Good afternoon, Muska readers! Below we will present an overview of LED lamps with a G4 connector, which have 24 LEDs of size 2835 on board and a declared power of 3 W.
So, I had a chandelier in my hall that used fifteen twenty-watt halogen lamps for lighting, ultimately consuming about 360 W. Due to the constant increase in electricity tariffs and the appearance of many reviews of LED lamps on MYSKU, I decided to try similar lighting at home. Since halogen lamps are powered by an alternating voltage of 12V (there are two transformers of 160W each), it was decided not to change the factory circuit of the chandelier and purchase lamps designed for 12 VAC with a built-in driver and with more or less recent/powerful 2835 LEDs. Moderate power was also chosen (3W in brightness in my imagination corresponded to a 20W halogen lamp) and small dimensions (not 48 LEDs 3014 for example) due to the design of the chandelier so that the lamp would slightly protrude from the “flowers”, the color is warm white (2700-3000K). Next, the corresponding light bulbs were found on taobao.com and ordered through an intermediary in the amount of 10 pieces.
A month later the lamps were received, and I began to examine them.
Comparative dimensions of lamps and boxes:
The weight of the lamp was 5 grams.
Lamp close up:
So, the lamp contains 24 2835 LEDs, a PT4115 driver, 4 diodes that make up the input bridge, a 100 µF tantalum capacitor, a 47 µH inductor, a Schottky diode and a 0.56 Ohm current-setting resistor. The diagram almost completely corresponds to the driver datasheet and looks like:
The load current is found by the formula: IL=0.1/R1. In our case, we have IL=0.1/0.56=0.179A, which already gives rise to some thoughts. LED connection – 3S8P.
Next, the lamps were installed in the chandelier (do not forget that the chandelier has 15 lamps, 5 of which remain halogen). I’ll say right away that I’m far from an amateur photographer, and the Samsung ST96 camera is quite old and does not have the ability to set the shutter speed manually, so I present two photos with ISO100 and ISO800 (if that means anything at all))) with an “incandescent” white balance .
To my untrained eye, the brightness of the new lamps is almost the same as the halogen lamps (5 in the center), since the lamps emit warm white light, the difference in the glow temperature is practically not felt. There is no flicker.
Well, now let's start practical testing of the lamps. Let's determine the current consumption (source - power supply 12VDC 2A):
The current consumption was 154.7 mA, so the power consumption was P=UI=0.1547x12.51=1.92 W, which is less than the declared 3 W. Next, let's see whether such a limitation on the power of the LEDs was reasonable (the nominal power of 24 LEDs 2835 is 4.8 W), for which we look at the temperature of the LEDs:
As you can see, the temperature of the LEDs exceeds 90 degrees and is quite close to the maximum allowed pn-junction temperature for 2835 (125 degrees), which raises some concerns about their future fate (so far there have been no “victims” in two weeks of testing). The lamp itself is filled with transparent sealant, you can take it by hand, even in working condition, without any fear - it is barely warm. On the other hand, the temperature of the XM-L T6 diodes in the Trustfire 3T6 flashlight easily exceeds a hundred, but the flashlight has been fine for two years, although the maximum transition temperature there is higher - 150 degrees.
Well, it’s time to wrap things up, so I’ll move on to the conclusions.
+ The brightness of the lamps corresponds to 20 Watt halogen lamps;
+ Pleasant warm light;
+ High-quality circuit design;
- The power does not correspond to the declared one (1.9 W versus 3 W);
- High temperature of LEDs (due to this reduced resource).
In general, I recommend these lamps, but to save money I would advise replacing the transformer for halogen lamps with a constant voltage source and buying lamps designed for 12 VDC - they will cost much less, since they only have a current-limiting resistor instead of a driver with wiring.
I'll take my leave then, thank you for taking the time to read! I'm planning to buy +15 Add to favorites I liked the review +16 +45
There are several 12V luminaires that have successfully used QT9 (G4) halogen bulbs for more than 5 years. There was only one drawback - significant heating of the lamp body. Since the LED strip has been successfully used for more than 2 years for 6 - 8 hours, the diode light bulb from Ikea works great, I decided to try changing the halogens to LEDs.
In addition, similar products were already reviewed here, which contributed to the purchase.
Since the blame for the described defect lies on my conscience, please read this review with PS.
The purchase was made, and 2 lamps were ordered - one cold, the other warm white light. Delivery took place quite quickly, took less than a month.
When opening the yellow package, 2 perfectly preserved boxes were discovered, completely identical in appearance. 
This alarmed me - after all, I asked to send me lamps that differ in spectrum. Then I tried to turn them on - yes, they differed in spectrum, although they had the same boxes. The power was weaker than the previous 10 W, as predicted.
The seller received positive feedback.
The only thing I didn’t like was that the “bulb” was not made of glass, but of some kind of soft plastic, reminiscent of silicone. 
When heated, there was naturally a smell, but not so strong. Speaking of heating, the body of the lamp did not heat up at all, although the body of the light bulb got quite hot. The temperature was naturally lower than that of the previous lamp - I could remove its replacement with my hands immediately after turning it off. The length of the purchased product did not allow me to attach the protective glass to the lamp, but I was ready for such a development of events.
Now about the most important thing.
The first light bulb, after working for several days, switched to a pulsating mode of light flux visible to the eye, which made us remember the old Soviet fluorescent lamps with their inherent stroboscopic effect, especially not long before the natural end of their life cycle. The lamp from Ikea had no trace of this, nor did the LED strip from ebay.
Okay, I thought. And installed a second light bulb. This one was even less pleasing to the eye - after a couple of hours it repeated all the depravity of the first.
I tried to put them in another lamp, but the disease, which arose suddenly, began to manifest itself immediately, i.e. no connection could be traced either from the lamp or from the degree of heating.
I had to put everything back together as it was originally, go finish reading the book (by the way, I recommend it) “Bad Made in China” by Paul Midler and think: somewhere to adapt the defective goodness.
It would probably be better to buy this:
Pros:
Fast delivery
Low price
Low heat dissipation
Minuses:
Somewhat non-standard dimensions
Normal service life measured in hours. It really is “Aliis inserviendo consumor”
A conclusion that I have come to more than once, but forgot this time. Before leaving positive feedback to the seller, use the purchased device for a while. This time I forgot about it, for which I was fined 60 rubles ($1). But I once again understood why sellers have so many positive reviews for some products.
I don't recommend buying it.
Happy shopping everyone.
In the absence of a kote - a photograph of my hometown (taken with my own hand) 
And now PS:
The opinions of many respected mysku readers prompted us to look into the problem. It turned out that the reason was quite obvious and lay in my deep and erroneous belief that the lamp transformer generates constant voltage. That is why I ordered, quite deliberately, DC type bulbs. It turned out that the transformer supplies an AC output voltage of 13.8 V, which naturally requires AC bulbs.
Moreover, the light bulbs connected to a stabilized power supply producing 12 V DC glowed without flickering. Thus, all the blame in the story described lies entirely on my conscience. I sincerely and deeply apologize to the Chinese comrades who manufactured such durable devices and to respected admirers of the resource for the distorted information about the product. Special thanks to those whose comments helped to understand the situation and establish the truth.
Surely, many owners of chandeliers or spotlights with halogen bulbs have more than once thought about replacing them with LED analogues. Mainly due to significant energy savings. However, it is not always possible to assess in advance whether such an exchange is really necessary. And in this article I want to show in practice what gives Replacing halogen lamps with LED lamps using the example of light bulbs with G4 socket.
Here are different types of light bulbs, but all with g4 socket
The top row shows halogen and LED bulbs for 220V, and the bottom row contains the same representatives, but for 12V. It is clearly noticeable that the dimensions of 220V lamps are slightly larger than 12V lamps.
Two types of LED light bulbs with a G4 socket - on the left is a light bulb with a single powerful LED and a diffuse lens, and on the right is a lamp with many LEDs, popularly called “corn”
What will we get from replacing a G4 halogen bulb with an LED one?
If we take a closer look at halogen and LED lamps, we will see that the filament in a halogen lamp is located closer to the base. While the emitting LED in an LED lamp is located much further from the base. As a result, we get a completely different lighting halo when using different types of lamps.
The left lampshade with a halogen lamp is fully illuminated,
while the LED light in the right lamp only illuminates its outer edge
Here the halogen light also brightly illuminates the entire chandelier shade,
and the LED bulb does not illuminate the lampshade at all
For now, the advantages of halogen lamps are obvious, but we will not rush to conclusions and will continue our experiments on replacing halogen lamps with LED ones.
Let's compare halogen light bulbs designed for 220V and 12V.
On the left, the 220V halogen lamp glows yellow,
and on the right the 12V halogen produces a white light that appears brighter.
Perhaps for this reason, most chandeliers and spotlights with compact shades and a G4 base are designed specifically for 12-volt halogens.
Let's look at how LED lamps of different voltages behave.
On the left, the 220V LED corn lamp lights up yellow,
and on the right is a lamp with a diffuse lens, but at 12V it gives white light
Important points when replacing a halogen lamp with an LED lamp with a g4 base
When replacing a halogen lamp with an LED analogue, it is necessary to take into account the following, in my opinion, the most important feature. A halogen lamp is essentially an incandescent lamp that shines in all directions. And the LED emits light only in one direction, which in space looks like a light cone. This is why almost all single LED bulbs have a diffuser lens. However, for some types of spotlights and chandeliers, a diffuser lens may not be effective. In this case, an omnidirectional LED corn lamp can partially correct the situation.
A striking example of comparing halogen and LED lamps in a chandelier with small shades
Now let’s compare the shape and size of the light spots produced by LED lamps of different designs.
In the photo from left to right: LED corn lamp, LED lamp with one LED and a diffuser lens, LED lamp with one LED but without a diffuser lens
As you can see, in this case, at the same power, a redistribution of the light flux occurs. In corn lamps, the luminous flux is close to a halogen lamp, and lamps with and without a lens have an increasingly concentrated luminous flux. This causes the illumination directly below the luminaire to appear stronger, while the overall illumination of the room appears insufficient.
Therefore, in this particular case, it is advisable to replace halogen lamps with LED “corn” lamps only in connection with the opportunity to save money on electricity.
In some types of lamps, due to the shape of the lampshade, even a halogen lamp sticks out, and when using its LED analogue, the protrusion of the light source becomes even more noticeable. When turned on, there is a change in brightness, and for the worse.
The central lampshades are illuminated by halogen lamps, which stick out slightly, the remaining lampshades are illuminated by LED lamps with one LED
Here we cannot say that it has become darker; rather, a redistribution of light has occurred. The spots on the ceiling have disappeared, the glass elements are less filled with light, however, under the chandelier itself there is more than enough light, which cannot be said about the room itself. It's all due to the direction of the LED glow.
The pitfall of replacing halogen lamps with LED lamps
When replacing halogen lamps with LED lamps, the following feature was discovered: 220V LED lamps shine brighter than 12V lamps with the same power and luminous flux. What causes this anomaly, since the LED itself is a low-voltage device and operates on several volts, just remember the famous LED strips?
Let's try to figure it out. LEDs operate on constant current. LED lamps designed for 220V inside have a miniature rectifier with a stabilizer, so they can operate on alternating voltage. In 12V LED lamps there is no rectifier, but there is always a diode bridge, which allows you not to worry about the switching polarity, but does not provide the declared brightness when operating on alternating current. Therefore, 12V LED lamps must operate on constant current, which can be provided by a special power supply or LED driver. And in halogen lamps, where we want to replace the lamp with an LED one, a special transformer is installed to power low-voltage halogen lamps, which is not intended for LEDs. That is, additional costs are required to purchase and replace the transformer with an LED driver.
LED drivers for LED lamps and transformer for halogen lamps
What to do? Either come to terms with it and use higher-power analogues, or, best of all, replace that same “halogen” transformer with an LED power supply. But then you need to change all the lamps from the chandelier at once, not forgetting the design features of LED lamps.
When I was just planning to replace the halogen light bulbs in my apartment with LED ones, I watched several videos that were clearly in favor of LED sources, but in practice it turned out not to be so simple. Replacing halogen bulbs with LED ones does not always make the room brighter - the shape and size of the spotlight itself or the lampshade in the chandelier plays a big role here. I hope my article helped you decide whether you need such a replacement.
LED light sources with base G4, are the smallest and quite economical compared to similar ones. Due to its shape and low energy consumption, this type of lamp is widely used in various fields of human activity. One of the main tasks LED lamps with G4 socket is a replacement for halogen light sources.
Firms offer the user a high-quality and economical option LED lamps. These companies were able to place a large number of LEDs in a small housing, which has the same parameters as a halogen lamp. By using many economical LEDs, manufacturers were able to obtain an economical lamp that can produce a very high luminous flux. Due to this, LED lamp with G4 socket On average, it has a power of 3W, and the luminous flux it produces reaches 200Lm. Halogen lamp to obtain such a luminous flux it must have a power of about 10W, and therefore it becomes unprofitable compared to an LED light source.
They are mainly used in shops, hotels, lobbies, restaurants, any public places, and are also widely used in human everyday activities. Due to its minimal size, this type of lamp is often used by designers to create lighting effects. There are a lot of light compositions, wall or ceiling, where they are used to create a pattern or frame. LED lamps with G4 socket. Also, these lamps do not emit heat during operation, which means that they can be used to illuminate objects that critically respond to thermal influences.
Mainly due to this property, such LED bulbs used in museums to illuminate paper or other exhibits. Also, due to the lack of heat generation during operation, this type of lamp is widely used by shops and restaurants that illuminate food or various prepared foods.
Installation LED lamps is very easy to do because base G4 these are just two metal pins that need to be inserted into the groove of the cartridge. When replacing with an LED light source, the user does not need to install the socket to the electrical network, but simply remove and insert the diode.
LED lamp with G4 socket Compared to it does not have an ignition stage, and the user instantly receives 100% luminous flux. Halogen lamp when turned on, it cannot immediately produce a full luminous flux; also, during operation, this lamp loses performance, which is expressed in the loss of intensity of the transmitted light beam. LED lamp has no such problems. Life time LED lamp 15 times more than halogen light sources. This means that when using halogen lamps, the user will constantly incur expenses for new light sources, as well as constantly pay for their installation, which is irrational and much easier to use LED lamp, which does not require this maintenance and costs.
There is a good table lamp. It contains a halogen light bulb with a G4 base and 12V. Something like this
Moreover, the light bulb is protected by a glass shield. That, however, did not prevent the daughter from touching the shield with her finger and getting burned. I scratched my head - shouldn't I replace it with an LED with the same base? I googled it and got upset. It turns out that the so-called halogen lamps are widely used. electronic transformers not suitable for LEDs. People write en masse about replacing them with LED lamps specially designed for power supply. Okay, extra money - 10 bucks won't make a difference. But first of all, the base of the lamp where the transformer is inserted is quite compact and a replacement will not fit. And secondly, and even more importantly, the most ordinary trance standing there on an W-shaped core, with its significant weight, makes the lamp stable. If I replace it, it will fall.
Sadness...
I started making things up. The first thing that comes to mind, of course, is to leave the trans only for weight and find a 220B lamp. And the Chinese found them. And then in Leroy there is one, at 220B. It can be seen that in front of the LEDs there is a chip with 4 legs. The markings are not visible, but of course - a diode bridge (they sell it in chip and dip for 11 rubles each). The LEDs themselves are clearly connected in series.
Looks like this is the solution! But, after thinking about it, I discarded this idea. Nobody promised me that the wire and base in which I now have a 12V halogen are designed for 220. That is, change. And this is a disproportionate gimor. We are looking further.
I found the same diode bridge on the chip and dipstick, tiny, it will fit in without any questions. I set out to study the choice of the necessary piping, a smoothing capacitor at least. And I came across a mention of 12 volt AC/DC lamps! Stsuko, that’s exactly what I need! Now, I know, I’m looking in the same Leroy - there is one for 12V AC/DC. No wonder I didn’t notice it right away - the title LED lamp WOLTA 2.5W 210Lm G4 12V warm. And it’s only written about AC/DC in the picture with the packaging! Stsuko, how tired I am of the widespread dominance of C students! Well, okay, imbeciles were recruited by advertisement to work in the hall; I haven’t spent time talking to them for many years. But a huge network made a catalog for itself on the website. Didn’t it really surprise you that they forgot to mention the operating voltage in the table of lamp characteristics? Printed in huge letters on the box, motherfucker.
PT415 is clearly readable on the chip. Which is easy to Google. The first assignment line is for replacing halogens with LEDs. The microcircuit even supports dimming - but it was not used in this assembly. I'm going to buy food.
I bought it, the only thing is that I mixed up warm and cold light, but it’s even better in a table lamp. Interestingly, the light bulb does not have a bulb as such. Filled with transparent plastic resin.
As expected, in a lamp with a real transformer with an W-shaped core, it burns perfectly. True, as expected, it does not respond to changes in the input voltage (there are two taps on the trance - for the maximum brightness of the halogen lamp and a weaker one).
At the same time, I tested it in a closet, where there are three halogen lights in the visor. There is an electronic "transformer". Everything is as people write. If there is at least one halogen, the LED lights up perfectly. If there is only one LED left, it lights up brightly, but flickers. So you will have to either leave the halogens or buy an LED driver. It’s good that there’s enough space at the top of the closet.
UPD from September 17, 2016 My wife said that the brightness in the table lamp is not enough. 2.5 W bulb, maybe... I found a 10 W LED bulb with 600 lm. Most of them are 5 and 300. Now there is enough light.
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