22-12-2020, 10:00 PM
1
LED bulb conundrum.
I recently changed the bulbs in my living room chandelier from halogen to the equivalent LEDs. There are x9 G4 1.5W 12V. The transformer is inside the metal ceiling rose. They look great but there's one thing I don't understand. When I flick the light switch they don't come on, if I flick off then on again they come on, this happens every time.Any ideas?
22-12-2020, 10:10 PM
3
Re: LED bulb conundrum.
Originally Posted by Longdogs
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I recently changed the bulbs in my living room chandelier from halogen to the equivalent LEDs. There are x9 G4 1.5W 12V. The transformer is inside the metal ceiling rose. They look great but there's one thing I don't understand. When I flick the light switch they don't come on, if I flick off then on again they come on, this happens every time. Any ideas?
"Low-voltage halogen lamps are operated with voltage of 12V. This voltage is generated by a transformer from the mains. If there are problems after switching to 12V LED lamps it could depend on the used transformer.
Some transformers need a minimum load, which is not reached by the economical design of LED lights. In this case the connected lamps will flicker or stay off completely. Then only replacing the transformer with an appropriate LED power supply will help."
22-12-2020, 10:30 PM
5
Re: LED bulb conundrum.
All kinds of bulbs usually surge when you first turn them on.Halogen bulbs have no resistance when they are first turned on, hence the surge, the halogen filaments gain resistance as they heat up.
LED's always induce a constant load on the supply, so no surge, but the transformer may have circuitry to prevent the sudden surge of the halogen bulbs damaging the transformer, and so limits the initial start up ...If the startup is limited by a charging capacitor, once you have energised it with the first switch on, with the capacitor now charged, a second attempt will be successful. If the circuit is left for a few minutes the capacitor will have now discharged, and the double switching procedure must be followed again....hope this helps Longdogs....
Or what Judd said......
23-12-2020, 12:20 AM
6
Re: LED bulb conundrum.
Originally Posted by Judd
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What are they replacing?
Mmmm? Can't remeber now exactly, I threw the buggers out because they were burning a bit. They were definitely 10 watt and 12v
Originally Posted by Tedc
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Might be here LD,"Low-voltage halogen lamps are operated with voltage of 12V. This voltage is generated by a transformer from the mains. If there are problems after switching to 12V LED lamps it could depend on the used transformer.
Some transformers need a minimum load, which is not reached by the economical design of LED lights. In this case the connected lamps will flicker or stay off completely. Then only replacing the transformer with an appropriate LED power supply will help."
Originally Posted by Judd
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LED lamps normally require a constant current driver rather than a transformer. Your transformer will have a VA rating based on the number of lamps in the original fitting. How many lamps were there?
Originally Posted by OldGreyFox
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All kinds of bulbs usually surge when you first turn them on.Halogen bulbs have no resistance when they are first turned on, hence the surge, the halogen filaments gain resistance as they heat up.
LED's always induce a constant load on the supply, so no surge, but the transformer may have circuitry to prevent the sudden surge of the halogen bulbs damaging the transformer, and so limits the initial start up ...If the startup is limited by a charging capacitor, once you have energised it with the first switch on, with the capacitor now charged, a second attempt will be successful. If the circuit is left for a few minutes the capacitor will have now discharged, and the double switching procedure must be followed again....hope this helps Longdogs....
Or what Judd said......
That was my thoughts, that they almost needed to charge before they come on.Switching them on and off is not a problem so long as I know it is safe to leave them on. I have to say we rarely use the main light anyway.
23-12-2020, 02:15 PM
7
Re: LED bulb conundrum.
Originally Posted by Longdogs
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Mmmm? Can't remeber now exactly, I threw the buggers out because they were burning a bit. They were definitely 10 watt and 12vThats what is seems like Ted
Looking at it now and I think there are 9
That was my thoughts, that they almost needed to charge before they come on.Switching them on and off is not a problem so long as I know it is safe to leave them on. I have to say we rarely use the main light anyway.
23-12-2020, 08:53 PM
8
Re: LED bulb conundrum.
Originally Posted by Judd
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That means your transformer is possibly around 100VA (around 80 Watts allowing for losses). The 12V output may not be rectified into the 12V D.C. that your LED lamps require and so are reactive when the lights are first switched on (they resist the electricity trying to turn them on) but settle down as the reactance in the lamp reaches a certain value. As said before, 12V LED lamps need a driver board for them to operate efficiently.
Thanks Judd. So are they safe to use? As I said, turning them on twice is no bother.
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