How to Power 2 Legged UV Lamp from Battery? - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 16, 2017, 02:41:12 am
content: i have several of this laying around for years...http://www.ebay.com/itm/4-x-9W-Nail-UV-Light-Bulb-Tube-Replacements-for-36w-UV-Curing-Lamp-Dryers-PR-/132186226090?hash=item1ec6e9bdaa:g:H6QAAOSw5cRZETQDhow to make circuit from battery power to operate this? i wish i have this unit to study how it works...https://www.lelong.com.my/handheld-blacklight-fake-bank-note-id-uv-light-money-detector-scanner-ebestseller-I5236238-2007-01-Sale-I.htmsearching in the net not giving me good luck... another think, some flou light are 4 legged, the unit above is 2 legged, so i'm a bit confused on what the difference. i can see both coils in this picture (for 4 legged and 2 legged) but i'm not sure where they are connected to. ohm test from pin to middle metal doesnt show any contiunity...4 pinshttp://www.ebay.com.my/itm/1-2pcs-4W-6W-8W-T5-UV-Ultraviolet-Tube-Germicidal-Bulb-Lamp-Light-Strip-Replace-/142363867030?var=&hash=item21258c3796:m:mZNyyf_ZvmscSp0llWdBx9w2 pinshttp://www.ebay.com.my/itm/Ultraviolet-9-W-for-Germ-Guardian-Sanitizer-EV9102-w-watt-uv-light-bulb-G23-2pin-/350568032321?hash=item519f7ba841:g:rWwAAOxy66pRwxyu

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 16, 2017, 06:04:11 am
content: I don't know for sure, but perhaps the two pin bulbs are to be used with an "instant start" ballast, which doesn't use the filaments for heating at all. Think of it like a xenon headlight: a high voltage initiates the arc and then a constant voltage or current sustains it. With them, the two sides of each filament are connected together.

author: james_s
author_rank: Super Contributor
timestamp: May 16, 2017, 06:13:06 am
content: Traditionally the 2 pin lamps have a glowbottle starter contained within the base, they are designed to run directly off line voltage with a simple choke ballast in series. It's entirely possible that some of the cheap ones are instant start though. There are a number of circuits out there for running fluorescent lamps off DC, most are simple self oscillating converters. You might also be able to use a CCFL inverter.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 16, 2017, 08:18:51 am
content: That makes a lot of sense. You wouldn't be able to pick up the starter with a multimeter.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 16, 2017, 12:03:16 pm
content: For best results you want to drive fluorescent bulbs with bipolar AC current, usually with a frequency of 20-40kHz; bipolar because that gives the longest lamp life and most even illumination (minimizes banding and darkening of one end); 20-40kHz because that is where the light output per input power peaks (about 10-15% more lumens per watt compared to 50/60Hz).In portable/battery power lamps the best circuit to use by far is a self-oscillating current-fed parallel-resonant push-pull (usually referred to as a resonant Royer or some variation thereof though, technically speaking, its not a Royer at all). Avoid the single transistor flyback circuits because those drive the lamp with a unipolar waveform and tend to be very inefficient (typically 50%).Bulbs with a two-pin G23 or GX23 base usually have a small capacitor inside that connects the two preheat filaments in series (see attached pic), the idea being that self-oscillating driver circuits tend to run at a much higher frequency before the lamp ignites, and so this capacitor will allow sufficient current to flow through the filaments until the lamp ignites. This usually works well enough, as long as the ambient temperature isn't too cold.

author: stj
author_rank: Super Contributor
timestamp: May 16, 2017, 01:43:47 pm
content: there are no shortage of schematics online for driving a 12" 8w tube from a 12v battery,but you need to break the base open to get to all 4 wires of the tube.to be honest, i would just go to junk sales looking for an old flourescent flashlight or car inspection light - a lot of those used an 8w tube.then you have the circuit ready made - because otherwise you will need to go through the headache of finding strange transformers or winding your own!!!!

author: Zero999
author_rank: Super Contributor
timestamp: May 16, 2017, 04:41:19 pm
content: Quote from: MagicSmoker on May 16, 2017, 12:03:16 pmNot quite. What you have there is a two pin lamp with a built-in glow starter. It isn't designed to be driven by a high frequency oscillator but at mains frequency, using an inductor or transformer with high leakage inductance to limit the current. The capacitor is just there for EMI suppression. It might work from a Royer oscillator or the suppression capacitor might be too big for it to work properly. Either way, you'll have more luck at lower frequencies.

author: SeanB
author_rank: Super Contributor
timestamp: May 16, 2017, 04:52:28 pm
content: PL lamps do work with electronic ballasts, they glow for a second or two then start up. however the simplest is just to use a 9W choke ballast in series with the power line, and put in a PL socket for the lamp. Ballast only has 2 wires for 220VAC use, and works well. If you want to light 2 simply use a 13W ballast in series, and put the 2 tubes in series as well, they will run, as the glowbottle starter in there will break down at around 90VDC across it, and the 2 in series will start with 220VAC applied.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 16, 2017, 05:05:43 pm
content: Quote from: Hero999 on May 16, 2017, 04:41:19 pmHmm... my understanding is that the capacitor is to allow starting with high frequency electronic ballasts while the glow starter is for mains frequency ballasts. But, I could very well be wrong.

author: stj
author_rank: Super Contributor
timestamp: May 16, 2017, 05:45:09 pm
content: Quote from: SeanB on May 16, 2017, 04:52:28 pmread the thread from the top, the guy wants to use a battery!

author: stj
author_rank: Super Contributor
timestamp: May 16, 2017, 05:46:37 pm
content: Quote from: MagicSmoker on May 16, 2017, 05:05:43 pmthe capacitor is to reduce switching RFI so you dont take out everybody's tv & radio.

author: Gyro
author_rank: Super Contributor
timestamp: May 16, 2017, 06:26:25 pm
content: Yes, that capacitor has been in glow starters (the can type) since year dot, long before the advent of electronic balasts. An interesting concept though, with the right value of capacitor (bigger) it mightjustbe possible to support both, as long as the glow tube didn't get in the way.

author: james_s
author_rank: Super Contributor
timestamp: May 16, 2017, 09:13:43 pm
content: An electronic ballast may work anyway, if it doesn't work directly then you could just a drill to carefully go in and break the glowbottle so it doesn't shunt the voltage. The are lots of inexpensive camping lanterns and such that use CFLs similar to that, I see them in thrift stores frequently. The circuit from one of those may work if you don't want to brew your own.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 17, 2017, 12:41:30 am
content: Quote from: stj on May 16, 2017, 05:45:09 pmbecause i thought battery operated circuit should be much simpler and i thought this ccfl bulb will work on low voltage (12V maybe?) at its both pins during normal operation. but it seems to jump start this bulb still needs somesort of high voltage oscillator. my brain hurts listening to those advice esp when a schematics drawing is missing. i dont even know how a "ballast" worki thought i will be getting one of thishttp://www.ebay.com.my/itm/36W-Acrylic-Nail-Art-UV-Lamp-Curing-Light-Gel-Polish-Dryer-With-Timer-4-Bulbs-/142174713183?var=&hash=item211a45f55f:m:mxLXfaFws7IjDA8sY577vLQand starts from there... the money spent on readymade should be a lot more economical to cover the time i'm going to waste tinkering the unknown, and probably the cost of burning parts too. anyway, this is for my pcb photo resist / mask curing project using the uv bulb.

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2017, 01:28:42 am
content: As I recall the voltage across these lamps is something around 40-50V in operation with a significantly higher spike required to start the lamp. A ballast is a simple enough concept, in its most basic form a resistor will work to limit the current just as is done with an LED. In practice an inductor is normally used, the reactance limits the current and it doubles as a convenient way to produce a high voltage spike to start the lamp.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 17, 2017, 12:23:05 pm
content: Quote from: Mechatrommer on May 17, 2017, 12:41:30 amAh, okay, let's back up a second. I thought you wanted to make a battery powered lamp as well. If you can operate the bulb from the mains then things can be greatly simplified, especially for a lamp that won't be operated very much.A ballast in electronics is merely a means of limiting current - it could be a resistor, an inductor or even a capacitor.In all cases you need to know, at a minimum, the voltage drop across the bulb during operation and the recommended current. The PL-9W (aka CFT-9W/G23) bulb I cracked open - which, coincidentally, is the same size/wattage as the 4 bulbs used in that UV nail drier - requires 59V volts at 0.18A. Starting the bulb requires a much higher voltage, however - 3x to 6x is typical - and this voltage varies inversely with temperature (hence the use of preheat filaments). You can skip preheating - at the cost of bulb life - by applying a much higher voltage during starting (up to 10x); this is what "instant start" lamp fixtures do.There are MANY ways to operate fluorescent bulbs, and that may be a source of confusion here. If the peak of the mains voltage is sufficiently high to reliably start a bulb then either a resistor or capacitor can be used as the ballast, with the capacitor greatly preferred for efficiency reasons. In this case, 220V RMS mains should be more than sufficient to reliably start a PL-9W bulb, while starting from the 120V mains in the US would be marginal without some assistance from inductive kickback (hence the popularity of the choke/inductor type ballast in the US).A passive ballast (whether a resistor, capacitor or inductor) needs to drop the difference between the RMS mains voltage and the bulb voltage at the desired operating current. More specifically, driving a bulb rated for 59V at 0.18A from 220V/50Hz mains requires a ballast resistance (or impedance, to be more correct) of 894 ohms. That can be achieved with a resistor, of course (but watch out for the nearly 30W in loss!), or a 3.56uF capacitor or a 2.846H inductor.If going the capacitor route then you need to use an appropriate type for direct mains operation. Examples would be any X2 or Y2 rated capacitor (though you'll require a whole bunch of them to get to 3.56uF), metallized or foil plastic film capacitors (e.g. - MKP, MKT, FKP, FKT, etc.) of sufficient voltage rating (usually a DC rating >430VDC will be required), oil filled "motor run" and other various but less common types.Otherwise it should be possible to buy the appropriate inductor (aka "magnetic") ballast from a hardware or electrical supply store. You'll also need a socket for the bulb. Usually 9W twin tube bulbs are coded as "G23" base, but could also be GX23. These two bases might look the same, but they are not interchangeable.