my new whats my transformer qiuz

[JohnW2]

Perhaps I should have rephrased that "I have no idea why the bulb (LED) worked all the way down to 5.2v despite the minimum voltage specified as 12v by Enlite. ... But technically it is not a problem to see why it actually works at minimum of 5.2v. ...

Even without re-phrasing, that was effectively what you wrote, and was the point I responded to. What you've said before (and in this message) is really about the (well, one possible) "technological how", leaving me uncertain as to the (non-technological) "why".

Given that they specify the minimum voltage as 12V, if it cost them more (in components and/or assembly costs) to have functionality down to 5.2V, it would not make sense for them to pay those additional costs. I therefore can but presume that, as I said before, this functionality must come 'unavoidably', at no additional cost, with the technology that they actually need.

Kind Regards, John

 

[Mikefromlondon]

yes I see your point John, and quite agree with that. "this functionality must come 'unavoidably', at no additional cost, with the technology that they actually need."

and yes I am surprised they have not made a claim that their LEDs can work from 6v dc to let us say maximum 16V dc, so a wide variation of input voltage will guarantee a steady light output, and when i evaluated their lamp, I found that if you take various current drawn v/s input voltage readings in steps of half volt, (ithink I put those readings on that other thread) then it is quite clear that at no time the maximum power exceeds 5 watts, may be just a fraction up or down, and so overall, their circuit is so well designed and therefore remains highly efficient at a wide supply range, at no time it exceeds maximum the 5 watt limit so no chance of a thermal runway, and self destruction under wide voltage variation, all the while the light remained steady.

But having said all this, it may hold truth for only bench test conditions using a 5 Amp 0-30V bench power supply, but of course those SMPS meant for Halogen lights were not suitable choice of power supply for these LEDs, as they have their own limitations, limitations in a sense that when the LED inverter circuit demands a surge of current, then the SMPS are not immediately able to meet that demand due to its own current limiting in action so this delay in supplying the current to the LED s causes them to flicker.


I think Enlite deserves a medal for their light technology. as it uses a truly a magnificent and highly efficient inverter circuit ( or if you like a built in driver ) hence the reason why they are not dimmable. I don't think you could dim them by either by using a pulse width method of supply.

One reason why it works on a power supply voltage as low as 5.2v, I am guessing that its comparator circuit uses a steady 5v supply internally regulated for reference to compare the output at 12.5V for the LED banks, and a comparator must have a good steady supply, and much lower supply level than it needs to control, otherwise it won't be able to compare if it self is jumping all over the place, it is a bit like one trying to read a graduated jar of water and trying to read how many cubic centimeters of water there may be in that jar when you are being driven in a car over a bumpy road, the water may be bouncing all over within the jar but also you can't keep your eyes steady at the scale.

So as long as there is a 5 or 5.2v at the input, the circuit starts to function and top up the voltage to necessary level to drive the banks of LEDs.

 

[JohnW2]

... and yes I am surprised they have not made a claim that their LEDs can work from 6v dc to let us say maximum 16V dc, ....

As you go on to imply, maybe you were just 'lucky' with your bench test, and perhaps these lamps do not, in general, operate reliably over anything like as wide a voltage range as you observed?

Kind Regards, John

 

[Mikefromlondon]

I see a lot of potential in them for use in Emergency Lighting since they can provide good constant intensity all the way down to 6 volts.
One can accommodate wiring using relays to automatically switch over to 12v battery bank in the event of mains failure. The battery could also be trickle charged by a cheap solar panel, cutting electricity costs further.

Hence it has advantages over those LEDs that are critical of input voltage and change in intensity.

 

[aveatry]

Wow you chaps do go on don't you
Here's one for you, in a room in my castle with dimable gu10 leds if someone takes a picture with an iphone the picture comes out with lines all the way over it, similar to this
View media item 96872Now the odd thing is that this picture below of me tranny in me loft was taken not under gu10 leds but with that same led torch as the photo above nd yet with no such lines apparent View media item 96940
Is what I am seeing with the lines in the photos the dimmer switch working with leds turning them on and off at different hz to get a dim effect to your eyes.

If the lights get dimmed would I then see wider dark lines as the dark phase was longer, might do some tests

 

[ericmark]

Interesting all my cameras have a focal plane shutter so one will not get that effect. I find the results from energy saving lights a problem as our eyes compensate for wrong colours but the camera does not do the job any where near as well.

I use a CD disk to test lamps so much easier than a prism alter the angle and you can see the colours used to get what to use looks like white light. The fluorescent lamp is quite poor compared with the LED and today the LED is used more and more for photographic lighting. Although the flash is good to work at high speed with a focal plane shutter it needs to flash many times as although my camera says it will work at 1/2000 of a second it still takes 1/180 of a second to expose the whole CMOS or CCD sensor so the flash which only lasts 1/20000 of a second must fire at least 12 times for the camera to get the whole picture. Or which is more common you have to limit the camera speed to 1/180 of a second.

The LED however has a huge advantage in that it can be switched on and stay on for at least 1/180 of a second so the camera shutter speed can be set to over the 1/180 of a second used with an Xenon flash gun. It also does not emit as much heat so will not effect the item being photographed.

Of course it is not a problem using 1/180 of a second in the dark, only in the light is it a problem.

 

[Mikefromlondon]

Quite interesting effects of LED lighting, which one couldn't have envisaged, it is not until one tries that one can see benefits and disadvantages of new things or technology. The old CRT TVs used to come up with pictures in cameras as dark lines travelling from top to bottom or either way, you also see something similar on modern LCD screens as well as the graphics are being switched on sequentially, pixel by pixel, with similar effect.

Those lines could also be dimmer doing its mark to space thing, or it could be the SMPS also, where it briefly goes off or under the minimum threshold of LEd's forward voltage requirement. An Led on a continuous power wouldn't generate those lines, so kind of strobe effect.

Have to remember LEDs are solid state devices and have no thermal inertia, as in incandescent bulbs, otherwise we would also see strobe effect on our old 100watt filament bulbs when the mains AC cycles through 0 points between positive & negative peaks.

I remember once I was arguing with a teacher in my physics class who said that mains 50Hz switches on and off 50 times per second, and I said no I don't agree with that since the mains switches on & off at double that or 100 times, as each peak has to go through a zero point (mid point) so in one cycle as the cycle begins, the light comes on say on a positive going peak, and half way through it would cross the mid point that is at 0 volts, so the light would go off, and then switch back on again as the cycle continues to peak towards the negative part and then come back to zero point and cycle ends, having thus switched off two times per cycle, the teacher was adamant that he was right and so was the rest of the sheep he was teaching. They all shouted at me to shut up and sit down. So I laughed and sat down, and though how disillusioned they were.

 

[aveatry]

Thought I would come back with a report on the g4 leds. The new ac-dc 12v LED transformer is now in place and all working fine. I would say that the LED g4s are not quite as bright as the halogen 20w but the fact that they are a white colour as opposed to the yellow halogens makes up for it.
GU10s I think have now come of age and are true replacements without being too big for the fitting which was the case not long ago, maybe in a couple of years the g4s and g9s will catch up with the GU10s

 

[winston1]

Thought I would come back with a report on the g4 leds. The new ac-dc 12v LED transformer is now in place and all working fine.

Good, but please read post 2 again. Noted that you thanked me last time.

 

[aveatry]

Thought I would come back with a report on the g4 leds. The new ac-dc 12v LED transformer is now in place and all working fine.

Good, but please read post 2 again. Noted that you thanked me last time.

This one ?

It is a switch mode power supply. It may or may not run LEds, you can but try.

Not sure what you are saying to me, if its did I try the transformer in the picture then no I didn't because the bulbs state DC12v on them and the transformer that I had was AC 12v

 

[slup]

He's being pedantic that you're still calling it a transformer and not SMPS...