Which (LED) lights for your lab / workspace? - Page 1
Forum section: electronics / general

author: niels007
author_rank: Contributor
timestamp: November 04, 2018, 01:42:50 pm
content: Hi there!I need to light up my hobby / office room, preferably without the use of fire..Mainly to work pleasantly without eye strain and also to record some video.But I wonder how to do it. I have two desks, I can have some led armatures hanging from the ceiling for each desk. But I'm also thinking about just attaching 4 or so led armatures / panels to the ceiling so the whole room is pretty uniformly and brightly lit. The room is only 3.5x3.5 meters.Just to mess with I got some ultra cheap armatures ( Dutch alert:https://www.ledpanelendiscounter.nl/led-batten-armatuur-40w-120cm-4000k.html). They give off a LOT of light, which is quite pleasant but they flicker and humm ever so slightly. The camera sees the flicker, I don't think I do, but perhaps this still causes a bit of eye strain compared to higher end panels.How do you guys uniformly light your rooms brightly? What (flicker free) panels / armatures could do the trick? I realize I may have to fork out a bit of actual money for this, but that's fine..

author: cdev
author_rank: Super Contributor
timestamp: November 04, 2018, 01:50:37 pm
content: You could power your LEDs with a linear DC supply instead of a switcher.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 04, 2018, 02:00:44 pm
content: 100W LED modules are $10 or so each. Get the warm white ones from Amazon and run them at well below their rating to make them last. Old CPU heatsinks work nicely to keep them cool and you don't need the lens unless you want a focused beam.

author: rdl
author_rank: Super Contributor
timestamp: November 04, 2018, 02:02:01 pm
content: I like these so much I've added a third one since this photo. The picture is much darker than reality, the camera over compensated and I didn't bother to fix it. I don't think it would be too hard to hang them, or one of them, facing up for much nicer diffused light.https://www.eevblog.com/forum/reviews/desklab-lighting-tips/msg1273977/#msg1273977

author: nctnico
author_rank: Super Contributor
timestamp: November 04, 2018, 02:02:36 pm
content: I'd look at lamps made by Philips and select based on licht temperature and CRI. I have these CFL lamps for my workspaces in armatures with electronic ballasts:http://www.lighting.philips.nl/prof/conventionele-lampen-en-buizen/fluorescentielampen-en-starters/tl-d/master-tl-d-90-de-luxe/928044595081_EU/productThe light temperature is 5000K and the CRI is 92. The LED lamps you linked to seem like cheap rubbish to me to use over a bench (yellow-ish light and low color rendering index) and the efficiency isn't very high either.

author: Crazy_Pete
author_rank: Regular Contributor
timestamp: November 04, 2018, 02:04:48 pm
content: Something i have found to be essential is to use the Monolithic Cree LEDs. (I am sure there are other brands now.) But you want a single point light source inside the LED (as opposed to lights that have several LED chips on the inside.) The multiple LEDS create shadows and artifacts that seem to be most obvious whenever you want to do close in hands on work.Also make sure that you get true white (5000K) LEDs for your lab or you will might have trouble reading resistor codes. (Seriously)Mostly we have simply installed monolithic LEDs lightbulbs in place of the regular ones. Dimmers and transformers in the line are what cause LEDs to flicker (usually). Be careful of "dimmer switches" they can not only cause the LEDs to flicker but can reduce the life by 90%. We have a real problem here in that the guy who remodeled the house put step down transformers and installed 50 watt halogen bulbs for the main lighting system. (Same guy that started all the electrical fires i mentioned in a previous post.) It seems he buried the transformers behind the walls and "I really don't have any idea where i put them. They are mudded in behind the walls somewhere." So i have to figure out how to get a magnetic field detector and find them. Aggggghhhh!!!BTW do any of you guys have any idea how to find these transformers? They are about 30 years old and probably going to catch fire sooner or later.I know it is not his fault, his mother was an innocent victim of a war time injury. But i told him "Mark, you deserve infinite compassion because it is not your fault that you are retarded. It is a very sad, very wrong, but very true fact of history that you became retarded in order to save the world from Hitler. But Mark, you have to meet us halfway, you have to remember, it is also a very sad, very wrong, but very true fact of history thateverybodyliked Hitler... when he only killed retarded people."Thanks allPeter

author: cdev
author_rank: Super Contributor
timestamp: November 04, 2018, 03:02:03 pm
content: You need an electromagnet and an audio amplifier, one thing that would work well would be a tracer used for following wires, such as a two part device I have (a now-discontinued Velleman VTTEST 11b, photo below) which inserts a warbling tone into wires, and has a probe which you follow the tone in. Its actually a branded version of a ultra cheap device available on ebay for much less. Any of them would work well.Especially when distinguished from other wires with this kind of device's unmistakeable tone the probe should be able to follow the halogen wires to the transformer whose hum you should then also be able to hear.You can also take a ferrite rod and make a quick magnetic field probe by wrapping as many turns of wire around it as works for you and then connecting the coil to the input of an audio amplifier, but that leaves you without the tracing signal injector.I would just get one, as they are very helpful whenever you are pulling cables.Note, take care not to short out the cable when you are attaching the tracer. Hopefully this person was smart enough to put any switches on the other side of the transformer, but they may not have. Keep in mind the wiring is quite probably unsafe and in need of complete replacement.

author: rich
author_rank: Frequent Contributor
timestamp: November 04, 2018, 03:56:37 pm
content: I'm starting to unpack my lab from 18 months in storage into a new dedicated room so have been thinking a lot about lighting recently... I'm looking to use LED panels (600x600mm) as found in commercial office suspended ceilings and have ordered 2 panels for testing before committing to 4 or 5 more. Dimming and colour are important for me - bright for fine assembly work and dimmer for programming/CAD/office/night.@Crazy_Pete maybe a thermal camera to find the warm transformer hotspots in the wall?

author: jmelson
author_rank: Super Contributor
timestamp: November 04, 2018, 04:55:37 pm
content: I made my own, and put them in the kitchen.See:http://pico-systems.com/Lighting.htmlI did it mostly for energy efficiency, but the results have been quite good.Jon

author: Red Squirrel
author_rank: Super Contributor
timestamp: November 04, 2018, 06:45:02 pm
content: Maybe I'm old school but I really like the type of light that T8 bulbs put off and like working with those fixtures. It's a nice bright and even light and they are fairly easy to install and because of their long shape they don't cast many shadows. I always get cool white or daylight. If you get daylight it may even help with seasonal depression. (I discovered last year that I'm susceptible to that so been using daylight bulbs all over my house now). Currently I only have a single lamp stand in my home office/lab so I'll probably be putting in two T8 double fixtures. However I am starting to wonder if I should look into LED. LED is good too but my issue with it is that lights are hit and miss, and typically they are built into the fixture which makes it hard to choose colour temperature as you basically take whatever you get. Some come in daylight, some come in warm white, etc. But you can't really pick on a per fixture basis. The fixture you like might come in the wrong colour for example.Another thing that's crossed my mind is to do LED strips. Typically those will run on DC and come in various colours. Though do those do PWM internally or are they constant lit from the 5v? I try to avoid anything that flashes as I can actually notice it, and if I do plan to record anything like vlogging or what not, it could be an issue too.

author: Gregg
author_rank: Super Contributor
timestamp: November 04, 2018, 07:01:36 pm
content: Crazy_Pete,QuoteThere are several ways to locate transformers in your scenario. The low voltage tolerant toners as suggested by cdev may work to get you close; turn off the power first and try one of the toner leads to a good ground and the other to one or possibly both of the low voltage conductors; this may not work if the mains wiring to the transformer does not have a grounding conductor however. Using a toner is more of an acquired art than a science.Another approach is with a mains tolerant toner designed to find circuit breakers, but start at the breaker or other mains feed to the transformer and try to find the transformer end. Amprobe used to make some good ones of these and there are the ones used to find wiring buried in the ground.An inexpensive metal detector may be your best solution; 30 year old transformers should have substantial iron in their cores.On the other hand, 30 year old quality made in USA transformers probably are very reliable especially compared to imported SMPS units. The connections to the transformers by pyro-Mark are probably the most suspect. In any case it is now and 30 years ago was against code to install any inaccessable mains electrical connections. I’m sure it wasn’t done with a permit and your insurance may not pay if the non-code installation causes a fire.I have yet to find one of the so called stud finders that reliably will find wiring in a wall; even though some of the more expensive models claim they can.The Bosch D-tect 150 could find the transformers but is very fiddly to use; you would have to narrow your search with other methods.

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2018, 08:26:33 pm
content: Audio amplifier and the winding core from an industrial 24VAC contactor will work. run without the core to get a rough sense of location with the light turned on, and when you get close turn down the volume and put the E shape part of the core in, which increases sensitivity and focuses to the area between the open parts of the core.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: November 04, 2018, 09:05:20 pm
content: To detect flicker, wave your hand rapidly with open fingers in front of the light. If you see multiple solid images of your fingers, it's flickering.LEDs are actually one of the worst light sources for nuisance flicker due to their short persistence, although this is due to bad driver circuits rather than the LEDs themselves. Ones to avoid are the type that looks like a traditional light bulb with LED 'filaments' in it. Also the direct mains COB LEDs.Even if the flicker is not noticeable it can cause headaches since the eye muscles try to keep up with it. This is especially true on half wave supplies at 50/60Hz. At 100Hz or higher (fullwave rectified) it's generally too fast for the eye to respond to.Best solution for flicker free bench lighting is a true DC supply to LEDs. Or, old fashioned bulbs.

author: Red Squirrel
author_rank: Super Contributor
timestamp: November 04, 2018, 09:36:18 pm
content: Why is it so hard to drive LEDs with solid DC anyway? Since LEDs are constant current driven and not constant voltage driven can't they put a shunt and then increase/decrease voltage based on the current going through it?

author: nctnico
author_rank: Super Contributor
timestamp: November 04, 2018, 09:40:27 pm
content: Quote from: IanMacdonald on November 04, 2018, 09:05:20 pmNot just that but fast flickering lights also attrack insects. For my bathroom LED light controller I have opted to implement current sources instead of PWM so the lamps don't flicker at all.

author: GreyWoolfe
author_rank: Unknown
timestamp: November 04, 2018, 10:03:56 pm
content: Quote from: nctnico on November 04, 2018, 02:02:36 pmI am using Envirolite 6 bulb fixtures over my workbench. Huge amount of light, 5000K and 10,800 lumens per fixture. $130 USD a fixture through Homedepot.com. I also have 2 single bulb over my work desk and ham radio desk that work well also.

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 05, 2018, 05:50:02 am
content: I'm using led strip from ebay in aluminium channel designed for the purpose.The LED strip I use is rated to 5000K and above 90 CRI. They put out a lot of light and the colour rendition is excellent.I stuck them under the shelf above my workbench and also used them to make a 300mm x 300mm panel light that hands over my shoulder like an operating theatre light.LED strip (I used 5000k 12v stuff):https://www.ebay.com/sch/i.html?_nkw=White+5630+LED+Strip+CRI+90Channel (I used the 'U' type):https://www.ebay.com/sch/i.html?_nkw=U-Shape+Aluminum+LED

author: capt bullshot
author_rank: Super Contributor
timestamp: November 05, 2018, 06:25:25 am
content: Quote from: Red Squirrel on November 04, 2018, 09:36:18 pmIt's not hard at all. It just costs more money.

author: Red Squirrel
author_rank: Super Contributor
timestamp: November 05, 2018, 03:41:17 pm
content: Quote from: capt bullshot on November 05, 2018, 06:25:25 amWow is that really all it is, figured maybe there was more to it. Guess companies are just so cheap now and build for as cheap as possible even if just saving a few bucks.

author: jmelson
author_rank: Super Contributor
timestamp: November 05, 2018, 08:31:43 pm
content: Quote from: Red Squirrel on November 04, 2018, 09:36:18 pmGood LED drivers (power supplies) have filtering in them, so there is no mains-frequency flicker. The ones I have put in my kitchen (link above) have no flicker at all, and are really nice. You KNOW they have big caps in them, as they fade out over nearly a second when you turn the switch off.Jon

author: David Hess
author_rank: Super Contributor
timestamp: November 06, 2018, 07:19:11 am
content: I agree with Red Squirrel. Linear fluorescent tubes are what I like best because they produce little or no shadows. Even better in some cases, they can be used with a passive ballast for little or no EMI.

author: ferdieCX
author_rank: Regular Contributor
timestamp: November 06, 2018, 07:17:16 pm
content: I installed a LED stripe from Diodor under the shelf above my workbench. It gives a good light, but the switching power supply produced false triggering in my scope. The nominal operating voltage is 12 V, but the specified range is 10 - 14 V.So, I built a simple unregulated power supply with a 9 V + 9 V transformer, 2 diodes and a capacitor. The peak voltage is 12 V with less than 1 Vpp ripple. The EMI is gone

author: nfmax
author_rank: Super Contributor
timestamp: November 06, 2018, 07:33:17 pm
content: Quote from: Crazy_Pete on November 04, 2018, 02:04:48 pmA thermal imaging camera is ideal for this!

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 06, 2018, 07:37:33 pm
content: Do any of you take electrical noise into account? I've had trouble with a monitor spewing garbage all over the place. That's not great when you're trying to do careful measurements.

author: jmelson
author_rank: Super Contributor
timestamp: November 06, 2018, 08:26:21 pm
content: Quote from: Mr. Scram on November 06, 2018, 07:37:33 pmYes, A BIG problem! But, it isn't just lights doing it, it is practically EVERYTHING in the whole house!(Nearly) every wall wart, phone charger, laptop power supply, compact fluorescent, general home appliance, etc. has a switching supply in it, and most are extremely poorly designed and radiate a ton of noise.I certainly have not found LED lamps to be any worse, and at least some may actually be better than CFLs, for instance.Jon

author: t1d
author_rank: Super Contributor
timestamp: November 06, 2018, 08:31:55 pm
content: I have seen advertised newer technology, for looking behind walls... Imagining stuff. Not sure if it is sonar, or radar... There is even an app, for your cell phone (requiring a subscription, I think.) I have no idea, if they work well, or not. Maybe google?