my new whats my transformer qiuz

[winston1]

Ironically he sold him Powertran brand SMPS, which clearly says they are meant for halogen 12v lights!!!

So, at this stage, he should have taken them back as not fit for purpose sold for. Did he?

 

[bernardgreen]

It is a bit annoying / ironic as I have spent many hours this week creating a design for pulse width modulated supply for LED lamps to make them intentionally flicker like a real candle flame in a lantern. Waxing and waning like a candle in the breeze and not just blinking on and off. Electronics simple, but designing the "random" flicker pattern was the hardest part. ( pseudo random, it repeats after about 15 hours ).

 

[aveatry]

Well my new g4s are here and the box and written on the lamps it says DC 12v so now I need to swap the transformer I have which is a AC 12v to a proper dedicated LED driver delivering 12v DC.
I wont use the bulbs until its swapped they were £4.75 each and dont want to do anything to risk limiting their lifespan.
I have extensively used gu10s around the house and first started with megaman 11w cfls but after 6 years 1/3rd of those have failed and as we redecorate rooms and as the cfls fail I am replacing with 240v gu10 leds which are now very good and can be had cheaply from proper suppliers.

 

[Mikefromlondon]

Ironically he sold him Powertran brand SMPS, which clearly says they are meant for halogen 12v lights!!!

So, at this stage, he should have taken them back as not fit for purpose sold for. Did he?

LOL! Would you take an item back if it is ripped out from its packaging and packaging discarded, since it cannot be sold to another customer? and for £4.00 for an item, is it worth the hassle, although in due honesty that shop would have most probably taken it back as he gets hundreds of customers, and contractors, so he probably wouldn't have had any problem taking it back, or simply swapped it with the right ones, but I buy stuff from this shop and next time i am in, I will have a word with him and he will be made aware of his mistake in selling a wrong PSU for an LED light.

And of course my mate would have gone back if he had not found those two WW power transformers that we managed to use and got perfect results.

 

[Mikefromlondon]

It is a bit annoying / ironic as I have spent many hours this week creating a design for pulse width modulated supply for LED lamps to make them intentionally flicker like a real candle flame in a lantern. Waxing and waning like a candle in the breeze and not just blinking on and off. Electronics simple, but designing the "random" flicker pattern was the hardest part. ( pseudo random, it repeats after about 15 hours ).

Are you trying to replicate Nature? I bought some electronic tea lights and these worked on a single CR2032 battery, and had a small push to latch switch at the bottom, and a yellow led housed in a small transparent plastic housing with the tip drawn to a point to look like a candle flame, and it had quite amazing effect, light dimming and flickering effect, though I never bothered trying to see if the pattern repeats, but no one is going to notice if it does in 10 minutes let alone in 15 hours!
All that flickering and dimming effect is built inside a tiny chip within the LED!

Amazing what electronic revolution has achieved.

 

[bernardgreen]

Being pendantic ( but it might help to be so )

The LED driver is the electronics in the lamp between the 12 volt power input terminals and the LED element(s). The LED driver controls the current through the LED element.

A power supply supplies power to the input of the LED lamp and then the LED driver takes what power it needs to drive the correct amount of current through the LED element.

A non dimmable LED driver will always try to supply the LED element with a constant current irrespective of the input voltage / waveform. ( that is as long as supply voltage is within the range the lamp is designed for )

A dimmable LED driver will look at the input power supply and from the voltage and/or waveform decide what current to drive through the LED element. The method used to determine how much current to put through the LED element when dimming the LED varies from make to make of lamp and driver.

 

[winston1]

Ironically he sold him Powertran brand SMPS, which clearly says they are meant for halogen 12v lights!!!

So, at this stage, he should have taken them back as not fit for purpose sold for. Did he?

LOL! Would you take an item back if it is ripped out from its packaging and packaging discarded, since it cannot be sold to another customer?

Most definitely. The sale of goods act says goods must be fit for purpose for which they are sold. The packaging (or lack of) is irrelevant.

 

[bernardgreen]

One further point.

Some electronic "transformers" are rated as 12 DC eff eff being short for effective. This invariable means the DC output is NOT steady 12 volts but some wavefrom that averages out to be 12 volts. Worst case one I have seem was a series of 36 volt pulses 1/3 ON and 2/3 OFF so the average was about 12 volts. The equipent it was feeding was not designed to take more than 15 volts on its power supply and failures were frequent. ( 25 volt capacitors failing ). That supply would work OK with filament lamps but not as a supply for electronic equipment such as LED drivers inside LED lamps rated at 12 volts DC supply

 

[JohnW2]

Being pendantic ( but it might help to be so )
The LED driver is the electronics in the lamp between the 12 volt power input terminals and the LED element(s). The LED driver controls the current through the LED element.
A power supply supplies power to the input of the LED lamp and then the LED driver takes what power it needs to drive the correct amount of current through the LED element.

To be even more pedantic, that "driver" can be external to the lamp as well as within the lamp. Some "LED drivers" are external constant-current sources, hence combining the functions of what you are calling a "driver" and a "power supply".

A dimmable LED driver will look at the input power supply and from the voltage and/or waveform decide what current to drive through the LED element. The method used to determine how much current to put through the LED element when dimming the LED varies from make to make of lamp and driver.

Indeed - and this is where most of the problems arise, and why comparability between power supply, dimmer, driver (whether within or external to the lamp) and the 'lamp' itself become important. For those who don't use a set of components specifically designed to work together (i.e. of the same manufacturer/'range') it can become a total lottery. In an ideal world, there would probably be more consistency/compatibility - but we don't live in an ideal world!

Kind Regards, John

 

[aveatry]

Here is a close up of the g4 led lamps does this give you any clue as to the electronics used, I notice that one side is marked + and the other - and didnt someone here say something about polarity but the thing is how would anyone know which is which in the fitting as it is not on it, there is nothing on the box on in the suppliers site about polarity.
I am thinking it is to do with the build because if you look at the - side you can see how it is put together - it is two flat sections with the smds and they have a slot so that one slots into another to create the x or cross shape so I would think it is so the Chinese girl on the production line slots them together the right way around.
Also which wasnt clear on the supplier site is the fact that it is totally encased in a silicon gel and so would be quite waterproof
Click on the picture for a very close look
View media item 96953View media item 96952

 

[ericmark]

I would agree a driver controls current, however for some reason the lighting industry seems to like using the wrong terms for things be it a driver, transformer, ballast or even lamp.

We the user has to do is try and work out what the item really is.

So
A driver rated at 340 mA at 3 ~ 12 volt is really a driver.
A driver rated at 0 ~ 340 mA at 12 volt is in fact a power supply.

Not a clue why manufactures call power supplies drivers but they do.

I have even seem 12 volt lighting sets called "Low Voltage" when we all know that is extra low voltage.

 

[JohnW2]

I would agree a driver controls current, however for some reason the lighting industry seems to like using the wrong terms for things be it a driver, transformer, ballast or even lamp. We the user has to do is try and work out what the item really is.

Indeed.

So ... A driver rated at 340 mA at 3 ~ 12 volt is really a driver.
A driver rated at 0 ~ 340 mA at 12 volt is in fact a power supply.

Quite. I personally try to avoid the word "Qdriver", instead calling those things "constant current power supplies" and "constant voltage power supplies" - but that doesn't necessarily help when the manufacturer calls something "a driver".

The whole thing obviously gets more complicated when dimming comes into the equation - since one can then get into such things as "variable constant-current supplies".

Kind Regards, John

 

[ericmark]

There seems to be two diodes at the bottom so it would seem likely to work either way around. DC normally means a smooth supply or at least the ripples as small, one would hope at least one capacitor in the power supply (often called incorrectly a driver). As already said the problem with an AC 12 volt RMS supply is the wave form does not need to be a sine wave so could mean 36 volt peaks.

Each LED needs around 3 volt so with a 12 volt supply having the LED's in groups of 3 means 9 volt for the LED's a 3 volt across a current limiting resistor and it does seem most 12 volt lamps have LED's in a multiple of 3's which seems to make sense.

In University one of the protects was to try and flash LED's at a frequency which was not visible to the human eye and over drive the LED's so to make them seem brighter. It was a failure as we had not worked out a way to emulate the human eye a lux meter just averages out the flashes so does not register them as being brighter. However a by product of the experiment did show you can over drive a LED by twice it's rating if you only power it for half the time. But the cycle was a lot shorter than with a 50 Hz supply.

The problem is we simply don't know what damage over driving does for a few microseconds, and any tests would need years to get the results. What we did find is once we did damage the diode it would not return to original brightness.

 

[aveatry]

There seems to be two diodes at the bottom so it would seem likely to work either way around. D.

If say that was not the case and it was polarity sensitive and I put it in the wrong way that what would happen

 

[JohnW2]

There seems to be two diodes at the bottom so it would seem likely to work either way around.

I'm far from convinced that they are diodes but, even if they are, I can't think of a way of achieving polarity-insensitivity with only two - that would surely require four? Is it possible that the four components labelled "85X" are diodes?

As has been said, it seems pretty unlikely that anyone would sell polarity-sensitive LED lamps unless they had some proprietary non-reversible holder, since there would otherwise be countless complaints of the lamps 'not working'.

If (and I doubt it) there are some polarity-sensitive DC ones around, then applying AC would presumably carry the risk of exceeding the reverse-potential limit (PIV) of the LED, thereby possibly destroying it?

Kind Regards John