Author Topic: EEVblog #307 - Lab Lighting & Measurement  (Read 19316 times)

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Offline EEVblog

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EEVblog #307 - Lab Lighting & Measurement
« on: July 07, 2012, 09:08:19 pm »


Dave.
 

Online fmaimon

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #1 on: July 07, 2012, 11:57:11 pm »
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
 

Offline SeanB

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #2 on: July 08, 2012, 12:42:08 am »
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.
 

Offline EEVblog

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #3 on: July 08, 2012, 12:43:27 am »
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

I 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 so  ::)
b) they often don't fit existing mounting holes
c) 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.
 

Offline MartinX

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #4 on: July 08, 2012, 01:12:17 am »
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.
 

Offline fchk

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #5 on: July 08, 2012, 01:17:27 am »
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.
 

Offline SeanB

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #6 on: July 08, 2012, 01:30:19 am »
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.
 

Offline free_electron

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #7 on: July 08, 2012, 02:05:48 am »
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...
Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Offline SeanB

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #8 on: July 08, 2012, 02:19:43 am »
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.
 

Offline Monkeh

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #9 on: July 08, 2012, 07:43:27 am »
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...

Best 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.
 

Offline EEVblog

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #10 on: July 08, 2012, 09:03:51 am »
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 old tubes are 36W, not 26W.
I am using two tubes now.

Quote
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.

You can by good quality ones that work and last, but they are massively expensive.

Dave.
 

Offline RJSC

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #11 on: July 08, 2012, 10:12:32 am »
a) it's technically illegal for me to do so  ::)

Only 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...

Quote
First credit for source material in this note goes to Silicon chip magazine Issue june 2008.

Most of us on this site probably concur on the extent to which Australia has become a nanny state at the cost to ourselves both finnacially and from a saftey point of you.

Many of us get involved with electrical wiring from 12v to 240vac via vans trailers and the use of chargers, invertors and extension co-ords.

In Australia the nanny state has extended so far that one is not legally entitled to even pull a light switch from the wall (let alone disconnect the wires) to paint around it.

Yet our nearby neighbour N.Z. allows this and much more freedom in general wiring , replacement of sockets, construction of power leads and the repair of appliances than we do.

From the above lets first squash 2 immediate issues ->

1/ Standards - both countries use the same combined standard As/Nzs:3000

2/ Saftey - Deaths per million in Aust are approx 1 -> N.Z is a bit less at approx 0.7

Rather that beat up the dangers and hide information on how to safetly do some of your own work New Zealand publishes informative specific guides on how to do your own and what is permitted.


(How to do things - with diagrams)
http://www.energysafety.govt.nz/upload/33458/ecp51v18.pdf

(What you can do)
http://www.energysafety.govt.nz/upload/31994/brochure.pdf
 
from: http://www.exploroz.com/Forum/Topic/59109/DIY-Electrical_Wiring_and_the_Nanny_State.aspx


Hail the Nanny State!

Probably we should discuss this on a separate topic...
What do you think, Dave?
« Last Edit: July 08, 2012, 10:16:42 am by RJSC »
 

Offline EEVblog

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #12 on: July 08, 2012, 10:16:13 am »
Only 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!

Silicon Chip tried, and failed.

Dave.
 

Offline zaoka

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #13 on: July 08, 2012, 10:22:19 am »
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 :(
 

Offline RJSC

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #14 on: July 08, 2012, 10:28:44 am »
Only 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!

Silicon Chip tried, and failed.

Dave.

I guess Australian hackers/makers/"do it youselfers" are afraid of house wiring after all... They didn't joined the campaign!  :o
I've found and article from Silicon Chip which states:
Quote
Publisher's Letter

New Zealanders can legally do their own wiring – why can’t Australians?

Long-time readers of SILICON CHIP may remember that we conducted a campaign some years ago so that Australians could legally do their own house wiring. We pointed to New Zealand and many other countries where this was permitted and concluded that it was safer to make it legal and promulgate the necessary information on how to do it, rather than ban it and effectively dry up any information on how it can be done.

Partly as a result of readers’ apathy in not signing a petition we wanted to present to the various State governments, the campaign was completely unsuccessful. Nothing happened. It is still illegal for anyone other than a licensed electrician to do anything to house wiring. You cannot even legally remove a light switch from the wall in order to paint around it! Nor can you legally replace any faulty light switch, light dimmer, power point or even remove and replace a faulty light fitting, much less install a new one. At the rate we are going, it may eventually be illegal to replace a light bulb!

Don’t laugh. In our nanny state (all of Australia), people are prevented from doing anything mildly dangerous and changing a light bulb can be dangerous – you might fall off a chair or ladder, the light bulb may shatter in your hands or you might even get a shock if you attempt to change an Edison screw bulb if the light circuit is still powered on. On the other hand, it is demonstrably far more dangerous to walk down stairs – lots of people are injured this way. As far as we know though, there has not been any move to ban stairs.

Recently, we decided to take a different approach. Rather than rant on about how stupid the state governments are to ban domestic electrical work, we decided to point readers to websites in New Zealand where the information on such work is freely available. New Zealanders can do it you see, while we can’t. Australia and New Zealand use exactly the same wiring standard (AS:NZS3000), the same mains voltage and the same range of electrical fittings. So are Australians dumber than Kiwis? Clearly our state politicians and regulators must think so.

But we think we might have found out why the authorities might be even more concerned about the hazards than we thought. In one of the New Zealand brochures we feature in this issue (pages 14 & 15) there is even, perish the thought, a picture of a woman removing a light switch from a wall! Good grief! So even New Zealand women are smarter than typical Aussie blokes! Earth-shattering consequences.

Seriously, there is no good reason why Australians should not be able to do their own wiring and nor is there any reason why the information on how to do it should not be available from Australian authorities. Well, it doesn’t matter anyway because the New Zealanders, sensible people that they are, have made the information freely available to their citizens for more than a decade. And guess what: in that same period, the number of electrocutions per head of population in New Zealand has been less than in Australia. Clearly, doing your own electrical wiring need not be dangerous.

For anyone who has internet access, there is no longer any reason for anyone to remain ignorant about how to do their own wiring. The internet crosses all borders, so governments can do little to stop the flow of information.

So it is just silly that it is illegal to do home wiring in Australia. Large numbers of people do it anyway, as already recognised by state governments. Now that people can access the necessary info via the ’net, doing your own wiring can be quite safe, even though it might remain forever illegal in Australia. Or do we live in hope that common sense might ultimately prevail?
http://siliconchip.com.au/cms/A_110652/article.html

And what do you have to say about this one:
Quote
absolutely positively illegal unless you're a licenced electrician. my dad was an electrician his entire working life, but because he retired, and his licence expired, he can no longer do even the basics here now.

 ::) Is this for real?!  :o
« Last Edit: July 08, 2012, 11:09:41 am by RJSC »
 

Offline David_AVD

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #15 on: July 08, 2012, 10:32:04 am »
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.
 

Offline IanB

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #16 on: July 08, 2012, 12:32:43 pm »
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!
I'm not an EE--what am I doing here?
 

Offline jahonen

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #17 on: July 08, 2012, 04:13:50 pm »
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
 

Offline EEVblog

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #18 on: July 08, 2012, 05:41:16 pm »
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!

Try 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.
 

Offline G7PSK

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #19 on: July 08, 2012, 07:54:43 pm »
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.       
 

Offline T4P

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #20 on: July 09, 2012, 03:44:03 am »

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 :(

I'm not who you are asking but heck ... I use a ikea tertial with a 22W panasonic CFL ... those go cheap
 

Offline Crumble

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #21 on: July 09, 2012, 09:45:54 pm »
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.
 

Offline SeanB

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #22 on: July 10, 2012, 02:15:43 am »
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.
 

Offline T4P

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #23 on: July 10, 2012, 02:17:14 am »
Inductive losses ... they are bloody surprising!
My 40W magnetic ballast drops about 7W
I 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
 

Offline David_AVD

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Re: EEVblog #307 - Lab Lighting & Measurement
« Reply #24 on: July 10, 2012, 09:33:31 am »
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).
 


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