EEVblog #307 - Lab Lighting & Measurement - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2012, 11:08:19 am
content: Dave.

author: fmaimon
author_rank: Unknown
timestamp: July 07, 2012, 01:57:11 pm
content: If you are still using a magnetic ballast, try changing for an electronic one. The lamps gives higher light output and consumes a little less power than the magnetic one.http://en.wikipedia.org/wiki/Electrical_ballast#Electronic_ballasts

author: SeanB
author_rank: Super Contributor
timestamp: July 07, 2012, 02:42:08 pm
content: True, and when the ballast dies in 14 months you just fit another ballast and leave the same lamps in the fitting. Magnetic ballasts last for decades, I have not had any electronic ballast for lighting last any more than a decade, and that one was just because the fitting was only turned on once a month for a few hours for servicing the lift. Most blow up at the 2-5 year mark, leaving the lamps in good condition.

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2012, 02:43:27 pm
content: Quote from: fmaimon on July 07, 2012, 01:57:11 pmI know, I use them at home.I mistakenly forgot to include a clip I shot for that video explaining that:a) it's technically illegal for me to do sob) they often don't fit existing mounting holesc) many are designed to drive two tubes at once, so you can't just leave out one if you want.d) it's the same cost or even cheaper to simply buy the complete new luminaire with electronic ballast.Dave.

author: MartinX
author_rank: Regular Contributor
timestamp: July 07, 2012, 03:12:17 pm
content: Your old Thorn tubes had a colour rendering index of 80 and colour temperature was 4000K and 36W of course , that is what the 36W/840 marking means, so your camera measured it correctly.The starter is a bit more advanced, it is a gas discharge lamp with a defined ignition voltage. When power is turned on the lamp ignites and the heat generated makes a bimetallic strip in it close the contact shorting the starter causing current to flow in the filaments, since the gas discharge lamp is shorted it cools down and the bimetallic strip releases the contact and the high voltage pulse is created that (may) start the tube. If the tube starts then the voltage over the starter will be lower than the ignition voltage of the gas discharge lamp so then the starter does nothing waiting for the next starting event.The small initial current you see is the current through the gas discharge lamp. It is possible to take the casing of the starter and watch it in action as it is often in a clear glass bulb.

author: fchk
author_rank: Frequent Contributor
timestamp: July 07, 2012, 03:17:27 pm
content: The old tubes have an "840" marking on it. "40" mean 4000k, and the "8" is the color rendering index. The really cheap ones have a "5", "8" are the better ones, ond the really good ones in terms of color rendering have a "9". So your old tubes were not too bad at all, just a bit worn-out.

author: SeanB
author_rank: Super Contributor
timestamp: July 07, 2012, 03:30:19 pm
content: BTW those Thorn tubes are most likely from the early 1980's, the first generation of low power tubes. The original design calls for the full power tubes to be 40W, but in the first oil crisis and for residential use the power ratings were reduced to lower power but still compatible with the existing ballast equipment.With the current trace, the beginning section is the glow discharge in the starter, then the HF is the arcing as the contacts close. Then you have the filament heating, showing the core saturating. Then the start attempts, the tube not being able to conduct and thus restriking the arc in the starter until the tube finally strikes, where you will see the high amount of third harmonic distortion in the current waveform. In the starter trace you see the low current that ionises the gas fill in it and heats it uo, the uneven current is due to the different areas of each contact acting as a very poor rectifier. Then the preheat phase and finally only the high frequency current flow that is through the small capacitor in the starter.In the PFC capacitor there is a lot of distortion, it would look different if you placed the probe on the incoming mains waveform.BTW there should be a higher light output from the new tubes, you have gone from a 26W tube to one with 37W input power, so there you have 30% more power to be converted to light. Why do you not just use the 2 tubes the fitting is designed to use, you need a good light output so why not use the correct number of tubes per fitting. Using one and moaning about poor light is not good.The tubes all contain mercury, it works on a gas discharge in a low pressure neon/argon gas column to ionise the mercury to produce UV light which is converted to visible light in the phosphor. The NEC tubes are made in Japan, good tubes with hopefully a good life.BTW do not buy the LED retrofit tubes, you will find that they are absolute shite, with half the lumen output when new, and degrade badly in the first year. They are only good in cold stores where ordinary flourescent lamps perform poorly because they are too cold.

author: free_electron
author_rank: Super Contributor
timestamp: July 07, 2012, 04:05:48 pm
content: switch back to magnetic ballasts with an electronic starter...we threw all the electronic ballasts out of the lab.. a one inch piece of wire on the spectrum analyzer would pick them up ... very very annoying...

author: SeanB
author_rank: Super Contributor
timestamp: July 07, 2012, 04:19:43 pm
content: I recently bought a nice new set of Phillips energy savers, with a 4ft tube that runs at 23W and a 2ft tube running at 11W. Electronic ballasts matched to the tubes so that they will EOL properly and not flicker for ever. The 2ft tubes have already paid for themselves in energy saving on the lights that are on 24/7 in stairwells at home. 20 years ago I persuaded the BC to change the incandescent lamps to 18W fittings, took a year to get the payback in lamp cost alone over 60W incandescent lamps. Magnetic ballasts are much better life wise than any other method.

author: Monkeh
author_rank: Super Contributor
timestamp: July 07, 2012, 09:43:27 pm
content: Quote from: free_electron on July 07, 2012, 04:05:48 pmBest stop using those plastic fittings.But yes, there's not much need for HF fittings in an electronics lab. In a machine shop it's a different matter entirely.

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2012, 11:03:51 pm
content: Quote from: SeanB on July 07, 2012, 03:30:19 pmThe old tubes are 36W, not 26W.I am using two tubes now.QuoteYou can by good quality ones that work and last, but they are massively expensive.Dave.

author: RJSC
author_rank: Regular Contributor
timestamp: July 08, 2012, 12:12:32 am
content: Quote from: EEVblog on July 07, 2012, 02:43:27 pmOnly in Australia, for one not to be allowed to do anything on the electrical wiring. Give it a few more years and the next thing you know, you'll have to call a certified electrician to change you a light bulb!Do It Yourselfers there have to get organized and do some protest!Its not about safety, its just about ripping people off for work they can do themselves and keep a steady income to "certified electricians". If I went to Australia, I'd go to jail or I'd go nuts! I'm an home improvement enthusiast.When another Portuguese guy who went to Australia told me it's illegal to install a new lighting fixture yourself I was shocked!You can argue all you want about safety, but statistics say otherwise: check you neighbor New Zealand...Quotefrom:http://www.exploroz.com/Forum/Topic/59109/DIY-Electrical_Wiring_and_the_Nanny_State.aspxHail the Nanny State!Probably we should discuss this on a separate topic...What do you think, Dave?

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2012, 12:16:13 am
content: Quote from: RJSC on July 08, 2012, 12:12:32 amSilicon Chip tried, and failed.Dave.

author: zaoka
author_rank: Frequent Contributor
timestamp: July 08, 2012, 12:22:19 am
content: Hey Dave what kind of light bulb is the best to use for bench lamp?I would love to have a bulb that will equally provide light in like 20cm area only...Also is there any good brand for the bench lamp that will last long and be easy to use.. I always use cheap chinese ones and they always break in few months

author: RJSC
author_rank: Regular Contributor
timestamp: July 08, 2012, 12:28:44 am
content: Quote from: EEVblog on July 08, 2012, 12:16:13 amI guess Australian hackers/makers/"do it youselfers" are afraid of house wiring after all... They didn't joined the campaign!I've found and article from Silicon Chip which states:Quotehttp://siliconchip.com.au/cms/A_110652/article.htmlAnd what do you have to say about this one:QuoteIs this for real?!

author: David_AVD
author_rank: Super Contributor
timestamp: July 08, 2012, 12:32:04 am
content: Our benches at work use a single 36W tube mounted underneath the equipment shelf in such a way that the worker doesn't see the tube directly. The equipment shelf is approx 450mm deep and 600mm above the 900mm deep work surface.We also have a "troffer" fluoro (2x 36W tri-phosphor) in the ceiling above each worker. This gives a good light with no significant shadows. I also have one of those lit magnifiers but I've rarely used it.

author: IanB
author_rank: Super Contributor
timestamp: July 08, 2012, 02:32:43 am
content: Lighting requirements vary with the intended use of the space. For working with computers subdued lighting is much better than bright lighting (avoids glare). The lighting in your space may be perfectly fine for computer workstations, but not for your intended use as a workshop.My office has twin tubes, but I always keep them on the single tube setting. At home I have all my ambient lighting on dimmer switches at 30% or lower. But for reading or task lighting I have zoned lighting or spotlights as bright as necessary. The most important thing about lighting is not how bright it is, but that you can control the light level according to time and location and purpose. Light should be the servant of man, not vice versa!

author: jahonen
author_rank: Super Contributor
timestamp: July 08, 2012, 06:13:50 am
content: Out of interest, I checked what our Finnish Occupation Safety and Health Administration recommends for an illuminance for a precision work. They recommend at least 1000 lx for that. 200 is ok'ish for a normal office work.Regards,Janne

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2012, 07:41:16 am
content: Quote from: IanB on July 08, 2012, 02:32:43 amTry shooting a blog from every angle under the sun, the lighting needs are ridiculously complex. If you wanted to do lighting properly it'd take 10 minutes just to set up each new shot with multiple matched portable colour diffused light boxes all over the place etc.So it's simply not possible to get exactly right, you just have make do with what you've got, and what is the minimum hassle.Dave.

author: G7PSK
author_rank: Super Contributor
timestamp: July 08, 2012, 09:54:43 am
content: it is Getting much like Australia here in the UK (but without the sunshine) regarding electrical regulations, you can no longer put in extension wiring, wire or re-wire a house yourself without having it checked and certificated by a qualified electrician and sending the details and a copy of the certificate to the local council planners. You can replace a socket or bulb holder. But health and safety have gone further for commercial premises, I was amazed when I found my local bank closed early one day in order for scaffolding to be erected though out the building, this was so that the electricians could come in and change all the light bulbs, apparently as they are no longer allowed to work from ladders to change bulbs the bank sends a team around the country just changing bulbs whether they are blown or not due to the high cost of putting scaffold up for one bulb. When I wanted a spur socket I just put it in myself and if any one asked it has always been there, could not get away with that with a new build house as the plans for wiring will be lodged with the planners but as this house was last rewired in the 80,s who is to know, and I reckon that i can put in a socket and wiring as least as well as an electrician, mind you I have not had that special training that allows them to get all the sockets and switches at different heights and angles without any extra effort.

author: T4P
author_rank: Super Contributor
timestamp: July 08, 2012, 05:44:03 pm
content: Quote from: zaoka on July 08, 2012, 12:22:19 amI'm not who you are asking but heck ... I use a ikea tertial with a 22W panasonic CFL ... those go cheap

author: Crumble
author_rank: Regular Contributor
timestamp: July 09, 2012, 11:45:54 am
content: I do like you going for the quality stuff. Here in Holland I never saw the NEC types, even though I worked as a facility manager and had all kinds of the lying around. Out here Philips and Osram are the most common high-grade brands. The 5000K versions are uncommon in offices due to the very white light they give, making the office look "cold". Recent research showed it does increase productivity (can't find the reference right now), and Osram makes lamps with 8800K (!) colour temperature now.It does sound odd though it doesn't contain mercury, as far as I know the mercury content is essential for it's functioning. New ones only contain minimal amounts of mercury to minimise the use of this toxic material. One can sometimes see this with older fluorescent lights that are in continuous or semi-continuous use like street lighting and die due to other reasons than filament failure. The ingress of moisture from the air causes the lamp to emit less light with a pinkish colour.Didn't know they used up so much energy by the way, more than 50 Watts for a 37 Watts tube is nasty! I noticed the ballasts in a 58W lamp did get quite hot, but I figured it wouldn't be that much power loss (about 5 Watts or so). Theoretically a pure inductance wouldn't have any dissipation in it, so it should be possible to construct one without any losses at all.

author: SeanB
author_rank: Super Contributor
timestamp: July 09, 2012, 04:15:43 pm
content: The pink colour is from mercury starvation. The tubes are dosed so low with mercury ( 4mg or less per tube) that often the mercury is absorbed by the phosphor coating on the wall, and then the only light is from the neon/argon penning fill in the tube. You often see this in tubes exposed to cold temperatures, as the mercury condenses out on the walls, and the glow discharge is not enough to heat it to vapour again.

author: T4P
author_rank: Super Contributor
timestamp: July 09, 2012, 04:17:14 pm
content: Inductive losses ... they are bloody surprising!My 40W magnetic ballast drops about 7WI used phillips for a long time until i discovered they have a massive flaw in the lamps i bought ... they do not perform up to what the box claims not even by a far margin

author: David_AVD
author_rank: Super Contributor
timestamp: July 09, 2012, 11:33:31 pm
content: Just for fun, I just checked our workshop benches with a (cheap) light meter and got reading in the 1200 - 1500 Lux range at the working surface.The reading at my office desk (keyboard area) was 190 Lux with the blinds closed and 270 Lux with blinds partly opened (cloudy day).

author: EEMarc
author_rank: Regular Contributor
timestamp: July 10, 2012, 03:46:47 pm
content: That makes me wonder what the illumination of my lab bench is at. I've got 4 tubes about half the distance above the bench. I used to have eye strain issues when working on small stuff. Now I have much fewer issues. I'm still considering adding additional light.The following link has recommended light levels, higher light levels are recommended for more strenuous situations.http://www.engineeringtoolbox.com/light-level-rooms-d_708.htmlI'll have to measure my own lighting and compare.

author: Eliminateur
author_rank: Regular Contributor
timestamp: July 13, 2012, 07:31:27 pm
content: very interesting article and very interesting about those wanker laws...i mean, you live in a country/territory that practically has the most deadliest  per meter than anywhere else in the world (you have sharks offshore, giant spiders, tiny spiders that kill you on sight, poisonous lizard, all kinds of poisonous shrubberry, and a ton of other giant bugs and stuff that's deadly) yet god forbid you change a wire.....really bonkers...and this reminds me i bought a double-tube electronic ballast couple months ago that won't fit my fixture most likely and i'm too lazy to instal.....

author: ot1
author_rank: Contributor
timestamp: August 23, 2012, 05:42:49 am
content: In the USA, the homeowner can install or repair their own wiring or switches, fixtures, for major appliances etc, but most don't have the knowledge. Doing the work for someone else home isnt illegal but you should know what your doing of course. Depending on the scope of the job, a city or county permit may have to be pulled at a reasonable cost, then the work is inspected for code violations by an offical covered by the permit fee. New commercial electrical work, almost always, but not always requires a permit, depending on how extensive it is, a permit might be skipped . Commercial repairs do not, generally. Commercial work is always in metal conduit, residential mostly not, depending on the city or county but metal conduit really keeps the electrical house fires down, and most of this commercial work is done by a licensed electrician. But if you own your commercial property and know what your doing, you might skip the permit, but if another trade is working there to complete the buildout and they pull a permit, you could ge fined for not obtaining a permit.

author: T4P
author_rank: Super Contributor
timestamp: August 23, 2012, 06:36:14 am
content: I'll just say that where i live they ( the government ) don't care who does the wiring.Of course these advantages are quickly out-weighed by the disadvantages

author: ftransform
author_rank: Frequent Contributor
timestamp: August 23, 2012, 08:13:11 am
content: Lol what the fuck is with those laws. Is that shit actually enforced?\Do the electrical gestapo come around and check your wiring???Maybe the laws are so strict because Australia is a dry place hahahahhahahahahaor because everyone is perpetually wasted