Electronics > Beginners
Turning a florescent replacement type A LED T8 into a type B
amyk:
--- Quote from: dclevy1 on July 16, 2018, 05:42:01 am ---Okay type A are LED T8 bulbs that require a ballast to operate because they are supposed to be easy to retrofit into pre-existing fluorescent light fixtures. Type B bulbs are LED T8 bulbs that can be wired directly to 120v ac Mains voltage and you are able to bypass a ballast completely so you can use it as typical lighting.
--- End quote ---
That makes it much clearer, thanks. In other words, type A are the ones which don't have a current limiter and rely on the ballast for current limiting, while type B does. Depending on the rated current and voltage, a capacitor or resistive dropper would probably be suitable, but once again you need to post that information.
--- Quote ---If you are willing to help me do you need the item number or model number on the components themselves?
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The marking on the component itself. A clear high-resolution picture would be preferable.
Kjelt:
--- Quote from: amyk on July 17, 2018, 01:22:55 am ---That makes it much clearer, thanks. In other words, type A are the ones which don't have a current limiter and rely on the ballast for current limiting, while type B does. Depending on the rated current and voltage, a capacitor or resistive dropper would probably be suitable, but once again you need to post that information.
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The cupper/iron ballast is nothing more than a coil. You don't know what the coil does in serial with the tube.
It could for instance drop the voltage with 20V or so, in that case they would have fitted less leds in the serial led string.
That is why I say, buy one type B and compare it:
- pcb equal ?
- components missing , different or additional components ?
- are the amount of leds equal ?
- is the Vf of the leds equal ?
that kind of things. Ofcourse you can just put it on a DC supply with current regulation and see with what voltage/current it reaches its nominal power.
edavid:
--- Quote from: amyk on July 17, 2018, 01:22:55 am ---Depending on the rated current and voltage, a capacitor or resistive dropper would probably be suitable, but once again you need to post that information.
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No, a capacitive or resistive dropper is not suitable. These are 32T8 replacement lamps, so they are probably rated about 18W. They need a proper power supply (SMPS with constant current output).
--- Quote from: Kjelt on July 17, 2018, 06:53:09 am ---The cupper/iron ballast is nothing more than a coil. You don't know what the coil does in serial with the tube.
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The "Type A" LEDs only work with electronic ballasts, not magnetic ballasts.
amyk:
--- Quote from: edavid on July 17, 2018, 02:32:33 pm ---
--- Quote from: amyk on July 17, 2018, 01:22:55 am ---Depending on the rated current and voltage, a capacitor or resistive dropper would probably be suitable, but once again you need to post that information.
--- End quote ---
No, a capacitive or resistive dropper is not suitable. These are 32T8 replacement lamps, so they are probably rated about 18W. They need a proper power supply (SMPS with constant current output).
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18W @ 120V is 150mA, which is at the high end but still within the usual currents that capacitive droppers are used for.
(I'm more used to 240V circuits where the current is halved, <100mA is definitely possible with a cap dropper.)
james_s:
--- Quote from: Kjelt on July 17, 2018, 06:53:09 am ---
--- Quote from: amyk on July 17, 2018, 01:22:55 am ---That makes it much clearer, thanks. In other words, type A are the ones which don't have a current limiter and rely on the ballast for current limiting, while type B does. Depending on the rated current and voltage, a capacitor or resistive dropper would probably be suitable, but once again you need to post that information.
--- End quote ---
The cupper/iron ballast is nothing more than a coil. You don't know what the coil does in serial with the tube.
It could for instance drop the voltage with 20V or so, in that case they would have fitted less leds in the serial led string.
That is why I say, buy one type B and compare it:
- pcb equal ?
- components missing , different or additional components ?
- are the amount of leds equal ?
- is the Vf of the leds equal ?
that kind of things. Ofcourse you can just put it on a DC supply with current regulation and see with what voltage/current it reaches its nominal power.
--- End quote ---
T8 tubes longer than 18" in the US use electronic ballasts. The larger diameter T12 tubes above that length used autotransformer ballasts. The choke ballasts that are still very common in many parts of the world need more than 120V for longer tubes.
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