hybridfree/eevblog-posts huggingface dataset:
LED lights and effciency - Page 1
Forum section: electronics / projects

author: audi80
author_rank: Newbie
timestamp: January 12, 2014, 07:16:46 pm
content: Hi peopleWhen i buy a good quality LED bulb E27 (Philips or Osram) it has around 100lm/w efficacy. Since the theoretical max is around 650lm/w, that gives a effciency around 15%.What does the energy goes to, that doesn't goes to light? Heat, radiation, uv light, ultraviolet light, or?Was just wondering...Kind Regards

author: SeanB
author_rank: Super Contributor
timestamp: January 12, 2014, 07:36:49 pm
content: The rest is almost always going as heat in the driver and the die.

author: muvideo
author_rank: Frequent Contributor
timestamp: January 12, 2014, 08:03:29 pm
content: Hello,that figure is for pure green, where our eye is most sentitive.White light contains spectra of light where the eye is far lesssensitive, so the theoretical maximum efficacy for lighting dependson the spectrum of emitted radiation.It's a complex thing, I'm going by memory but to give you somenumbers: for usual led lights (phosphor converted blue leds)the theoretical maximum is somewhere around 300-350lm/W,for more info search LER "luminous efficacy of radiation" on google.A 100lm/W light is converting about 25%-30% or less of inputpower in radiation overall. The balance is converted in heat bypower supply, blue led, and phosphors. The blue led shouldbe the weakest link, at less than 50% efficiency.Ciao!

author: audi80
author_rank: Newbie
timestamp: January 12, 2014, 08:21:49 pm
content: Hmm, I'm comparing lightbulbs for home use at the moment.I have no scientific proof but my personal experiance is: a flurecent light bulb with the same efficacy, gets a lot hotter.If i could use the heat form the lightbulb (which i can in Scandinavia) why would i choose LED lighting?

author: Ghydda
author_rank: Regular Contributor
timestamp: January 12, 2014, 08:37:35 pm
content: @muvideo --> superb explination.@audi80 --> the hotness of an object is not only a result of the power dissipated.The temperature rise is a product of power dissipation times the thermal resistance to the ambient.LEDs need to be cooled quite hard (a low thermal resistance) to achieve any serious lifetime, therefore for a given power level they run fairly cool(ish), whereas the arc inside a CFL needs only to be cooled adequately (a higher thermal resistance) to not melt the glass tube (simplified explanation).You should not by LED lighting if you don't want to.But the best LED bulbs trumps the best CFLs in converting electrical energy into usable light.Also the worst LED bulb are so bad, that a bog standard CFL runs circles around the worst LED bulbs - both in light output and in the persived quality of the emitted light.
LED logic sequence circuit question - Page 1
Forum section: electronics / projects

author: mp
author_rank: Newbie
timestamp: June 07, 2019, 05:25:14 pm
content: I would like to build an electronic circuit that would consist of a magnetic contact switch on a window, wired to a compact sized, low battery drain electronic circuit to control an LED and a relay switch (or similar) to connect a high voltage light, following this logic sequence:Window closed LED off & relay switch open circuit -> Window opened LED immediately turns on & relay switches to closed circuit -> Window closed LED remains on & relay returns to open circuit -> Window opened LED remains on & relay switches to closed circuit -> Window closed LED turns off & relay returns to open circuit -> Cycle repeats...Hopefully low current draining components are available and components that allow the logic sequence to be easily reconfigured in a different way. Also, a push button sequence reset function would be good.

author: mariush
author_rank: Super Contributor
timestamp: June 07, 2019, 11:09:27 pm
content: Any Arduino or PIC microcontroller can do what you want, and can run on a 4 rechargeable AA batteries (4x1.3v max = 5.2v) for months. Technically, they could run on a 3v CR2032 battery but the relay needs a lot of current to switch states so a single coin cell battery would not do.Configured at 1-4 Mhz, such a microcontroller will use mA worth of current, very little.You can use ADC or i2c or whatever to monitor the change in magnetic field at the window (when window opens, magnet on window moves away from sensor so the reading changes and the microcontroller reads that change and does the job)You can use a 5v bi-stable relay to do the job, and you can power it directly from batteries. You switch states by sending 5v through a relay pin for a few secondsHere's an example of 5v dual latching relay :https://www.digikey.com/product-detail/en/omron-electronics-inc-emc-div/G5RL-K1-E-DC5/Z4395-ND/4947136Send 5v for more than 30ms and it switches on and then uses no power to remain on.Send 5v for more than 30ms on another pin and it resets.
LED luminosity at double the current - Page 1
Forum section: electronics / projects

author: rea5245
author_rank: Frequent Contributor
timestamp: July 15, 2016, 11:48:02 pm
content: Hi,I have a 16 segment LED display. I put 20mA through one of the segments and 10mA (actually 8mA) through another. The datasheet shows a linear relationship between current and luminous intensity: double the current is double the intensity.But to my eye (and my wife's eye) the two segments seem to be equally bright. Is that just the way human perception is? If so, how useful is luminous intensity as a metric?Thank you,Bob

author: Dave
author_rank: Super Contributor
timestamp: July 16, 2016, 12:04:24 am
content: The human eye is far from linear, doubling the intensity will hardly make a noticeable difference.You'd need to reduce the luminous intensity to about 1/6 to perceive it as roughly half the brightness (this of course varies from person to person).

author: danadak
author_rank: Super Contributor
timestamp: July 16, 2016, 01:48:52 am
content: Google this "human eye luminosity characteristics", lots of hits.Regards, Dana.

author: StillTrying
author_rank: Super Contributor
timestamp: July 16, 2016, 02:00:11 am
content: Quote from: rea5245 on July 15, 2016, 11:48:02 pmIf you've got a half-proper digital camera you can roughly check.Close-up photo the LED at 1/500th, then double the current and close-up photo it at 1/1000th, then see if the LED is equally exposed in both photos.

author: georges80
author_rank: Frequent Contributor
timestamp: July 16, 2016, 04:35:09 am
content: Yeah, human eye is close to a log response (for light intensity) and that's not even figuring in the iris.Much like your ears. 2W isn't twice as loud as 1W... 2000 lumens isn't twice as bright as 1000 lumens.It's also why dimming LEDs is great, you can half the current (power) with minimal impact on perceived brightness.cheers,george.

author: Fungus
author_rank: Super Contributor
timestamp: July 16, 2016, 06:05:16 pm
content: Quote from: rea5245 on July 15, 2016, 11:48:02 pmYes.
Led matrix (homemade) - Page 1
Forum section: electronics / projects

author: Electronicshacker132
author_rank: Newbie
timestamp: June 30, 2017, 07:30:18 am
content: This is something that I made by my self as I felt bored.There is a picture of the display.It has a resulution of 4x5 and it is more monochrome green.It isn't perfect and it is dim even in pitch black but it does the job.

author: fourtytwo42
author_rank: Super Contributor
timestamp: June 30, 2017, 07:53:22 am
content: Welcome and very neat, but could you show it displaying something so we can see the contrast ?

author: mikerj
author_rank: Super Contributor
timestamp: June 30, 2017, 12:24:49 pm
content: Quote from: fourtytwo42 on June 30, 2017, 07:53:22 amPerhaps it's very, very dim...
LED matrix controlled remotely - Page 1
Forum section: electronics / projects

author: WILDERNESSBAGEL
author_rank: Contributor
timestamp: March 18, 2022, 01:30:50 pm
content: Hi, I have a standard LED matrixhttps://www.ilikitled.com/, I'm wondering if there is a simple way of controlling the LED content "online" for example I see a [ZH-E8L]https://www.zhonghangled.com/en/Download/LEDcontrolsoftware/controller for them, but as far as I can tell it's not possible to update the content online. Is there a controller with online support? So I could basically update the content remotely/ send some kind of a file to display?TLDR: I want a LED matrix controller that can receive data remotely (the data can be in any format) and display the data.

author: ledtester
author_rank: Super Contributor
timestamp: March 18, 2022, 03:00:38 pm
content: Quote from: WILDERNESSBAGEL on March 18, 2022, 01:30:50 pmThat company sells WIFI controllers -- go to Products > Single Color > Wifihttps://www.zhonghangled.com/en/Products/zhsinglecolor/WIFI/or build your own:https://blog.heisice.com/1169650896

author: WILDERNESSBAGEL
author_rank: Contributor
timestamp: March 20, 2022, 11:52:35 am
content: Wow I just missed that they make WIFI controllers, that's basically what I was looking for. Thanks!
LED Matrix  - Page 1
Forum section: electronics / projects

author: mathsquid
author_rank: Frequent Contributor
timestamp: July 01, 2017, 11:17:03 pm
content: I was cleaning up my workbench and shelves, and I ran across this project I built back in 2011. It's an LED matrix that is powered by two 555 timers, several daisy-chained 4017 decade counters, and some ULN2003 chips. Most of it is breadboarded, but I used wire wrapping to connect the LED matrices to the breadboard. I'm attaching a few pics and linking to a video, if anyone is interested.

author: kalel
author_rank: Frequent Contributor
timestamp: July 01, 2017, 11:33:32 pm
content: Looks great
LED Mounting - Page 1
Forum section: electronics / projects

author: Jon86
author_rank: Frequent Contributor
timestamp: June 03, 2013, 01:41:45 pm
content: Sorry to bother you guys with another LED question,But I'm looking at buying one of those cheap Star-Mounted LEDs from Ebay, and I was wondering if they need to be mounted on anything else for heatsinking? Or will the star do the job?The ones I'm looking at are 5W and 10W, could the stars dissipate that sort of power?I'm going to be building it onto a tin so I could attatch it to that if need be.

author: croberts
author_rank: Regular Contributor
timestamp: June 03, 2013, 01:55:24 pm
content: Hello Jon86You can determine this for yourself. Attach a temperature probe to the LED substrate (I suppose in your case that would be the star) and light the LED with whatever driver you are using. Note the temperature rise over ambient (room temperature) in free air. LED manufacturers will specify a max LED operating temperature for the LED (70 to 85 degrees C). If you operate the LED over that temperature one of the usual consequences is the life of the LED will be shortened from the specified 50000 hours or so according to some derating specification. You will probably find you will have to attach the LED to a heat sink. Star LEDs will probably not have mounting holes so you will have to do the attachment with thermal epoxy.

author: Jon86
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:11:30 pm
content: Thanks for the advice.I haven't bought any yet, but they're quite cheap so that shouldn't be a problem.

author: croberts
author_rank: Regular Contributor
timestamp: June 03, 2013, 02:28:05 pm
content: Hello Jon86One more point I would make. You said you would be mounting the LED to a tin. Tins are usually made of thin metal. Should you determine you need a heat sink (I think you will) remember the effectiveness of a heat sink is mainly determined by the surface area exposed to free air and the conductivity of the heat sink material. Conductivity here refers to heat conductivity but there is a parallel to electrical conductivity. In other words a thin heat sink will not be as effective given the same surface area as a thicker heat sink. You will probably find the thin tin is a poor heat sink.
LED oscillation behavior with 'BAD' or tenuous contacts - Page 1
Forum section: electronics / projects

author: RJSV
author_rank: Super Contributor
timestamp: November 05, 2018, 02:58:36 am
content: I noticed odd back and forth oscillations, between the apparent brightness with two LEDs connected in parallel, and wnen there is a tenuous connection created by using two tiny wires that barely touch. The experimental rig is simply using two batteries, for 3 volts, and a common resister of 1 K ohms. For the switch, I mounted two stranded wires facing each other, and removed all but one or two of the delicate strands, for testing. I'm assuming there are SURFACE OXIDATION effects, and possibly even some 'micro-sparking' that resembles the spark gaps of the old radio-telegraph days.Watching the LED pair flicker, I notice one LED will dominate, sometimes completely, and with this state of affairs flipping (so the other LED dominates) over about 40 seconds. I need help on the theory here. My thoughts are that the mechanical 'rubbing' and contact interruptions are creating switching frequencies up to maybe 10 KHZ, but my scope is showing some pretty nasty and fast 'hash', perhaps much higher; maybe RF content up to 10 MHZ ! So my theory is that there is sparking, on a microscopic scale, causing an effective RF transmission circuit similar to old radio telegraph circuits of 1890...Now, why the LED pair trade off in blinking, that's an interesting question. My scope showed about 50 milliVolts, of AC. The red LED pair operated at 1.7 volts, while a single LED operated at 1.8 volts. This is because the two LEDs interact, due to sharing the 1 Kohm load resister.
LED power supply for Vision Engineering Microscope (C073 LED ring light) - Page 1
Forum section: electronics / projects

author: nexus
author_rank: Regular Contributor
timestamp: October 01, 2022, 06:11:59 pm
content: Hi all,There was an old thread somewhere else on the forum about C073 right light from Vision Engineering for Lynx dynascopes.https://www.eevblog.com/forum/renewable-energy/led-driver-for-vision-engineering-lynx-dynascope-c-073-teardown/Decided to also post here since it is its own project now.The C073 ring light has 14 LEDs grouped into strings of 7. It also has a PT100 temp sensor and a 12v fan integrated into the module. If you want to drive it as intended and power all of these features, there really is no off the shelf solution except for the very expensive custom PSU from Vision Engineering. They usually sell the C073 right light + PSU combo for around $5,000 USD (this is just for the light and power supply, nothing else).I decided to design a custom power supply to fill this role. I recently got a Lynx on eBay as well as the C073 ring light itself, with no power supply.The main board is designed around the PIC16F1946. Its the most suitable PIC16 I could find in stock today.The 2 strings of LEDs are each driven by an MPM6010GQVE which is a synchronous step-down LED driver. I just used the reference schematic in the datasheet which includes EMI suppression passives.33VDC is provided by a traco TPI 180-136-M. Local 12V and 3V3 rails are accomplished on the board.Also threw in a MAX31865 to read the RTD and monitor LED temp.Also designed a custom enclosure. Send models out to PCBWAY to see if they can do it in 316 stainless bead blasted.Comments/suggestions welcome.

author: nexus
author_rank: Regular Contributor
timestamp: November 06, 2023, 06:51:23 am
content: Following up on project thread with an update; it works!Project files (BOM, gerbers, firmware) available here:https://neonkev.com/2023/11/06/vision-engineering-lynx-microscope-c073-led-ring-light-custom-power-supply/
LED project - Page 1
Forum section: electronics / projects

author: richb007
author_rank: Newbie
timestamp: June 25, 2024, 08:50:55 pm
content: Hi experts.I need a group of colour changing, controllable LED's to be controlled by an App.Each needs to flash, cycle, change or stay different or the same colours, individually or as a group.https://www.aliexpress.com/item/1005006760854123.html?spm=a2g0o.cart.0.0.346a38daJgpcqe&mp=1The 5050 seems like the one i need as I have them in my pc lighting.I think i need a LED controller but cant find one small enough?A Bluetooth modulehttps://www.aliexpress.com/item/1005007053264830.html?spm=a2g0o.cart.0.0.346a38daJgpcqe&mp=1A rechargeable battery to last as long as possible and to be as small as possibleEverything needs to be as tiny as possible as they need to fit into well under 10mm sq and be as thin as possible.Then i need to the PCB. i think?Then i need the App to control the whole thing but at the moment i need to know if these parts would do what i need and whether i need anything else.I have loads of other questions, such as do i need a controller or will the app be the controller? and how do i build a tiny PCB but they can wait till i know if the parts i think i need will work.Both BTooth mod and LED are 5 VoltAs you can tell i am a novice but am hungry for advise.Thanks

author: xvr
author_rank: Frequent Contributor
timestamp: June 26, 2024, 12:48:39 pm
content: The ESP32 series is power hungry. And it powered from 3.3V (not 5V).QuoteIf you use rechargable battery you need a charge controller.QuoteThis is very challenging task
LED project - Page 1
Forum section: electronics / projects

author: richb007
author_rank: Newbie
timestamp: November 02, 2024, 06:42:15 pm
content: Hi ExpertsCan anyone advise on whether this is possible and if so where to start getting it made.Circuit board to operate a group of app controlled colour changing LED'sThe complete product is made of several individual colour changing LEDS working as a group.The circuit board operates a small RGB LED system with individual controls for each LED and is managed via a Bluetooth-enabled smartphone app.Each LED illuminats a thin layer of plastic alowing them to change colour as a group or individualyIt uses a rechargeble battery and is optimized for longevity on a single charge, ideally 4-5 hours.The app will allow the LEDS to change or cycle colour on user request.The product will include a wireless charging pod for each LED in the groupThe board is ultra-compact, ideally under 5mm x 5mm, as thin as possible, and may include the following components:1. RGB LED: Positioned for maximum light diffusion, allowing color changes and flashing sequences.2. Bluetooth Controller: Enables wireless control over color changes and flashing sequences from a smartphone.3. Microcontroller (MCU): Manages individual LED settings and coordinates group functionalities.4. Rechargeable Battery: Thin, lightweight Li-Po or thin-film battery to power the LEDs.5. Power Management IC: Regulates charging and manages battery efficiency, with charging contacts designed for a low-profile fit.I know its a long read but any advise is welcomeCheersR

author: Benta
author_rank: Super Contributor
timestamp: November 02, 2024, 08:15:00 pm
content: Just use a WS2812 or similar.https://cdn-shop.adafruit.com/datasheets/WS2812.pdf

author: Andy Chee
author_rank: Super Contributor
timestamp: November 02, 2024, 08:50:52 pm
content: It sounds like you want your RGB LEDs to behave like a WS2812 light strip, BUT you want the LEDs to be individually powered and communicate wireless?

author: richb007
author_rank: Newbie
timestamp: November 02, 2024, 08:57:19 pm
content: Yes thats right,From the app i will be able to make all in the group a single or multicoloured.my main concern is the size, and mainly the battery size.i have seen the LEDs, and the chips for Btooth and they will fit, its battery im worried about

author: Andy Chee
author_rank: Super Contributor
timestamp: November 02, 2024, 09:27:03 pm
content: Well let's do some energy consumption budget calculations:According to the WS2812 datasheet, Red 12mA, Green 12mA, Blue, 12mAMicrocontroller, maybe 5mABluetooth module, maybe 30mASo you're looking at a battery size of around 350mAhhttps://www.ebay.com.au/itm/335559843441?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=wm03nsyzrea&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

author: Kim Christensen
author_rank: Super Contributor
timestamp: November 02, 2024, 11:45:40 pm
content: Quote from: richb007 on November 02, 2024, 06:42:15 pmIs this a typo?
LED Protection Datasheet Current Defintions - Semiwell PLEDxxS  - Page 1
Forum section: electronics / projects

author: sleemanj
author_rank: Super Contributor
timestamp: September 16, 2025, 01:56:31 am
content: Here is a datasheet for an LED protection device:https://www.lcsc.com/datasheet/C42413363.pdfIt lists for each variant an value for IHISand IT@VTBut what it doesn't do is define what these currents are.As best I can guess, IHis probably the minimum current to hold it in the "on" state, and IT@VTis I assume the maximum current that it can pass when it's in the "on" state (with VTbeing I assume the effective on state forward voltage), but I can't think what ISmight be.Anybody know?

author: thm_w
author_rank: Super Contributor
timestamp: September 16, 2025, 02:01:22 am
content: Can you find the same part from another major manufacturer and then it will be clearly specified?You can see a diagram here:https://www.unictron.com/news/snapback-tvs-diode/edit, here you go:https://www.littelfuse.com/assetdocs/led-protectors-pled-6-9-13-and-18-datasheet?assetguid=7009dc96-df2e-4194-8a38-270e4ae4141f

author: sleemanj
author_rank: Super Contributor
timestamp: September 16, 2025, 02:24:24 am
content: Unfortunately that datasheet doesn't define ISeither.Ok, it kinda defines it, in that it's depicted on the V-I chart (as it is on the datasheet I posted now I zoom in and look hard). Seems to be the maximum current through the device up tot he point it breaks down and "snaps back" as that other link describes it.
LED Retrofit lamp - Power Factor - Page 1
Forum section: electronics / projects

author: steve30
author_rank: Frequent Contributor
timestamp: November 19, 2013, 01:56:58 pm
content: I just bought a Philips CorePro 5W LED GU10 lamp. Seems quite nice.But it has a rated power factor of 0.5. Its rated current is 40mA, at 240V.This 40mA multiplied by 240V (ish) is approx 9.6W. Now, I'm wondering two things:1) Is the 5W just the LED power and the other few Watts the loss in the driver?or 2), Is the 5W the true power, and the approx 9.6W the apparent power? Because (5W/0.5 = 10W).I'll try and do a bit of measuring later on and see what I get.Thankssteve30

author: qno
author_rank: Frequent Contributor
timestamp: November 19, 2013, 08:47:02 pm
content: With AC one cannot simply multiply Voltage and current.It is V x I x cos (fi)To accurately determine the power you need to know the phase relation between the current and the voltage.
LED RF Wireless Dimmer and Timer - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: May 13, 2015, 10:09:24 pm
content: Looking for an RF dimmer and timer to control my aquarium LEDs, 12V at 2.5A in total for full brightness. Have looked on Amazon and there are two RF remotes but have abysmal reviews.If nothing reliable exists I was thinking of an Arduino project: Arduino module + 433 MHz RF transceiver + LM2679 switcher to provide the dimming + DS1307/DS3231 RTC to provide the timerI am not sure if the Arduino would be a clever idea, for starters how do you make a tiny and sleek remote?Edit: Damn something existshttp://www.ebay.co.uk/itm/315Mhz-Wireless-Remote-Control-RF-DC-5V-Transmitter-Receiver-Module-for-Arduino-/231418644091?pt=LH_DefaultDomain_3&hash=item35e1a0467b
LED Sign from London Bus Stop - Page 1
Forum section: electronics / projects

author: owl_uk
author_rank: Contributor
timestamp: January 20, 2014, 06:08:15 pm
content: I found an LED sign from a london bus stop on Ebay. I thought I would be cool to put it on the wall of my lab and write things on it by the internet. Photo below. I'm in the process of reverse engineering it and connecting it up to a micro to display some messages. I've found a couple of things I could do with a little help on.It seems to have a control board, then a load of row driver boards, which drive a line of LEDs all at once, then the boards with the LEDS attached are column drivers.They drive 8 leds at a time from a DFF which is in-turn driven from a serial shift register. The column driver boards are connected to the LEDs which are arranged into 5x7 matriciesThe column driver is here. Can anyone confirm:1 - The chip marked HC574 - I assume this is a cheap generic 74HC574- is this likely to be the case?2 - The long yellow things - My guess is that these are resistor packs being used to limit/control the LED current. Is this what resistor packs used to look like?

author: P_Doped
author_rank: Contributor
timestamp: January 20, 2014, 06:20:37 pm
content: 2 - The long yellow things - My guess is that these are resistor packs being used to limit/control the LED current. Is this what resistor packs used to look like?These are SIP versions of resistor packs where there are N-1 resistors all connected to the pin with a dot on it. They are used when you need pullup or pulldown resistors.

author: David_AVD
author_rank: Super Contributor
timestamp: January 20, 2014, 09:10:04 pm
content: Quote from: P_Doped on January 20, 2014, 06:20:37 pmThe SIP versions are also available in "non-bussed" configuration. eg. 4 resistors end to end in an 8 pin SIL package. An odd number of pins should exclude that possibility of course.
LED signal fixture - Page 1
Forum section: electronics / projects

author: tszaboo
author_rank: Super Contributor
timestamp: June 19, 2019, 01:09:43 pm
content: Hi. I'm searching for a signal lamp, to signal crane operators if a loading of something happened correctly.It is outside harsh environment, seaside, IP69K rated, industrial, high quality, safety critical, battery powered.I have something like this in mind:https://www.signal-tech.com/product/file/10893.png&width=500&height=334Do you know any manufacturer who makes these kind of LED fixtures that can be bought off the shelf?
LED spec in lm and mcd - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: May 01, 2024, 04:47:24 am
content: Why differnt LED brightness specification are in(a) Luminous Flux (lm) (b) Luminous Intensity (mcd)?How to compare and choose the brigher LED for same current consumption?Many thanks

author: Nominal Animal
author_rank: Super Contributor
timestamp: May 01, 2024, 06:35:18 am
content: Given luminous intensity \$I_v\$ in candelas (1 cd = 1000 mcd) and solid anglein steradians (full sphere being \$4 \pi\$, half-sphere \$2 \pi\$ steradians), luminous flux \$\Phi_v\$ is \$\Phi_v = I_v \Omega\$.For an omnidirectional (spherical) uniform bulb, luminous flux is about 0.012566 lm/mcd.For a bulb emitting light at uniform intensity to half-space, luminous flux is about 0.0062832 lm/mcd.For LEDs, luminous intensity varies depending on the direction, and luminous flux is actually an integral of the direction-dependent luminous intensity over all solid angles (all possible directions).Technically, candelas describe the (wavelength-weighted) power emitted by the light source in a particular direction. Solid angle describes how much of all possible directions the light source covers (the surface area of an unit-radius sphere), and luminous flux is the total amount of (wavelength-weighted) power emitted by the light source.Thus, when listed for a LED, the figure in candelas is either a peak or average intensity, and varies depending on direction; and the flux in lumen is the overall amount of light it emits considering all directions. The ratio of the flux to intensity, \$\Omega = \Phi_v / I_v\$, is a rough single-number description of the solid angle it emits light to, or "spread", if you will.

author: Psi
author_rank: Super Contributor
timestamp: May 01, 2024, 06:43:17 am
content: Put simply..Lumens (lm) is the amount of total light emitted in all directions all added together.The LED Angle does not come into it. You can compare one leds lumens to another's lumens to determine which one is more efficient (more light for same power in)cd/mcd is the amount of light that hits a fixed point directly in front of the LED. So a narrow angle LED (led with lens) focuses and concentrates its emitted light into a beam. eg The same LED die with a 20deg lens will have a much higher mcd than that led with a 100deg lens even when they are both the same lumens.You can only compare a mcd values between LEDs with the same angle.You can use these online calculators to convert mcd + angle into lumens and backbut be aware the conversion is not perfect, there is some error.https://www.rapidtables.com/calc/light/mcd-to-lumen-calculator.htmlhttps://www.rapidtables.com/calc/light/lumen-to-mcd-calculator.html
LED Strip Lights - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: January 26, 2014, 11:06:43 pm
content: I am designing a circuit to power a 2x roll 5m strip of LED lights, i designed a board to power the lights from a power supply and also the arduino chip etc. The board isn't fancy just effectively acts as a sort of distrubution board to power the arduino and pass onto the strip lights.Problem I am looking out now is that from what I can see each of these rolls draws 10amps, so technically thats 20amps. I have had these running from a laptop before and seemed to work ok.If I use say a 4 amp psu would this power the lights but just dimmer than normal? or would I need to find some kind of 20a psu to power these safely?

author: ovnr
author_rank: Frequent Contributor
timestamp: January 26, 2014, 11:39:41 pm
content: For one, I doubt your LED strips actually draw 10A per 5M length? I've got one with 60x 3528 LEDs per meter, and that eats somewhere between 1 and 1.5 amps for 5 meters (I forget exactly what).Also, when you say you've had them running from a laptop, what do you mean? From the USB port? The laptop PSU?Lastly: Using a 4A PSU to drive a 20A load will likely blow up the PSU or send it into overcurrent mode, and turn off. If you really have a 20A LED load (presumably with ballast resistors) that you need to drop to a lower level, you need to adjust the voltage it gets until they consume the desired current; merely using an insufficient PSU will not help you*.(*: If you actually have a current-regulated PSU, that will obviously work. I doubt you do.)

author: Towger
author_rank: Super Contributor
timestamp: January 27, 2014, 01:00:16 pm
content: As per my other post today, the 5050 5m 300 LEDs rolls draw around 3A (or a little over) at 12V. The only type I know of where the sellerssaydraw 10A are the double row 5050 5m 600 LEDs rolls or 120 LEDs per meter.So depending on your type of LED strip, you PSU may be OK for 2 rolls or just 1 roll, providing it is 12V (or not much higher) and can actually deliver 4A continuously.
LED Strobe Light - Page 1
Forum section: electronics / projects

author: nes999
author_rank: Contributor
timestamp: January 08, 2017, 01:49:38 am
content: I want to make a box with a few different colored LEDs for a special needs family member. This is my first time dealing with small electronics. I am having a total of 32 LEDs. The most on at one time is 16. However there will be rapid flashing between colors.Do I plan for enough power for all 32 LEDs or for the max of 16 that will be on at one time?If it matters I am using an arduino to control the flash patterns.

author: ebclr
author_rank: Super Contributor
timestamp: January 08, 2017, 02:09:09 am
content: In the worst case scenario 500 ma will be enought, but probably you will be in 200 ma range

author: ajb
author_rank: Super Contributor
timestamp: January 08, 2017, 06:00:02 am
content: There's no need to design for conditions your device is never expected to see. Whether your expected conditions are accurate to the intended usage scenarios is another question, though. "Rapid flashing" isn't a concern as long as one color is turned off before the other color is turned off, but even a brief period of both being on may be able to be covered by bulk capacitance.What sort of LEDs are we talking about here?

author: BrianHG
author_rank: Super Contributor
timestamp: January 08, 2017, 01:28:58 pm
content: For my recent flashing led project, I used this cheap SOT-23 mosfet: BSS806N H6327 which I drove right from my PIC's IO with a gate drive of 2.5v or above, and had a series resistor to the power LED I was using.Though in my case, I was sinking a 2 amp pulse to strobe illuminate a room, you will only need to use a fraction of that with normal LEDs.

author: nes999
author_rank: Contributor
timestamp: January 08, 2017, 05:30:18 pm
content: Quote from: ajb on January 08, 2017, 06:00:02 amAttached below is the full data sheet for the ones I bought.I know those are really bright, However what they are using now are construction strobes and I'm afraid if they want from that level brightness to a dimmer LED he will not use it. I figured I could make this, and if it works try making a dimmer one also.I'm really glad to see that I only have to have the battery sized for what's on at the moment. That means I only need to supply it with a 12v battery source, and of course appropriate resistors.http://cloud.tapatalk.com/s/587275821a089/YSL-R531Y2C-A13.pdf
led touch screen - Page 1
Forum section: electronics / projects

author: jaRON
author_rank: Contributor
timestamp: April 25, 2011, 04:49:57 am
content: do you know were you can get a led touch screen like in the ipod touch?

author: alexwhittemore
author_rank: Frequent Contributor
timestamp: April 26, 2011, 02:05:17 pm
content: Sparkfun sells a bunch of LCD/touch sensor packages, some even pulled from commercial devices like the PSP. They can be hard to drive/use, but there are some popular ones that have a fair bit of hobbyist documentation on the internet. Here's anall-in-oneunit, and here isjust the touch panel from a psp, to lay over your own LCD. That second one also links to a touch screen tutorial you might find helpful. Note both of those are resistive, so no multi-touch.Capacitive screens (like the kind that can do multitouch) are newer and more complex, so I'm not sure about finding them or info on how to interface them in the hobbyist realm.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 27, 2011, 12:37:25 am
content: Color LCD Monitor For Hobbiest, squeezee suggested E'Go china
LED Traffic Light - Page 1
Forum section: electronics / projects

author: matematik7
author_rank: Newbie
timestamp: December 04, 2016, 06:44:21 pm
content: Traffic lights are all around us, and they seem simple enough but are they really? Real traffic lights can be a very complicated system because it requires sophisticated control and coordination for smooth and safe traffic.The traffic light I made is much simpler. My sister works in a kindergarten where kids needed a simple traffic light for when they are riding their bikes on the playground.The traffic light uses some cheap LEDs from China, a step-up converter and an Atmel attiny841 microcontroller to change the light from red to green at a programmed interval.More info:https://domen.ipavec.net/en/traffic-light/

author: Zero999
author_rank: Super Contributor
timestamp: December 04, 2016, 07:17:34 pm
content: Very good.I noticed you said about the green LEDs being dimmer than the other colours? Well that's because they're cheap old GaP LEDs. For a higher brightness you need InGaN but they have a higher forward voltage.
LED volt and amp meter  - Page 1
Forum section: electronics / projects

author: awesley
author_rank: Newbie
timestamp: February 08, 2015, 03:04:50 am
content: Hi, I'm a mechanical engineering student and I have a project where we have to design and build a motor that runs on compressed air. The volts and amps produced by the motor are to be measured via a dynamometer connected to the flywheel of the motor. The dynamo drawing has the specifications: speed=5300 RPM, voltage=10VDC, voltage=12VDC(no load), max current=2.4 amps. The professor said that the dynamo will be connected to 5 load switches that have resistors connected to them. I'm mechanical, so I have no idea how this works.The design of how to measure the output of the motor has been left entirely up to the students. Currently, my design is to just wire the dynamo up to analog volt and amp meters. I was wondering what it would take to wire up a line of LED's to use as a meter to measure the volt and amp output of the motor. Can anyone point me in the right direction?

author: Seekonk
author_rank: Super Contributor
timestamp: February 08, 2015, 09:17:23 am
content: This is probably not what your professor wants because it doesn't require you to do any thinking. On ebay you can get a power meter, search 90V 10A power meter, get one that says it can be externally powered because your motor won't supply enough voltage. It will read out volts, amps and watts directly for less than $15.

author: SL4P
author_rank: Super Contributor
timestamp: February 08, 2015, 12:09:37 pm
content: Kinda odd to ask Mech Eng students to design an electrical monitoring circuit...??Compressed air in, dynamo (generator) out - into a number of switched load resistances.If you know the characteristics of the 'motor', the energy transfer characteristics of the (gearing?, shaft and) dynamo - then all you need to measure is the output voltage, and the current drawn when the different load resistors as they are switched in.It's a DC circuit - the rest is up to Ohms law.Maybe to spice it up - you can add a fuse - in case the load draws more than 2.4A and cooks the dynamo.(e.g. two or more resistors 'switched in' being greater than the max available current from the generator)

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 08, 2015, 02:56:43 pm
content: On eBay there are lots of dual LED panel meters that read 0-99.9 Volts and 0-9.99 Amps. They are of Chinese origin and are very cheap (less than 3 GBP inc delivery).Some may work without needing a separate supply, depending on how low the supply is (typically working down to 4.5 Volts from memory). I use one in a bench power supply and it works great, although the plastic escutcheon was poorly designed, as the mounting clips were fouled by the electronics! A file and superglue sorted it...SJ
Led x-mas lights  - Page 1
Forum section: electronics / projects

author: VoidsWarranties
author_rank: Contributor
timestamp: November 25, 2016, 01:49:50 pm
content: This isn't a question but if anyone wants to make a light show with AC led Christmas you can run half of the strand with DC and if you reverse the polarity you can run the other halfSent from my iPhone using Tapatalk
LEDs with PLCs for Aesthetics - Page 1
Forum section: electronics / projects

author: am1
author_rank: Contributor
timestamp: September 05, 2024, 08:22:31 pm
content: Hi all,I have a project that requires me to add some LED underlighting to my device (device uses a B&R X20 system). The lighting will need to be my synced with the HMI screen (lights turn on/off when HMI wakes/sleeps respectively). It will also potentially be integrated further with the controls in the future to the flash when certain device conditions are true. I will need either long strip leds to wrap under my device or something bright enough to illuminate from under. I have an X20DS438A module that has a digital output of 24V @ 0.25A that I hope do use for the lights. All this being said, are there any lighting options anyone has worked with or would recommend for this kind of application? Not sure where to start looking as I need purely aesthetic lighting and not the standard industrial PLC type leds. Thanks in advance!

author: Buriedcode
author_rank: Super Contributor
timestamp: September 06, 2024, 03:28:23 am
content: Are you after different colours? Because if its just one colour, and you require on/off and perhaps coarse brightness control, then it gets a lot easier. A 12V LED driver with dimmer input should work - that dimmer input could be controlled by the HMI screen wake/sleep signal, and for any other controls.

author: ajb
author_rank: Super Contributor
timestamp: September 06, 2024, 02:54:39 pm
content: Even if multiple colors are required, something like a strip of RGB LED tape can easily be controlled by PLC outputs, with or without PWM. You might need more than 0.25A, but an SSR can solve that. There are systems of aluminum channel and snap-in lenses you can cut to length and then install the tape into for protection/diffusion/aesthetics if needed (example). There are also plenty of ready-made rigid LED strip lights, though fewer in RGB.If you need dimming and can't or don't want to use PWM, there are LED drivers with analog dimming inputs -- often 0-10V, but some at lower voltages -- for both constant voltage and constant current drivers.
LED’s - Page 1
Forum section: electronics / projects

author: BernieX
author_rank: Newbie
timestamp: January 22, 2021, 04:01:47 pm
content: This may be too simple for the group but any input would be terrific! I build all types of Sci-FI models and during the builds I light various aspects using LED’s. I need a generic circuit I can use for many models that will randomly flash at least 6LED’s...8 would be even better. I would like the speed to be adjustable and more than one LED flashing on at the same time. The random effect would be for example: the look of indicators on an operating computer in a console or the randomly flashing navigation lights on the outside of a space ship. Operation voltage of 9-12vdc. Lastly it is possible that I may not need every LED the circuit will operate so one or two may not be connected. Jensen the universal nature of the circuit and being able to use it for many different model projects. Thank You for any help.BBbjb628@gmail.com

author: Peabody
author_rank: Super Contributor
timestamp: January 22, 2021, 06:12:47 pm
content: It sounds like this is something a microcontroller would be good for. Do you have any experience with Arduinos? How much room would you have in the typical model for the battery and electronics?

author: bob91343
author_rank: Super Contributor
timestamp: January 22, 2021, 10:49:41 pm
content: You could run a group of 555 or 556 chips with different frequencies.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 22, 2021, 11:58:30 pm
content: There are LEDs and they cost almost nothing, which flash themselves in different colors randomly. There are fast flashing, there are iridescent colors. On Aliexpress, you will find tons of them at the price of $1 for half a bucket.
leeson feedback principle with two port resonator - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: April 21, 2025, 08:04:41 pm
content: Hello,In a two port resonator we have S11 minimal in resonanvce while S21 is maximal,at resonance phase is zero.what do we do with the S11 as feedback?what is the logic the the leeson mechanism?Thanks.https://www.iaeng.org/publication/IMECS2014/IMECS2014_pp733-740.pdf

author: john23
author_rank: Frequent Contributor
timestamp: April 22, 2025, 06:56:21 am
content: UPDATE:Hello,I want to created the system.From the articles I see that we input noise to the amplifier then the noise gets amplified and we compare thefeedback from the output(s11) to the noise.few questions:1. where is the comparation of the feedback in the topology below.I cant see here the feedback.2. at resonance we have phase of 0,what is the effect of the feedback here?Thanks.

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: April 23, 2025, 06:54:05 am
content: There is no logic behind Leeson mechanism, it is just a good observational guess — like Max Planck's.Its minimalist description is: "an oscillator seems to rotate noise by -20dB/decade."Quote from: john23 on April 21, 2025, 08:04:41 pm
Lemo Triax Connector Used with Rohde & Schwarz Equipment - Page 1
Forum section: electronics / projects

author: ocw
author_rank: Regular Contributor
timestamp: May 22, 2021, 04:10:02 am
content: I am looking for the part number for the Lemo Triax connector which would plug into Rhode & Schwarz equipment such as their ETL and EFA. It is used on the end of their cables 2068.9187.00 and 2067.7451.00. I cannot find its number anywhere.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 22, 2021, 08:21:05 am
content: You have a picture of the mating part ?

author: ocw
author_rank: Regular Contributor
timestamp: May 22, 2021, 01:12:48 pm
content: Attached is a combined picture showing the connectors that I want to connect to. On each, I want to connect to the audio jack. What connector will connect to them? Remember, they are three conductor jacks meant for triaxial cables. The equipment shown are Rohde & Schwarz EFA, DVMD and ETL.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 22, 2021, 01:39:28 pm
content: Sorry, I am not familiar with this instrument.These connectors look like LEMO Triax 1SLEMO size 1S, TRIAXThe part number is: ERD.1S.650Take also a look at the LEMO ERN series.I have also been successful in getting answers from LEMO, asking them by email.

author: ocw
author_rank: Regular Contributor
timestamp: May 22, 2021, 02:00:55 pm
content: It looks more like 0S size. I need the connector to plug into the shown jack--with a female center pin. I see some possibilities. However with their limited availability and relatively high price I do not want to order the wrong one.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 22, 2021, 06:52:55 pm
content: You can easily measure the diameter on your R&S connectors and find out if it is 1S or 0S size.The LEMO datasheets are very clear on this.I have used many triax connectors but not this one
Lens of IR projector in Microsoft Kinect and Asus Xtion - Page 1
Forum section: electronics / projects

author: canol
author_rank: Contributor
timestamp: March 17, 2014, 04:23:53 pm
content: Hello, I am doing Kinect/Asus Xtion hacking projects. I need to use these devices without their case so that I can mount them to my own device. My question is about the lenses (or protectors, whatever you call them) in front of the cameras and IR projector. As you might know these devices have 3 lenses on them: One for IR projector, one for IR camera and the last one for RGB camera. My question is about the lens in front of the IR projector:As you can see from the images above, the lens in front of IR projector of both devices has a different reflection behavior compared to other two lenses (it is more subtle in Asus Xtion compared to Kinect). It has a more greenish reflection. It is clearly a different material or has some kind of filter.I wanted to know what this material is or what filter it is and what it is used for? What would happen if I use these devices without this lens? Does anybody have an idea?

author: electrodacus
author_rank: Super Contributor
timestamp: March 17, 2014, 05:32:42 pm
content: Not sure. I may be wrong.None of them is a lens you have probably an IR filter to stop IR entering the RGB camera.On the IR camera and projector is just a piece of plastic since glass will stop part of the IR and that plastic is mostly to protect the camera and projector from dust or cosmetic it probably dose not have a role.

author: canol
author_rank: Contributor
timestamp: March 17, 2014, 05:58:46 pm
content: Quote from: electrodacus on March 17, 2014, 05:32:42 pmThanks for your answer. Yeah I wasn't sure if I should call them lens or something else. The weirdly reflecting plastic thing is in front of IR emitter not in front of RGB camera so I think it should be something else. Here is an illustration to show the parts:

author: electrodacus
author_rank: Super Contributor
timestamp: March 17, 2014, 07:16:37 pm
content: Yes it seems to have a green tint the IR filters have a purple tint and it will not make sense anyway in front of the IR emitter.Not sure what it is but if is necessary can you just get that out and use it?I'm not familiar with Kinect. I wanted to get one to do tracking and make animation with Blender 3D but never got the chance.