just wondering if there was something I was missing when calculating power because like I said,... there was only one 0.5ohm 0.5w resistor inside each one. That's just craziness. Wouldnt last very long at all. Thanks.
LED lighting ideas for a project wanted - Page 1
Forum section: electronics / beginners

author: jonwil
author_rank: Contributor
timestamp: April 04, 2019, 11:03:32 am
content: Apologies if this is wrong forum, if it is can someone please point me to the right one?I am currently building a model of the Castlemaine Perkins Brewery out of LEGO bricks and I want to re-create the light up sequence XXXX sign on the roof as seen herehttp://cometravellingwithus.blogspot.com/2012/08/xxxx-brewery-tour-look-listen-learnthen.htmlCan anyone out there suggest what sort of LEDs or lighting system (and what sort of control board) I should consider using for the lights? And what might work for the X's themselves (LEGO makes lights but nothing that would work for this).Looking for something that can be powered from standard AA/AAA batteries (I can hide the batteries and control logic easily enough) and I intend the Xs to be about 2cm high or so to fit with the scale of the building. I hope someone can point me in the right direction.

author: soldar
author_rank: Super Contributor
timestamp: April 04, 2019, 12:38:56 pm
content: You could make the X directly with several SMD LEDs but it might be simpler for you to use just a couple regular, discrete LEDs behind a translucent plastic.

author: Nusa
author_rank: Super Contributor
timestamp: April 04, 2019, 12:59:57 pm
content: COB filament LED's are about the right size for the diagonals for DIY letters. You would need 2 of them for each X. You should be able to adjust the voltage to get the brightness you desire.https://www.aliexpress.com/item/5Pcs-Set-COB-LED-1W-Filament-Bulb-DC2-9-3-1V-130LM-Candle-Light-Source-Accessaries/32892399508.html

author: jonwil
author_rank: Contributor
timestamp: April 04, 2019, 08:12:48 pm
content: Anyone got any ideas for how to control this? As a programmer my gut says one of those cheap small microcontroller boards makes sense...
LED  lights interfering with the signal to cordless mic transmitter - Page 1
Forum section: electronics / beginners

author: Shane
author_rank: Newbie
timestamp: September 06, 2013, 08:51:23 pm
content: Greetings,We have just installed 36 LED19W bulbs in our church auditorium (160 more to come). And while it brightens the room a lot, I am experiencing high interference with the signal from LX2/58 TRANSMITTER it's VHF. Even when the mics are off the transmitter is showing there is a full signal when the LED lights are turned on. Any suggestions as to what would be the next best step in eliminating the static that is being produced would be greatly appreciated! Thanks!Shane SalmonLights and Sound Rookie

author: M. András
author_rank: Super Contributor
timestamp: September 06, 2013, 08:57:39 pm
content: crap cheap ledbulbsnothing else

author: AG6QR
author_rank: Frequent Contributor
timestamp: September 06, 2013, 10:52:06 pm
content: Replace the LED lights with incandescents.If you don't want to do that, replace the LED lights with units that are better designed and manufactured. I can't tell what country you're posting from, but in the US, the FCC has regulations about how much interference unintentional radiators are allowed to emit, and it is illegal to sell electronic devices that don't comply with FCC part 15.Depending on how bad the lights are, it might be that putting a ferrite choke over the power wires which are feeding them, with the choke as close to the light as possible, might cut the amount of RF interference being radiated by the power lines. That's about the only practical mitigating measure I can think of that wouldn't involve actually opening the lights up to see what's inside them.

author: tszaboo
author_rank: Super Contributor
timestamp: September 08, 2013, 11:00:40 am
content: Try wrapping the input wires of the LED lights around some ferrite cores. Put one light close to the receiver, and test it there. Can you put some link to the lamp, so we can maybe come up with some more useful advice?

author: kolbep
author_rank: Frequent Contributor
timestamp: September 08, 2013, 12:04:42 pm
content: Now might be a good time to switch to a Uhf mic. It will be on higher frequency range, and offer better immunity.some receivers can scan for interference, and change to avoid those channels.May also be a problem if the power supply for the receiver comes from the same d.b., or if any of the power or audio cables for the receiver run close to the lighting circuitd.
LED Lights PSU - Page 1
Forum section: electronics / beginners

author: scarr999
author_rank: Contributor
timestamp: August 06, 2025, 02:52:39 pm
content: I have bought 4 lengths of LED outdoor lights that all chain together from a single PSU (24v 1A) but they get dimmer the further away from the PSU (voltage drop) can someone post a link to a 240v AC to 24v DC PSU that will power these, I also would like a dimmer feature if possible and amazon would be great as I can return it easily if there are any issues. The voltage at the end of the LED's is 13.4v

author: themadhippy
author_rank: Super Contributor
timestamp: August 06, 2025, 03:42:10 pm
content: A psu aint gonna help much,instead feed power to both ends of the led strips and maybe also the mid point.

author: BeBuLamar
author_rank: Super Contributor
timestamp: August 06, 2025, 05:41:28 pm
content: If the chains are connected in series they should be the same brightness regardless of how far they are from the PSU. The current is the same.

author: Zero999
author_rank: Super Contributor
timestamp: August 06, 2025, 06:30:56 pm
content: Presumably these are LED strips.Use as thick as cable as possible.Move the power supply as close to the LED strips as possible.Don't connect them together. Feed each strip separately, preferably from both ends.

author: golden_labels
author_rank: Super Contributor
timestamp: August 06, 2025, 06:41:45 pm
content: BeBuLumar, the “if” part of your message is critical here. Yes, they would,ifthey were. They aren’t.LED strips are composed of short sections, each carrying a few to a dozen individual LEDs. You can see an example inthis photo from Wikimedia user BrentMauriello.Each such section is in parallel to each other, spanning across common power rails:Since the power rails show resistance, there is inevitably a voltage drop present. The entire situation becomes more akin to this picture:
LED matrix  - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: February 20, 2018, 08:15:03 am
content: I need to make LED matrix and sample drawing is attached (have drawn two path only ). Blue LED is working brightly. When blue led are ON, other color led are OFF. Green LEDs are working dimly. I couldn’t find the error path. Please guide me to find the error. PIC16f887 use switch D400 and ULN2803(it is not shown in figure)

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 20, 2018, 01:30:45 pm
content: Could be your choice of LEDs. To find out, test each LED by itself with the same amount of current bias in each and see how brightness varies. For the green LEDs you may be out of luxRegarding you general design, you need to ballast every parallel leg of LEDs (each leg should have its own resistor).

author: Zero999
author_rank: Super Contributor
timestamp: February 20, 2018, 01:52:43 pm
content: Green and especially yellow LEDs are often made from an older technology, such as gallium phosphide, which gives a very poor efficiency, compared to the newer indium gallium nitride, used in blue LEDs, which is much more efficient.For green, use indium gallium nitride LEDs, which is still slightly less efficient, power in/power out wise, than blue, but will appear brighter, because the human eye is more sensitive to green than blue.For yellow, use a phosphor converted InGaN LED, basically a deep blue/violet LED, with a fluorescent material and filter, to convert the short wave length light, to longer wavelength yellow light. Another option is to combine the light from high efficiency red and green LEDs, to make yelllow.Red LEDs are around as efficient as blue LEDs, but need a higher current, for the same brightness, because the forward voltage is lower: P = V*I. Red LEDs will appear brighter than blue, given the same power, at high light levels, but dimmer, than blue, in the dark, because the eye's sensitivity shifts from long, to shorter wavelengths, when it gets dark.

author: Raj
author_rank: Frequent Contributor
timestamp: February 21, 2018, 04:35:39 pm
content: use phosper coated leds,What they are is simple all blue leds which exites phosper coating to give out different color as final output
led matrix design consideratons - Page 1
Forum section: electronics / beginners

author: Jbates58
author_rank: Regular Contributor
timestamp: May 11, 2022, 10:22:05 am
content: hello all,I am looking to design a LED power product.Target state specifications are:primary supply voltage: 48-55VLED Power voltage: approx 30Vmax available power: approx. 10WI am looking for 900-1000 lumens per lightI am trying to understand the best way to approach the schematic design. and the balance between series and parallel layout. for example, say that the leds are 3v each, am i best off cramming 10 in series and calling it a day? or am i better breaking it into a 5S 2P configuration? or even 3S 10P?i understand the voltage current relationship, so to my thinking, the 10 in series would be the best option, but i feel that there are obvious caveats to this. I am also wondering if im best of incorporating an LED driver to handle it?I am new to the actual design thing, i have conceptualised ideas in the past before, however this is a product im looking to manufacture 30 or so of, and longevity is the key.Im essentially wanting to create a led panel light that will also be PWM driven.reasonable CRI would be good, but no need to spend mega to get a top notch CRI. but something decent (95+ i guess, im not sure tbh) is preferable.Thanks for the assist all.Jason

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 13, 2022, 07:54:37 pm
content: Putting lots of LED's in series is quite common. For mains powered LED's the total string voltage can go over 200V, and for TV's it's common to a low voltage power supply with a current mode SMPS that can have an output of 60V or even higher.Because this is so common in LED backlights for TV's and monitors, there are lots of chips especially designed for this.If you've already got a 50V power supply and only need 30V for your LED's then you need of course a step down or buck converter. (Using series resistors would be quite wasteful).But anyway, I would start by looking around what sort of LED driver IC's are available.
Led Matrix display drive mosfet question - Page 1
Forum section: electronics / beginners

author: Apothus
author_rank: Contributor
timestamp: April 02, 2017, 01:44:03 am
content: This is my first time building an LED Matrix display.It will display a simple animation driven by an atmega328p my question is regarding the mosfet architecture. I am a little concerned that I may have missed something with respect to driving the P-Channel fets in particular.The "Drive" signals are connected directly through microcontroller pin (currently missing 1K current limit resistor in series).LEDshttp://www.cree.com/led-components/media/documents/CLM4BRKWAKW1087.pdfP-Channelhttps://www.diodes.com/assets/Datasheets/DMP3099L.pdfN-Channelhttps://www.diodes.com/assets/Datasheets/DMG2302UK.pdfAny tips would be much appreciated.

author: Apothus
author_rank: Contributor
timestamp: April 04, 2017, 10:10:00 am
content: I have decided to pull the trigger and try out this design. Although I decided to drive the p-channel fets from an inverting demux to save some IO pins.

author: langwadt
author_rank: Super Contributor
timestamp: April 04, 2017, 10:57:12 am
content: pfet is the wrong way around, look at the body diode
Led matrix driver - Page 1
Forum section: electronics / beginners

author: dande
author_rank: Contributor
timestamp: November 24, 2014, 08:29:15 am
content: Hey there!I am creating a christmas gift with a 64 RGB LED matrix. I have most of the layout ready, also some parts of the code. It will be controlled by a ATmega328p and 4x 74hc595 shift registers. The first shift register will loop through every column (setting each HIGH and the others LOW), with the other 3 remaining for every columns' R, G and B. I'll probably use PWM or Bit Code Modulation to control the colors. The shift registers can source/sink a maximum of 70mA of current, and I believe I'll use more for each column.Should I put a N-MOSFET for every column, where the gate of the mosfet is connected to the 74hc595 and put a P-MOSFET on the rows (again gate driven by the other 2 shift registers) where the Source is connected to the rows and the Drain to the ground?I believe that I don't really need to put any resistors on the gate because of the high impedance of the MOSFET gate and the ringing is not really an issue for me. Am I correct?Thank you for your help!

author: dande
author_rank: Contributor
timestamp: November 24, 2014, 07:59:02 pm
content: Okay. After reading much more, I think I will go with PNP-s on both the source and the sink side, so 1 transistor will source the needed current for every row, and 1 transistor for sink the current for every column (x3 since, I am using common anode RGB leds).I think I will use a 2k resistor as a base resistor, but I am a bit unsure on that, could you point me to a direction, where I should check the maximum gate current?I will be using BC807s (http://www.nxp.com/documents/data_sheet/BC807_BC807W_BC327.pdf)Thank you!!

author: Zero999
author_rank: Super Contributor
timestamp: November 24, 2014, 11:00:03 pm
content: The base current needs to be high enough to reasonably saturate the transistor, at the desired collector current.The datasheet gives you the gain of the transistor at different collector currents and voltages.
LED matrix operation and max. lumens - Page 1
Forum section: electronics / beginners

author: Kjelt
author_rank: Super Contributor
timestamp: February 20, 2017, 11:45:48 am
content: Although I am not a beginner I realize that this topic is not my strongsuit.I have decent knowledge about matrix schematics multiplexing rows and columns with shiftregisters and transistors,I do have some questions about using standard white leds for this purpose, the led has the following specification:Inominal (nominal current) 50mA and 20 LumensImax (maximum current) only 1/10 DC (10%) 150mA and 50 LumensSo what if I want to drive this specific led in a matrix and want to have the maximum brightness of 20 Lumens per led ?At Imax I need to operate it for 40% DC in order to get to the 20 Lumens.Does this mean I can only operate it at the 10% DC which will give me max 5 Lumens ?So the questions:- does this mean this Led can not be operated with higher brightness than 5 Lumens in a matrix?- are there special leds for matrix operation that can withstand lets say 1Amps at 10% DC ?- are there other practical solutions available (for instance not multiplexing but driving each and every single led)

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 20, 2017, 11:51:50 am
content: You can't generally get the max possible brightness on a multiplexed display. You also have to take thermal considerations into account.Where brightness is really importand I'd normally not use more than a 4:1 multiplex.Bear in mind that perceived brightness ( and usuelaly LED output vs. current) is not linear, so, for example, a quarter of the current is typically only going to be approximately half as bright.White LEDs in particular are very efficient, so unless you want particularly insane brightness it's rarely an issue. Do some tests to see what current you really need.

author: Kjelt
author_rank: Super Contributor
timestamp: February 20, 2017, 11:58:26 am
content: Thanks Mike,do you recommend using a higher refresh/scan frequency with lower amperage or a lower frequency with higher amperage ?

author: cowana
author_rank: Frequent Contributor
timestamp: February 20, 2017, 12:54:51 pm
content: Frequency is less important than % duty - if you can increase the percentage time the LEDs are on for, that'll do more for making them look brighter than increasing the current by the same amount.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 20, 2017, 02:01:02 pm
content: Frequency doesn't generally matter brightness-wise, it needs to be high enough to avoid flicker - I usually aim for 250Hz for a full scan if possible, but you may be able to do with half that in some cases.For an X/Y matrix, interlacing the row scan order can help reduce flicker.
LED module forward voltage - Page 1
Forum section: electronics / beginners

author: duncan16v
author_rank: Newbie
timestamp: April 14, 2025, 05:21:22 am
content: Hi allThis one's a newbie question and I'm a little embarrassed that I don't know the answer myself. However...I am repairing some LED light fittings where the LED module has failed (they're 14 years old so arguably fair do's). The LED driver is a Philips unit whose output is 50V DC @ 700mA, and the original LED module is LUXEON LXM3-PW6-L6C 9-LED module which I haven't been able to find a datasheet or direct replacement for. The LED chip that looks like being the best option is a single LED module rated at 34V and 900mA.Can I use the Philips driver even though it's output voltage is significantly higher than the rated forward voltage of the chip? I understand that the 700mA of the existing driver means the LED won't get to full brightness, but that shouldn't be an issue looking at the spec sheet.ThanksDuncan

author: Zipdox
author_rank: Regular Contributor
timestamp: April 14, 2025, 02:17:26 pm
content: LED drivers are constant current sources, so it should be possible. I can however not guarantee that the driver will operate at such a low voltage, as I don't know anything about it.

author: edavid
author_rank: Super Contributor
timestamp: April 14, 2025, 02:39:24 pm
content: Quote from: duncan16v on April 14, 2025, 05:21:22 amThe numbers don't add up. A 9 LED series wired module would have a forward voltage of 30-32V. Why do you think the driver produces 50V?(And obviously your replacement is not a single LED.)

author: tunk
author_rank: Super Contributor
timestamp: April 14, 2025, 03:33:21 pm
content: It may help if you post the Philips model number.Also, google does not find LXM3-PW6-L6C.
LED Pot lights, UL/ETL listed vs cheap non UL - Page 1
Forum section: electronics / beginners

author: Paranoid
author_rank: Newbie
timestamp: June 29, 2022, 12:04:36 am
content: Hello,So I purchased 4 LED pot lightsThe first two are super cheap 3$ a piece including one with fake UL listingThe two other are 8$ a piece and 14$ a piece.Are the two cheap ones actually missing any safety components ? And are they fire risk ?Thank you
LED Replacement for 18" T8 Bipin flourescent tube without ballast - Page 1
Forum section: electronics / beginners

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 29, 2023, 10:36:44 pm
content: I have a desk lamp which has 2 18" T8 Bipin flourescent tube. It has the kind of manual ballast that you have to hold the start button down for a second or so to heat the bulbs. I want to convert it to LED but and wonder which is the best option. I would like the color temp of 5000K if possible.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: May 29, 2023, 11:31:28 pm
content: Basically you have to decide which way you want to attack it. Retrofit or plug and play.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: May 29, 2023, 11:42:24 pm
content: Getting a pair of 18" LED T8's might be tricky. Do you have a source in mind or were you wanting to maybe 'trim' a more commonly available length?

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 30, 2023, 12:05:01 am
content: I don't have a source that's why I asked. And yes I alreday decided ( the lamp decided for me) that I would need the type B because the type A requires electronic ballast which the lamp doesn't have. It has a manual ballast you have to start it manually by holding down the red button. So I have to use the type B which doesn't require a ballast. However, I don't seem to be able to find the type B for the 18" tubes.

author: Kim Christensen
author_rank: Super Contributor
timestamp: May 30, 2023, 12:13:12 am
content: The other term to search for instead of type-B is "direct wire"...Found these:https://www.lightup.com/led-t8-tube-7w-directdrive-keystone.html
LED Replacement for Jansjö Ikea light - Page 1
Forum section: electronics / beginners

author: jester206
author_rank: Newbie
timestamp: May 16, 2018, 05:51:17 pm
content: Hello all!I bought a Jansjö work light from Ikea. I like the light and I wanted to use it on a small aquarium I have but the color temperature doesn't match another light on the same aquarium. I think it is 3000k and I would like it to be around 6500k. I wanted to see if it was possible for swap out the led for a different one. I haven't yet pulled it apart yet because after reading about other people taking them apart is sounds a little finicky plus if i cant replace it I don't want to risk breaking it. I did however findanother poston here of someone that has taken it apart. There seems to be different versions of the chip inside this lamp but I'm pretty sure this is the same one i have. I think it's a SMD 5050 LED? Correct me if I'm wrong.So my question is:Can I just find a replacement for this board with a 6500k LED and just do a straight swap out? I tried looking online but I could only find leds on starboards. None of them had the extra components soldered to them thou, just the led. OR would i have to de-solder the led and replace it with a different one? If so, do you have any tips for doing that? I've never soldered anything that small the the surface of a board.

author: tooki
author_rank: Super Contributor
timestamp: May 17, 2018, 11:31:56 am
content: Just FYI, since the PCB is aluminum heatsink board, desoldering will be a bitch. You’ll probably need to preheat the board, and then use two irons to remove the LED.
LED ring on USB 5V - Page 1
Forum section: electronics / beginners

author: edy
author_rank: Super Contributor
timestamp: September 23, 2012, 08:21:57 pm
content: Hey Folks,I just want to confirm something. I bought an LED ring lamp that hooks up to a laptop USB, took it apart and here's a photo of the switch and part of the ring. The LED's are all hooked up in parallel obviously.So I see they used 3 SMD resistors all labeled "330" which is 33 ohm, also placed in parallel. Total resistance of this combination is: 1/33 + 1/33 + 1/33 = 3/33 = 1/11. ..... 11 ohm.Some dumb questions:1. Why use 3 resistors instead of 1?- does it improve "accuracy" or tolerance, or worsen it?- is this a safety issue?2. What is the characteristic voltage-amp curve on these unknown white LEDs?- If I want to drive them using 3 AAA batteries (4.5 V?)- If I want to drive them using 2 AAA batteries (3.0 V?) - if even possible- What resistor would you recommend, or do I even have to change anything?On another note, I have a whole bunch of LED's bought in China by a friend who brought them back. No spec sheets or anything. How do I go about figuring out the right resistors based on various input voltages (battery multiples like 3, 4.5, 6V) and also 3.3V and 5V (for use with a micro-controller).How would you recommend I start testing them so I don't burn them out?For example, if I hook up an amp-meter or volt-meter, what do I look for?Thanks!

author: SeanB
author_rank: Super Contributor
timestamp: September 23, 2012, 08:39:31 pm
content: Being 5mm units i would not drive them at over 20mA, and even then they might fail due to poor manufacture.As to the LED ring, the 3 resistors are used for power dissipation, it will work fine as is off 3 AAA cells, but may only run a short time on 2 or may only light dinly.
LED Spotlight bulbs. - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: January 30, 2018, 10:29:01 pm
content: I replaced all my GU10 240V spotlight bulbs... all 18 of them with LED variants. In the man cave and kitchen I put 5W cold daylight and in the bathrooms and living room, 3W warm white.They are great. The 5W are brighter overall than the 20W halogen's that I had. The 3Ws light the bathrooms perfectly.The downside is they are diffused with a clouded screen which kinda negates the "spot light" effect and spreads the light out. I have two pointing down at my work bench and the effect is not as good as the halogen spots.Question: If I persuade the diffuser cover off the bulbs it's unlike to damage them right? It should restore the harsh spotlight effect for a workbench light? The risk would then just be blinding myself, as looking directly at them for even half a second with the diffuse cover on leaves me with a ring of square LED retina burns!

author: Zero999
author_rank: Super Contributor
timestamp: January 31, 2018, 09:35:04 am
content: Removing the diffuser could pose a shock hazard, if it exposes live parts.Not all LED spot lights have diffusers. Why not replace the ones over your workbench with the type which don't?

author: Kjelt
author_rank: Super Contributor
timestamp: January 31, 2018, 09:45:57 am
content: I am facing a similar issue.I have the ambience white GU10 hue spots that shine their light in at around 160 degrees.Just removing the "diffuser" will not help you since the light from individual leds will give a lightpattern, not nice.What I need since I can not remove the current 160 lens is some lens to,put in front to focus the light to the 25 and 15 degrees angle I want. Sounds silly but I am going to my glasses shop for help, probably costing twenty euro per lens or soWhat you can do is replace the current lens with the one you want but therefore you need to know how the spotlight is constructed. Are there three 1W powerleds in the Mercedes star construction then you can find a lot of options on Ebay, many lenses are sold seperately. If there are ten or so medium powerleds it will become very hard to focus that light since it is intended to be a diffuse light source.

author: james_s
author_rank: Super Contributor
timestamp: February 02, 2018, 06:01:07 am
content: There are (or were) some cheap lenses available from China for LED lighting. I think I got the ones I have from DealExtreme back when it still made sense to build my own LED lights.
LED Strings and current sharing - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: August 09, 2022, 04:53:08 pm
content: HelloI wanted a PCB with 20 CLQ6B-TKW RGBW Leds with 48VDC power supply.I do not want a voltage boost led driver. It has to be a set-down Buck converter (4 actually). One for each color + white, but as you know 48VDC is not enough.So the solution would be to parallelize the LEDs, 2 parallel string of 10LEDs @0.2mA for each led driver.Since every LED has a different forward voltage, will it be a problem???I mean 10 LEDs in series, statistically, I would say the 2 string will have approximately the same voltage drop, no?Or will I need to measure the forward voltage of each LED, an select the right ones to create a balanced strings?

author: mariush
author_rank: Super Contributor
timestamp: August 09, 2022, 05:34:11 pm
content: Only 20mA on each led?those leds are rated for almost 200mA on each color, and the forward voltages are specified at 100mASee bottom of page 2 in datasheet :https://cree-led.com/media/documents/CLQ6B-TKW.pdfred : avg 2.1v max 2.6vgreen: avg 3.0v max 3.8vblue : avg 3.1v max 3.8vwhite: avg 2.9v max 3.6vFor red, you could probably have all 20 in series, I doubt the total forward voltage would get close to 2.3v x 20 = 46v so even a linear driver should work fine (need around 1-2v drop inside the linear driver)for the others, I'd do calculations with a forward voltage of 3.2v in mind .... if you bin them then the two series of 10 should have close enough voltages to work in parallel.You should decide on the max current you're gonna have and then buy maybe 100 leds and bin them at that current you chose, so they're fairly close to each other.

author: tooki
author_rank: Super Contributor
timestamp: August 09, 2022, 05:39:39 pm
content: Quote from: Tantalum on August 09, 2022, 04:53:08 pmPlease explain what you’re trying to accomplish.Fundamentally, you use current limiting resistors on each string of LEDs, with the resistor selected to drop the “excess” voltage at the desired current.Look at ledcalculator.net, it illustrates it nicely.Quote from: mariush on August 09, 2022, 05:34:11 pmWhere do you see 20mA? The OP wrote “0.2mA”, but I assume they mean 0.2A per string, as you identified in the datasheet.

author: clairemattockskth67
author_rank: Newbie
timestamp: August 11, 2022, 05:03:18 pm
content: waiting for an explanation
LED strip light - Page 1
Forum section: electronics / beginners

author: rupesh
author_rank: Newbie
timestamp: April 22, 2015, 01:25:26 pm
content: i am new in designing so please go through this and help me .I want to make LED strip light using SMD 2835.The data sheet is provided below.The forward VI characteristics shows 75mA at 3.3 V.The relative luminesence intenisty at 75mA is 110%12 V,1 Amps DC is used as the source .I have 3 LED's in a single strip, and a resistor to limit the current flow to 75mA.(but as per the available resistance 63.6mA flows through it)http://ledcalc.com/#calc-LEDresistor calculationThe resistor value is 28 Ohm and the nearest high rated resistor is 33 Ohms.input power=12Wpower abosrbed in single strip =(12*63.6=0.7632W)The maximum parallel strip i can connect to 12V,1A DC supply =(12/.7632) =15 strips which means 48 LED and 15 resistors in total.ORfrom the economical point of view can i limit to 12 strips by allowing 80 mA current to flow through it by a 39 Ohm resistorSo anyone please go through these and guide me,

author: PSR B1257
author_rank: Frequent Contributor
timestamp: April 22, 2015, 01:50:39 pm
content: QuoteIf a 33 Ohm resistor gives you 64mA, how can a 39 Ohm resistor result in any more currentYou should drive the LEDs at 100% (or less) nominal current. No need to go any higher than this because your eye (and everyone else human eye of course) can't really thell the difference anyway.Test it for yourself. 1/4 of the nominal/initial LED current looks just like 1/2 of the nominal/initial brightness.

author: mariush
author_rank: Super Contributor
timestamp: April 22, 2015, 01:59:52 pm
content: The absolute maximum rating for those leds is 90 mA. All the measurements in the datasheet are done at 60mA, so you should probably run those leds at around 60-70mA, don't push them higher.Also, note that you'd need some space around the leds to act as heatsink or design double sided pcb with lots of vias from the top side to the other side to transfer heat from the led side to the copper on the back.Using resistors to limit the current is the most basic way of driving leds, there is some power wasted in the resistors ( p = i^2 x r = 0.063x0.063x33 ohm = 0.13w so you'd need at least 0.25-0.5w resistors)... with 15 strips, you'd waste 15x0.13w = 2 watts on the resistors alone... with a 12v 1A power supply that means you have about 80% efficiency.From the way you wrote your message, it feels like you're a beginner so resistors is probably easiest for you.If you're willing to experiment, I'd suggest removing the resistors and using led drivers to have finer control over the current going into the leds, and better efficiency.There are boost led drivers that would allow you (for example) to put up to about 12 leds in series (as long as the total voltage doesn't go above around 36-38v) and drive them from low voltage like 12v at current you want without using resistors, achieving 85-90% efficiency this way. You'd need an additional inductor and maybe a couple of diodes and capacitors but in some cases it's worth it.
LED strip lighting even without a positive terminal - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: July 17, 2018, 02:56:09 pm
content: hello everyone..I have been making a project with some 12V RGB LED strips. while trying to check the LED strips I found something interesting. I just connected the ground terminal from a 12V wall adapter to the terminal "B" and left the positive terminal disconnected to the strips but, while touching the positive terminal on the strips with my finger I saw that the led strips are lighting up with a very low brightness. This also happens even when i tough anywhere in the strip with my finger. I wonder how this is happening. anyone could explain to me about it. I'm attaching a pic of the test that I have done.
LED strip - Page 1
Forum section: electronics / beginners

author: Markusjames
author_rank: Newbie
timestamp: April 08, 2018, 02:40:56 pm
content: In this schematic can I use the flow from Diagram B? I understand that Diagram A is the correct +12V Input supply and I can measure the end of the led with the same voltage and can also continue to link another led strip. With Diagram B to supply +12v supply it will still turn ON the LED but the end of the LED is 0v. I hope I'm making any sense. I already installed the LED strip underwater with Diagram B. I want to know will my mistake break my PSU and can cause issue on both LED and PSU? although its working. Thank you so much for your help.

author: mdijkens
author_rank: Regular Contributor
timestamp: April 08, 2018, 03:38:26 pm
content: As far as I can see, B is wrong!You can put your 12V on either side, there's no differenceAt the other end you'll still have 12V

author: tpowell1830
author_rank: Frequent Contributor
timestamp: April 08, 2018, 03:42:24 pm
content: Hi Markusjames, welcome to the forum. You will find many answers here, some will not even be related to your question, however, be patient because someone will answer.As for your diagram, the circuits are identical, with the exception of the horizontal arrows, which i do not understand, therefore I don't understand your question. Perhaps someone else will understand, or you might try to rephrase your question. I know it is difficult when you are a beginner.

author: Brumby
author_rank: Unknown
timestamp: April 08, 2018, 03:50:44 pm
content: The only error in your diagrams is the label: "0v output" Either remove it or change it to "12v output".If we use the typical convention of using the earth/ground/chassis connection as the zero volt reference, then that 0V exists all along the bottom rail in each diagram. Likewise, the top rail is at 12V ... along the entire length.As said above, both diagrams are electrically identical. The only difference is the end which is connected to the supply.The only 12V to 0V arrow you can really draw is one along each LED string.Excuse my stupidity. Just read your post again.Something unusual is going on - and I'd be asking a couple of questions....

author: sokoloff
author_rank: Super Contributor
timestamp: April 08, 2018, 04:01:41 pm
content: It’s possible that there is a diode or regulator hidden in the strip that you can’t see and haven’t put on the circuit drawing.If the circuit is as drawn, connecting the supply anywhere on the top wire is electrically the “same”, so I suspect a difference between the strip on your bench and the diagram.

author: Brumby
author_rank: Unknown
timestamp: April 08, 2018, 04:12:00 pm
content: This is one of themQuote from: sokoloff on April 08, 2018, 04:01:41 pmAnother is to double check the measurement connection at the left of diagram B.

author: paulca
author_rank: Super Contributor
timestamp: April 09, 2018, 06:46:54 am
content: Do you have a specific LED strip in mind or are you making one?If you have a particular LED strip in mind a link to the product will help.
LED stripe controller IC identification - Page 1
Forum section: electronics / beginners

author: juanmadg
author_rank: Newbie
timestamp: March 06, 2022, 07:43:11 pm
content: Hello,I'm new to the blog! I'm trying to identify a SOP8 or SOIC8 controller IC, marking D93-6 2116 (see attached picture).This is an IC I have found in a 50 LED lighting stripe; I liked the solution because it is simple and elegant; they have divided the 50 LED stripe in two halves (alternating LEDs in each half) and inversing their polarity so driving the output positive lights the LEDs in one of the halves and driving the output negative lights the LEDs on the other half. The PCB is marked as FG-3AA-ZF-V4 (see attached picture).The circuit is very simple, single sided PCB, the controller IC with a 32768Hz quartz crystal directly connected to the IC without capacitors, one push button for changing lighting modes connected to one IO pin and the led stripe in just one cable (2 wires) connected to two output pins of the IC in series with a 20Ohm SMD resistor (marking 200).The LEDs are driven via PWM at 100Hz or 3Khz depending on the lighting mode. The current through the LEDs must be small as it is always passing through this 20Ohm SMD resistor in series with the LEDs. As the voltage on the output has a peak value of around 2,68V, given an approximate 2V voltage drop for the LEDs (different colours), it will be around (2,68-2V)/20 = 34mA, which could be in the manageable range of standard digital IO pins. Identifying the IC would allow us to know whether this PWM is simulated in software or has a hardware support. This could also be some type of cheap H-bridge toy motor controller with an integrated MCU and the manufacturer might be taking profit of the H-bridge to drive the LEDs with direct and reversed voltages; in this case, most probably the PWM functionality would also be embedded in hardware.The IC pinout seems to be like this:1 - GND2 - LED output 13 - GND (an unused IO pin?)4 - Push button input IO5 - VCC6 - LED Output 27 - OSC 18 - OSC 2I have also attached a couple of pictures of the signals driving the LEDs I took of the oscilloscope.Googling for the IC markings either as MCU or H-Bridge motor controller with MCU didn't give me any meaninful results. Any suggestions will be appreciated.Best regards.

author: devinatkin
author_rank: Contributor
timestamp: March 22, 2022, 02:49:38 pm
content: I checked LCSC to see if I could find it for you, but no luck. Why are you interested in finding the chip? (It's likely some chinese one which I just was unable to find). There may be some decent replacements out there.
LED & TOF - PCB Design Help - Page 1
Forum section: electronics / beginners

author: reallydoesntmatter
author_rank: Newbie
timestamp: September 16, 2020, 04:08:16 pm
content: Hello everyone,I'm currently working on a long term student project in which I'm designing a lamp and would be very greatful for a little help with the PCB design. Im quite a novice to electronics in general, my experience is limited to some Arduino tinkering etc., so be patient with me!The lamp itself is a long array of LEDs, that should be avaliable in different lengths. So I decided on a modular design. A central "intelligent module" receives 12V, contains a micro (ATtiny85 is my idea so far) for dimming the LEDs based on a signal by a VL53L0X TOF Sensor for simple gesture control. It also contains 6 LEDs. Then, 4, 6, 8 or 10 "dumb modules" attach to that central module, which contain 7 LEDs.For the LEDs i was planning to use theOSRAM OSLON SSL 80 GW CS8PM1.CMor comparable. They use around 1W at 2.85 V.One major limitation is the space I have on the PCBs. They should be around 140 x 10 mm, maybe I can stretch it to 12mm or in the worst case 14mm.So i have a couple of questions, and I'm sure more will come with time:Q1: What would be the best way to dim the LEDs? An LED-driver on each module with a 12V supply and a PWN signal by the ATtiny? What kind of driver would be suitable?Q2: Is it realistic to put all this current through these PCBs? Should I be using aluminium core PCBs?Q3: Is the ATtiny a reasonable choice for this, with potential gamma correction for the LEDs and smooth dimming?My idea of the schematic so far, still missing everything related to the LEDs:Any criticism or new ideas are very welcomed!Thank you in advance!Jasper
LED Track light powered from two sources. - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: February 14, 2024, 05:07:08 pm
content: Here two circuits from Lighting DB 2(LDB2) R4 and R5 are given in one track(track lighting). My question is can power be supplied from two separate mcbs from one DB to the same point (i.e to the same load).

author: jwet
author_rank: Frequent Contributor
timestamp: February 16, 2024, 02:30:29 pm
content: I'm not an expert but seeing no replies, I'll give you my opinion. Perhaps wiser men can chime in and correct me.If I understand it correctly, it doesn't sound right.I guess the designer wants to able to have all lights on one MCB and a few others on a secondary MCB for house lights and dimmed lights. It marginally OK if the two MCB are interlocked so they can be on at the same time but if they are both powered it creates some real problems- here are a few.1. Worst case, if using 110v circuits, the two could be from opposite legs across neutral and paralleling them directly short the 220V combination.2. Even small drops in voltage caused by different loading on the two legs could cause large currents to flow in unintended directions3. It creates a hazard for a future electrician that disables the circuit at a breaker only to find its fed by the other.If you have separate control of the coil and load circuit of the MCB, (like a relay) and you used only one source, it would get rid of all 3 of my objections.

author: Towger
author_rank: Super Contributor
timestamp: February 16, 2024, 03:34:34 pm
content: Certainly not in my country and I assume the same in others.There is a safety/confusion issue when isolating the circuits on the MCB(s). What ever about different phases etc.

author: Gregg
author_rank: Super Contributor
timestamp: February 17, 2024, 02:13:30 am
content: Look at the legend; upper right in the larger drawing. It shows the track to be 3 circuit track. In another page or a detail it probably shows which circuit feeds which track. All of the lighting may originate from a lighting control panel.
LED viewing angle spec (ie 100 deg x 40 deg) - Page 1
Forum section: electronics / beginners

author: TimNJ
author_rank: Super Contributor
timestamp: July 05, 2014, 05:05:45 pm
content: I was going to stock up on some LEDs off of Mouser. I noticed that some of the LEDs, mainly Cree, had a viewing angle spec of something like 100 deg x 40 deg, or 70 deg x 35 deg.What does this mean?For reference,http://www.mouser.com/ProductDetail/Cree-Inc/C5SME-RJS-CS0U0BB2/?qs=sGAEpiMZZMvHYEB9WUp7EhB9pKgyKqOlZUuWyx%252b3ltw%3d

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: July 05, 2014, 05:42:12 pm
content: A classic round LED would produce an illuminatedcirclewhen shining perpendicular to a surface.The LED you mentioned, would produce anovalshaped illumination pattern in the same circumstance.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: July 05, 2014, 05:45:10 pm
content: Also note:Quote

author: TimNJ
author_rank: Super Contributor
timestamp: July 05, 2014, 06:00:05 pm
content: Oh wow, so looking at it from one side you can get 100 degrees, and if you look at it from another you get 40 degrees of visible light.Thanks. I didn't even notice I was looking at ovular LEDs. What's the application of ovular LEDs?

author: David_AVD
author_rank: Super Contributor
timestamp: July 05, 2014, 09:13:48 pm
content: Oval LEDs are used when the desired viewing angle is much wider in one plane. Think of an LED scoreboard or sign. The viewers may be all at a similar height but spread out horizontally. If you use regular round LEDs there's a lot of wasted light in the vertical plane that could have gone to the horizontal one.

author: TimNJ
author_rank: Super Contributor
timestamp: July 05, 2014, 09:53:59 pm
content: How intelligent!