Advice on flourecent tubes (or their equivalent)

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demag
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Re: Advice on flourecent tubes (or their equivalent)

Post by demag »

As an aside (another one!) Has anyone used led headlamp bulbs?

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white exec
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Re: Advice on flourecent tubes (or their equivalent)

Post by white exec »

I feel the need for a new (and probably heavyweight) thread here . . . :?

Hell Razor5543
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Re: Advice on flourecent tubes (or their equivalent)

Post by Hell Razor5543 »

To all that have contributed (now and any future additions), you have Ailsa's (and my) thanks. I believe that she is going for the 830 code tubes for now, but the idea of LED tubes does intrigue her.

elma
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Re: Advice on flourecent tubes (or their equivalent)

Post by elma »

dnsey wrote:
elma wrote:Depends on the tube and some are designed to use the original ballast but I've not ever seen one myself. Fitting the self ballasted LED with a fluorescent ballast would be a bad idea, kind of like fitting a domestic bulb to a streetlight ballast. Massively over voltage and something will probably fry.

Surely the PD across the LED cluster will simply be reduced by that across the ballast?
I'm assuming that 'removal' of the ballast involves shorting it out - if it were simply removed, there would be no supply for the LEDs.
Presumably the self-ballasted units simply have current-limiting resistors built in (or perhaps a more sophisticated regulator). 'Open' LED strips for mains use are readily available, using straightforward resistors plus a rectifier.
Streetlights, of course, use HV discharge lamps - a rather different matter, but as far as I can see, fitting an incandescent lamp would do nothing spectacular, as the lamp and ballast would similarly be in series.
The ballast is there in either case because once the discharge is established the lamp behaves as a virtual short circuit, so requires current limiting.
All the ones I have fitted were self ballasted. They required the old ballasts to be completely removed and the tubes to be wired directly to live and earth at the ballast end. At the other end the pins are left unwired, the first one I installed I accidentally bridged the pins on the non ballast end and this resulted in half brightness. The instructions warn that failure to remove the fleuroscent ballast will irreparably damage the tube, I haven't given any thought as to why I just accepted it would be over voltage. I'm not even sure if the leds are ac or dc and what voltage they use so have no idea what the internal ballast actually does.

dnsey
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Re: Advice on flourecent tubes (or their equivalent)

Post by dnsey »

That's what I was suggesting - that the LED tube should be connected directly to the supply. Removal of the ballast, with no other rewiring, would leave the LEDs with no supply. Shorting out the ballast (and unplugging the starter) would achieve what is required.
Just semantics, I suppose :wink:

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Re: Advice on flourecent tubes (or their equivalent)

Post by elma »

I get you now, was a little confused so went for the long explanation.