Removing ballast circuit from fluorescent work light.

Thread Starter

Geeshik

Joined Dec 12, 2018
2
I have been through too many fluorescent bulbs in my Craftsman 19.2V (315.114073) flashlight. The most recent failure came in an attic when I was being attacked by hornets this summer, so I'm sure you can understand my frustration with it's fragility.

The light uses a 2G7 base fluorescent bulb. I had an idea to try and change it to an LED, and found a similar base LED that worked when I replaced it, however it flashed constantly before the bulb quit altogether. I am wondering how to remove (or even recognize) the ballast circuit in this light to get it to work.

The LED bulb is a 6W 85-265V bulb. As I said, it lit and seemed to be the correct brightness, but only flashed like a strobe light.
 

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DrewStupid

Joined Nov 28, 2018
64
I have been through too many fluorescent bulbs in my Craftsman 19.2V (315.114073) flashlight. The most recent failure came in an attic when I was being attacked by hornets this summer, so I'm sure you can understand my frustration with it's fragility.

The light uses a 2G7 base fluorescent bulb. I had an idea to try and change it to an LED, and found a similar base LED that worked when I replaced it, however it flashed constantly before the bulb quit altogether. I am wondering how to remove (or even recognize) the ballast circuit in this light to get it to work.

The LED bulb is a 6W 85-265V bulb. As I said, it lit and seemed to be the correct brightness, but only flashed like a strobe light.
Are you talking about a led tube or a bulb ?
 

Thread Starter

Geeshik

Joined Dec 12, 2018
2
Yes. Well, that it is both an led tube and a bulb. It is a bulb in that it has a 4 prong 2G7 base that plugs into a socket and it replaces a fluorescent u-tube/bulb.
 

BobTPH

Joined Jun 5, 2013
1,972
If it is designed as a direct replacement for a fluorescent bulb, it may very well require the ballast to work. Ballast, in this case, is actually an electronic circuit that boosts the battery voltage high enough for the fluorescent to work. The LED light would not work at the battery voltage.

Bob
 

Tonyr1084

Joined Sep 24, 2015
3,472
It flashes because a fluorescent tube requires voltage to ignite. The LED requires current. The ballast isn't designed to provide the necessary current. The PCB in the picture is the ballast and the component between the aluminum sheets is a transistor of some sort. Exactly what it is - is unidentified at present. It may be a FET. May be a MOSFET. Could be an IGBT or even just a BJT. Each works slightly different. Simply swapping the bulb may not do.

I have LED lighting in my laundry room. I replaced the fluorescent lamps with the recessed can type LED's. The wife complained about walking into a dark room, having to put the basket down and finding the light switch. So I replaced it with one of those motion detector switches. Upon restoring power the lights came on. After a few minutes they shut off. But instead of going off they just flickered at about 80% brightness. To solve that I added one more recessed light over the furnace. Instead of putting LED in it I put an old incandescent bulb. The load of the bulb makes the switch turn completely off and the lights don't flicker. By the way, the motion sensor switch was not designed to work with LED. As I said before, fluorescent works on voltage, LED works on current. That's also why standard dimmers can't dim LED's.
 
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DrewStupid

Joined Nov 28, 2018
64
If it is designed as a direct replacement for a fluorescent bulb, it may very well require the ballast to work. Ballast, in this case, is actually an electronic circuit that boosts the battery voltage high enough for the fluorescent to work. The LED light would not work at the battery voltage.

Bob
In RSA you rip eaverything out and just supply the driver end with 240 AC (Fused)
 

spinnaker

Joined Oct 29, 2009
7,815
I have been through too many fluorescent bulbs in my Craftsman 19.2V (315.114073) flashlight. The most recent failure came in an attic when I was being attacked by hornets this summer, so I'm sure you can understand my frustration with it's fragility.

The light uses a 2G7 base fluorescent bulb. I had an idea to try and change it to an LED, and found a similar base LED that worked when I replaced it, however it flashed constantly before the bulb quit altogether. I am wondering how to remove (or even recognize) the ballast circuit in this light to get it to work.

The LED bulb is a 6W 85-265V bulb. As I said, it lit and seemed to be the correct brightness, but only flashed like a strobe light.

What not just buy another work light? Something that actually works?
 

MisterBill2

Joined Jan 23, 2018
3,721
For TonyR, for most electronic controls for lights, you must use dimable lights. Putting a non-dimmable on a motion sensor destroyed the CFL with a flash and smoke.
 

Tonyr1084

Joined Sep 24, 2015
3,472
For TonyR, for most electronic controls for lights, you must use dimable lights. Putting a non-dimmable on a motion sensor destroyed the CFL with a flash and smoke.
I've been dimming "Non-Dimmable" (ND) LED's for years by keeping a single incandescent bulb in the same circuit. Same has been true when using motion detector switches, I have a few that have been in use for several years with no detrimental experiences to either the control source or the ND-LED's.

The incessant flashing that occurs when you don't have an incandescent load IS destructive to ND-LED's and ND-CFL's. But they work nicely when used with incandescent bulbs in the same circuit. Just now occurring to me is to test whether putting an incandescent in series with an ND-LED, whether the incandescent will glow at all, or whether the LEDs will light. Hadn't considered that before. May prove an interesting experiment. Maybe some day I'll even try it. But for now, ND-LED's switch and dim with no failure rates that I've seen so far. I HAVE seen standard LED's fail on standard wall switches. In fact, in the past 4 to 6 years I've had as many LED's fail that were not on dimmers or motion switches. As an observation, LED's seem to (as anecdotal evidence seems to say) last much longer when an incandescent is in circuit with the LED.

Eventually, through attrition I will have LED's that actually DO last 10 years as advertised. The principal failures of LED lamps has been due to electronics failure and NOT failure of the Light Emitting Diode elements within LED lights.

[edit] Oh, and I'm not a fan of CFL's. Hate how they have to warm up to give full brightness. In a cold garage they can take several minutes to produce useable light. Cold weather ignition is slow and difficult for CFL's. I suppose they make CFL's for cold areas, but I've never seen any so advertised.
 
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Tonyr1084

Joined Sep 24, 2015
3,472
In RSA you rip eaverything out and just supply the driver end with 240 AC (Fused)
You DO realize the Thread Starter (TS) is talking about a battery powered light? In fact, I have a few of them myself. I rarely use them. Most often the batteries are dead by the time I get around to using them. So "Dead" that the fluorescent tube barely lights at all. LED flash lights prove to be far more reliable - AND cheap. Retrofitting a fluorescent battery powered light with LED's, in my opinion, is wasted effort with diminished results. Just an opinion.

Some of those Super Bright LED's (SB-LED) can be blinding to gaze into, even for a tenth of a second. I've seen them in lots of auto parts stores, seen in tool rental places, even saw some recently at a model train festival in Milwaukee Wisconsin.
 

MisterBill2

Joined Jan 23, 2018
3,721
In response to post #1, I suggest removing ALL of the electronics not associated with charging the battery, if it is rechargeable. Then also remove the tube and it's connections. Locate a bunch of white high brightness LEDswith a reasonable current specification recommendation and mount them in the reflector, probably in strings of 5 or six in series. Next, with the number of LEDs selected so that the total rated forward drop is less than the battery voltage, select a small value resistor to drop the rest of the voltage at the rated current, or a bit less than the rated current. It will not be quite as efficient as one with an electronic switching regulator, but there will be less than one LED's worth of power wasted in the resistor, and the package will be quite reliable. Also a lot cheaper to create.
 

ebp

Joined Feb 8, 2018
2,332
There are ways to make fluorescent lamps light up from a DC source that are far from ideal and simply may not work with a LED lamp that is supposed to be able to replace the fluorescent.

The "best" circuits are careful to produce a symmetrical AC waveform for the lamp. This maximizes the longevity of the filaments and makes the current through the tube symmetrically AC - both filaments emit electrons equally. Other circuits will apply a waveform that has a large DC component, so that one end of the tube is always positive with respect to the other. The circuit is considerably simpler. It will get the tube lit up, but the lifetime is shortened because the filament at one end is always emitting the electrons for the arc. This "burns off" the emissive coating (which is what causes darkening of the ends of tubes and is a sign their days are numbered).

From the info I've been able to find, LED lamps that will work with electronic ballasts expect the type that produces "nice" AC.

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AC-mains LED light bulbs
I've used the one incandescent, one CFL or one LED lamp trick for years with my X-10 system which, like many things Tony mentioned, power the control circuit through the load. X-10 is a bigger problem because the "wall switch modules" also require the carrier current control signal to make its way through the load (lamp). I discovered about a year ago that the LED lamps make with what look like incandescent filaments will work in place of real incandescent lamps in parallel with a regular LED lamp. This means I can have the full benefit of the efficiency of LED lamps and have my X-10 stuff work OK. I do have a bit of an issue in a couple of locations because of weak signal (too many X caps in equipment eating the carrier current signal) where incandescent still works better than the "filament" LED lamps.

Like Tony, I never had any fondness for CFLs, but I quite like most of the LED lamps I've tried.
 
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