Fluorescent ballasts - Page 1
Forum section: electronics / general

author: steve30
author_rank: Frequent Contributor
timestamp: October 13, 2012, 01:01:41 pm
content: I'm playing with fluorescent lighting for my combined bedroom/lab and would like to try dimmable fluorescent tubes.I've been looking at Philips electronic dimmable ballasts, but I was wondering if anyone here had any recommendations or suggestions for manufacturers of ballasts, as dimmable ones are quite expensive.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 13, 2012, 01:32:08 pm
content: Look around for broken LCD monitors and TVs. (In particular, look for ones where the LCD panel itself is damaged, but the backlight works.) Then remove the main board and LCD (jump some pins on the power supply board to turn it on and connect a 555 circuit to provide the PWM) and you have a dimmable fluorescent lamp!Or if you want to build your own, Linear has some good app notes on how to do it.Of course, everyone's going towards LEDs nowadays. If you can wait until after Christmas, you might be able to pick up a lot of white LED lights for cheap. (Strip them down and rebuild them with a better driver.) Don't expect very good LEDs, but they should still last a long time if you derate them.

author: steve30
author_rank: Frequent Contributor
timestamp: October 13, 2012, 01:39:44 pm
content: Hmm, not really thought of DIY, but its something I certainly wouldn't mind having a go at.But maybe for DIY I would stick to small tubes, as I am planning on using 58W 5ft tubes for the room lighting.I've considered doing something with LEDs, but I figured that would be too expensive and too much hassle, at least for now. I'm coming from incandescent so the energy saving from fluorescent will already be good, and the long, cylindrical, and diffused nature of fluorescent tubes makes them ideal for what I want.

author: SeanB
author_rank: Super Contributor
timestamp: October 13, 2012, 01:45:18 pm
content: Expensive, and really no other alternative unless you look at making up an old dimmable magnetic ballast or find one on eBay.

author: steve30
author_rank: Frequent Contributor
timestamp: October 13, 2012, 02:35:24 pm
content: Quote from: SeanB on October 13, 2012, 01:45:18 pmHow would you make a magnetic ballast dimmable?

author: SeanB
author_rank: Super Contributor
timestamp: October 13, 2012, 02:43:04 pm
content: You use a transformer to supply 4VAC to the heaters on each end which then enables you to use an inline hard fired dimmer to control the current in the magnetic ballast.

author: Flávio V
author_rank: Regular Contributor
timestamp: October 13, 2012, 10:31:46 pm
content: Cheap good LEDs:http://www.digikey.com/product-detail/en/BXRA-C0361-00E00/976-1019-ND/2331647You can't say than those are expencive....2.8€...

author: steve30
author_rank: Frequent Contributor
timestamp: October 14, 2012, 01:51:13 pm
content: Good LEDs are reasonably priced, but it isn't practical for me at the moment. I would need lots of them, then I'd have to deal with PCBs, heatsinks, diffusers, drivers etc. And it would probably still cost more than fluorescent. Certainly something to play with, but not yet.I managed to get a dimmable ballast cheap on ebay so I'll see how that goes.

author: akcoder
author_rank: Contributor
timestamp: October 15, 2012, 06:17:40 am
content: Quote from: steve30 on October 14, 2012, 01:51:13 pmYou didn't say what you intend to ultimately do with this, or where you intend to use your dimable ballast, but if you need good, cheap lighting check eBay. I picked up a 10 meter strip of white LEDs for $14 shipped.eBay auction: #120916631286They take 12v in, have an adhesive back and can be cut every 3 LEDs. I have 15 meters underneath my workbench and it they work great!-dan

author: steve30
author_rank: Frequent Contributor
timestamp: October 15, 2012, 08:51:12 pm
content: Quote from: akcoder on October 15, 2012, 06:17:40 amI'm going to have two or three 5ft tubes lighting up the general area of my combined bedroom/lab, and then another 5ft tube to illuminate my bench.LEDs would actually be feasable for the bench lighting, but if I'm having tubes elsewhere in the room, I may as well have the desk match. That way, the desk light will be the same colour as the rest of the room.Currently by room lighting and bench lighting are different colour temperatures and different CRIs and it looks kinda strange.

author: HardBoot
author_rank: Regular Contributor
timestamp: October 16, 2012, 03:57:23 am
content: Xenon is efficient and very easy to dim, but dimmable power supplies are rare.Halogen is cheaper, easier, and less efficient.I don't like LED dimming, but if you have several led strips and a diffuser you can turn on/off however many you want.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 16, 2012, 04:33:33 am
content: Quote from: HardBoot on October 16, 2012, 03:57:23 amI haven't heard about Xenon lights apart from flashbulbs, fancy car headlights, and projector lamps. Their high cost would make them impractical for everyday room lighting. Even the car headlights are being replaced by LEDs.LEDs are actually the easiest to dim. Just reduce the current and/or PWM the supply.

author: Lawsen
author_rank: Frequent Contributor
timestamp: October 16, 2012, 06:49:10 pm
content: Magnetic fluorescent lamp ballasts are ban by the government in the U.S.A. 40 Watts or greater are no longer available as new stock in stores in the U.S.A. The large tubes are not dim able. Some compact fluorescent lamp bulb that fits into an Edison T22 socket are dim able, but the box has to label dim able. You will need a special dimmer for it. A regular dimmer for incandescent light bulbs will not work too well, because the lower limit will not be dim able, while the upper limit to half are dim able. Here is a good company that has quality dimers by Lutron:http://www.lutron.com/Products/StandAloneControls/Dimmers-Switches/Pages/DimmersSwitches.aspxYou can make your own dimmer with the 555. Old East German Aus Jena Laboval 4 microscope (now, Zeiss, after reunification, the Berlin Wall crumbled.) has a 555 based incandescent light bulb dimmer, but it does not works too well for the lower limit.https://www.google.com/search?q=555+led+dimmer+circuit&hl=en&client=firefox-a&hs=2ks&rls=org.mozilla:en-US:official&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=K6t9ULy7EorO2AXJ0ICAAg&ved=0CCAQsAQ&biw=1268&bih=647

author: Zero999
author_rank: Super Contributor
timestamp: October 17, 2012, 12:13:27 am
content: It's possible to dim a fluorescent with a magnetic ballast by adding a phase controller and a small incandescent lamp.I haven't tried it myself but someone on another forum did and it apparently works.

author: Lawsen
author_rank: Frequent Contributor
timestamp: October 17, 2012, 05:36:41 am
content: It will work, where the phase controller is a high current rheostat and the 15 Watt light bulb is like a resistance load to allow dimming at a lower limit. This is not an electricity efficient circuit. 40 Watts FT40 fluorescent lamp tube are not meant for this. It seems to work. It is still neat to be able to dim a large fluorescent tube with a non dim able magnetic ballast.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 17, 2012, 01:33:06 pm
content: Maybe try a ceiling fan speed control? It would be designed to operate properly with an inductive load.For a new design, I would suggest using LEDs they are very easy to dim. Linear has a bunch of app notes on dimming fluorescents and it's it's not that easy, especially if you want to dim very low. In contrast, LEDs can be easily dimmed by merely lowing the current and/or PWMing the drive.

author: steve30
author_rank: Frequent Contributor
timestamp: October 18, 2012, 01:06:08 pm
content: My Philips HFR 258 TLD EII arrived yesterday,Got it all hooked up with a couple of tubes and it works nicely.I really should get a power meter so I can do some comparisons in power consumptions between the various kinds of lighting I have here.