12V transformer and LED bulb 12V (information Velleman)

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Christophe
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Re: Small feedback




by Christophe » 03/08/13, 14:30

skabill2000 wrote:By cons I am considering replacing the transformer because I have the impression that the same configuration if it seems stable for now, could damage the LED bulbs.


Risk ... to put it mildly!

The change of transformer, it's a bit what we advise you from the beginning it seems to me ...

: Arrow: https://www.econologie.com/shop/alimenta ... p-429.html : Arrowl:
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by Did67 » 03/08/13, 14:39

For a boeotian like me, can someone explain to me why and how there are 12 V AC LEDs

[for the 220 V AC, I imagine that everything is in the ballats, and that if it is a serious manufacturer, it is studied for - I have two or three Xanlites of this type: great and it lasts ... I had 10 220 V AC "chinoiseries" on exterior posts: in less than a year, 9 out of 10 burnt: one of the ballast parts systematically burnt; it was visible]

So an LED works, in the end, in direct current. No ?

If I understood correctly, transformers like those put online above reduce the voltage, but keep the alternating current, which does not bother a halogen (the Joule effect does not care which direction the current goes; it is just sensitive to "rms current").

Hence, in general, without precaution, the disappointments when we are content to connect an LED bulb instead of a halogen. The connections being the same, it's tempting! What in good boeotien I did before thinking a little and putting adequate transformers.

I had a lot of posts, with two kinds of transformers, roughly: a) "big heavy thick", which I suppose to be "windings"; b) ultra-thin I suppose electronic ... I think neither of the two is suitable. The 1st convert well into 12 V but alternating; the second transform, straighten, distort, I suppose ...

So if for a Boeotian knowing what is a current, a voltage, alternating, sinusoidal but little more, a "summary", or a sort of table, would be welcome.
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chatelot16
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by chatelot16 » 03/08/13, 14:42

especially that for 15 euro it's not worth hesitating! the slightest blown LED due to poor power supply will cost more!

I sometimes use this kind of industrial food
gotronic.fr/art-alimentation-rs25-12-20103.htm
but it's good to put in a well-protected electrical cabinet, because this all-perforated box is good for collecting dust until the electronics break down

the 15 euro power supply from the shop is cheaper and better because it is tight!
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by chatelot16 » 03/08/13, 15:03

Did67 wrote:For a boeotian like me, can someone explain to me why and how there are 12 V AC LEDs


the led only is an electronic component which must be supplied at constant current, and not at constant voltage

a model of led which must function at 700ma maximum will make the tension which it wants according to the temperature, for example 2,85V

if we try to supply it with a voltage source set to 2,85V, just put 0,05v less so that the led goes out completely or 0,05V more so that the current increases and exceeds the maximum tolerable

there is therefore in the led bulb an electronic current regulator circuit

and to avoid having to spot the + and the minus the lamp generally contains a diode bridge which allows to connect in 2 directions, so also in alternative

and if the electronic regulator in the led lamp is effective over a fairly wide input voltage range the led lamp can be connected to alternating 12V more or less well regulated as we give to halogen

but I have never yet disassembled a 12V led lamp to know exactly what is in it

I just dismantled a 220V led lamp where there was a capacitor current limiter which I find very bad
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by chatelot16 » 03/08/13, 16:01

looking in the shop if a tolerance was specified on the supply voltage of 12V leds I see this

https://www.econologie.com/shop/ampoule- ... p-393.html
Bulb MR16 12V with 3 Leds 5W for low voltage 12V AC / DC luminaires
Features
MR16 bulb with 3 LEDs
Almost does not heat (safety for children for example)
Light power equivalent to a 40W halogen bulb for 5W consumed
MR16 base, voltage 230-240V AC


there is an error to correct with this 230 240!
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by Did67 » 03/08/13, 16:45

Thank you. I already understand a little better! I did not know at all that it was the current which is constant!

I saw on a site with LEDs for motorhomes, very wide tolerances; like 10-17 V!

I imagine that it is linked to variations in battery voltage.
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by chatelot16 » 03/08/13, 17:28

Did67 wrote:I saw on a site with LEDs for motorhomes, very wide tolerances; like 10-17 V!


exactly! a led lamp that requires precise 12V will quickly burn out on a vehicle that drives and charges the battery at 14,5V

and even worse with a charger on 220V it often goes up to 15V

announcing a tolerance of 10 to 17 is a sign of quality: this kind of lamp should easily withstand being mounted on a halogen transformer
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by Did67 » 04/08/13, 09:53

Going to check if my memory was not playing a trick on me, I realize that there are even more tolerances: 8 - 30 V

ampoule-leds.fr/ampoules-led-camping-car-c-1_167.html

But beware, it's DC, so beware of ballasts coming out of 12 V AC (see photos posted online above). There, there would be, in my opinion, like a schmilblic if we replace the halogens (which have no problem with 12 V AC) by these bulbs for campingt-car! [Or am I wrong?]
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skabill2000
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CC or AC ?? that is the question




by skabill2000 » 04/08/13, 12:12

Christophe wrote:
skabill2000 wrote:By cons I am considering replacing the transformer because I have the impression that the same configuration if it seems stable for now, could damage the LED bulbs.


Risk ... to put it mildly!

The change of transformer, it's a bit what we advise you from the beginning it seems to me ...

: Arrow: https://www.econologie.com/shop/alimenta ... p-429.html : Arrowl:


Yes that's for sure I was well aware of the risks involved 8)
...

- however, as my bulbs are given to be 12V in AC and that the transformer you propose is him in CC, can the set work?

- If the answer is yes "we can very well mix DC transformer and AC bulbs", is there no problem to put 8 LED bulbs on the same line? there is no history of interference created by bulbs which, by accumulating, cause flickering or stop of the bulbs ?

Thank you.
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skabill2000
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Re: CC or AC ?? that is the question




by skabill2000 » 06/08/13, 17:57

skabill2000 wrote:- however, as my bulbs are given to be 12V in AC and that the transformer you propose is him in CC, can the set work?


The answer is yes : my 8 LED AC bulbs remain stable with an AC / DC transformer beast in the 12V position.

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