cfl bulb details - Page 1
Forum section: electronics / beginners

author: Halford
author_rank: Contributor
timestamp: February 22, 2015, 04:09:41 pm
content: Hi everyone,I wan following an interesting tutorial on how to make a Lamp Jar with a CFL bulb and a battery, but I got lost when he used parts from an old disposable camera between the tubes and the battery (tutorial here:http://www.instructables.com/id/Jar-Lantern/)I tried to find online how the cfl bulb works.. I see the entry and I understand it rectify the current... but the I do not understand how it supply the tubes... what voltage... I'm pretty lostI found many pictures of the first part of the bulb, but I did not find what voltage can run on the bulb wire itself and what do they need if I want to use it with a battery..do you have any papers on it? thanks for any tip or directionsHal.

author: Kjelt
author_rank: Super Contributor
timestamp: February 22, 2015, 04:25:47 pm
content: Read wikipedia first for a 101 on cfl esp. Tubelight which is the same principle.Then the article you read IMO: garbish. It is a wonder it worked at all, using a flash circuit of a cameraTo electronically drive a cfl needs a high voltage circuit for ignition, then carefull current control of the filament currents and the lampcurrent.If you are a beginner be very carefull these things have high voltage ignition, i would suggest if you like to build such a lamp to start with leds in a plastick tube

author: Simon
author_rank: Unknown
timestamp: February 22, 2015, 04:49:05 pm
content: sounds like a pointless project and yes beware of dangerous voltages, even if it on;y runs off a battery a capacitor charged to a high voltage can be lethal.

author: Zero999
author_rank: Super Contributor
timestamp: February 22, 2015, 04:54:16 pm
content: The flash unit of a camera will work but it'll be rubbish.The most common way to do this is to use a circuit called the Royer converter.http://www.diodes.com/_files/products_appnote_pdfs/zetex/an14.pdfhttp://ludens.cl/Electron/Fluolamp/fluolamp.htmlIt's not that dangerous, since it uses high frequency AC which is unlikely to cause a lethal shock but it will burn you so be careful. Observe the usual precautions when working with high voltages.What about using LEDs? They don't need high voltages and are now more efficient than CFLs, if driven correctly using a switched mode converter, rather than a wasteful resistor.

author: Halford
author_rank: Contributor
timestamp: February 22, 2015, 05:31:31 pm
content: Thanks for all replies!I'm used to LEDs, ans I found this tutorial nice as I had a bulb sitting around and it looked nice in the jar.... that's the real reason, and because I like to learn new things in general

author: miguelvp
author_rank: Super Contributor
timestamp: February 22, 2015, 08:19:29 pm
content: A cold cathode light inverter as used for lighting your PC will light up those CFLshttp://www.newegg.com/Product/Product.aspx?Item=N82E16811994005That's what I used for this:Edit: but be carefull:Output voltage of inverter: 680vOn the 9 Volt battery I measured over 600VAC at startup and settling at 518VAC, frequency I was getting was about 35KHz.

author: void_error
author_rank: Frequent Contributor
timestamp: February 23, 2015, 12:03:49 am
content: Quote from: Hero999 on February 22, 2015, 04:54:16 pmYou beat me to it.I've played with those circuits a couple of years back. The 'high voltage' transformers can be salvaged from old/dead LCD monitors which use a CFL backlight, they're usually made for 12V operation, although some newer ones use more advanced circuitry with only one primary winding on the transformers which means you can't use them to make a Royer converter.

author: Kjelt
author_rank: Super Contributor
timestamp: February 23, 2015, 06:53:03 pm
content: Just so you have something to compare, this is how a professional high frequency dimmable cfl driver looks like.Not something you design yourself easily