home > Internet > Converting a fluorescent lamp into an LED lamp. How to replace a U-shaped fluorescent lamp with LEDs in a table lamp DIY conversion of a table lamp to LED

Converting a fluorescent lamp into an LED lamp. How to replace a U-shaped fluorescent lamp with LEDs in a table lamp DIY conversion of a table lamp to LED

The modern small-sized table lamp, which is shown in the photograph, with a light source installed in it in the form of a fluorescent U-shaped compact lamp, worked for several years and failed.

According to the owner table lamp, recently, when the lamp was still working, there was an unpleasant smell coming from its base.

Opening the base of the lamp immediately showed what the problem was. The insulation in one of the windings of the ballast device was burnt. Apparently from overheating or Bad quality insulation of the winding wire of the coil, a short circuit occurred between the turns, which provoked the heating of the winding to a high temperature and the final failure of the ballast device.

I didn’t want to bother with rewinding the coils, and it was almost impossible to find a ready-made ballast device for replacement, especially since its type was unknown. Therefore, I decided to remake the table lamp in a modern way - install LEDs instead of a fluorescent lamp, and replace the ballast device with an electronic driver, especially since everything for such a remodel was at hand.

Replacing a fluorescent lamp with LEDs

There was a long and narrow printed circuit board with LEDs from a linear LED lamp.

The driver in it burned out and melted the tube body due to heat. Therefore, the linear lamp could not be repaired, but the diodes were in good working order. The width of the strip with LEDs fit well into the reflector of the table lamp.

The fluorescent U-shaped tube in the reflector was held in place by a plastic retainer and a base. To determine the required length of the LED strip, the lamp and base had to be removed. In order to get to the base of the fluorescent lamp, I had to unscrew one screw and remove the fixing strip.

The base did not have any additional fastening, and to remove it all that remained was to unsolder the two supply wires. The wires were multi-core and of sufficient cross-section, so I decided to leave them to supply power to the LEDs.

After trying on and determining the length of the LED strip, a piece of the required length was cut off using a jigsaw. The LEDs on the bar are placed diagonally, so I had to cut them with a jigsaw.

The cutting line passed into in the right place, the printed tracks connecting the LEDs remained intact.

To attach the LED strip, we used the existing fasteners for the table lamp reflector. The fluorescent lamp was fixed using a plastic bracket screwed to the reflector with a self-tapping screw, and the fixing cover was screwed to the plastic stand.

A hole with a diameter of 3 mm for a self-tapping screw was drilled in the strip between the LEDs and a hole was made for fastening to the stand. After checking that the mounting hole matches the hole in the short stand, you can begin to secure the strip with LEDs in the reflector.

Before final installation of the strip with LEDs in the reflector, it is necessary to solder wires to the contact pads on it. One of the wires was short, and it had to be extended by soldering and an insulating casing put on the connection point. Since the wires were the same color, after checking with a multimeter, the positive wire was marked on both sides with white cambric rings.

I used a ready-made PCB with LEDs. But it’s easy to make such a board yourself. Moreover, if you use modern one-watt LEDs, for example LED-SMD5730-1, then it is enough to solder only 3-5 pieces. You can also use an LED strip glued to a metal strip as a light source instead of individual LEDs. You will have to select a driver individually in each case.

The photo clearly shows how a printed circuit board with LEDs installed on it is fixed in the reflector of a table lamp. In order for the bar to be removed from the bottom of the reflector at the long post (photo on the left), a cambric with a length equal to the height of the right short post was put on it.

Before fixing the LEDs in the reflector, they were tested by connecting to the driver. The current consumption was also measured. The photo shows a reflector with LEDs installed in it. All that remains is to attach the fixing cover, having first placed a piece of cambric over its entire length on the protruding post. Thus, the left edge of the bar will be securely fastened between two sections of tubes.

Driver selection and circuit diagram

To supply power voltage to the LEDs, a transformerless driver from a faulty E27 LED lamp, assembled according to a classic electrical circuit diagram, was used.

In the photo you can see the wiring to the driver. Black wires coming from the LED board are soldered to the positive and negative outputs of the driver. Using blue and yellow wires, a supply voltage of 220 V is supplied to the driver.

Electric circuit diagram driver is given above. Capacitor C1 with a capacity of 0.8 μF limits the current to 57 mA. R1 and R3 limit current surges due to the charging of capacitors when the driver is connected to the network. The diode bridge VD1-VD4 rectifies the voltage, and the electrolytic capacitor C2 smoothes out the ripples so that the LEDs do not blink at the mains frequency. A safety element is also installed in the driver circuit, most likely it is a barter; it smoothes out current surges and at the same time acts as a fuse. If you need to reduce or increase the LED supply current, you will need to correspondingly reduce or increase the capacitance of capacitor C1. You can increase C1 even without desoldering it from the board by soldering an additional capacitor in parallel to its terminals. When capacitors are connected in parallel, the total capacitance is equal to the sum of their capacitances, that is, the current will also increase.

The constant current that ensures optimal brightness of the LEDs used is 20 mA. LEDs on printed circuit board connected in parallel in three pieces. Therefore, the current required for their operation according to such a connection scheme should be 60 mA. As you know, for long-term operation of LEDs it is better that the flowing current is slightly less than the rated current. Therefore, a current of 57 mA provided by the driver fully satisfies this requirement.

There were 60 LEDs on the strip. The measured voltage drop across each triad of LEDs was 2.48 V. Thus, the power consumed by the LEDs was 2.48 V × 20 pcs. × 0.057 A = 2.8 W, which is equivalent to a 25 W incandescent light bulb. The illumination created by the table lamp is quite sufficient when used as an emergency light, a night lamp, a backlight for a computer keyboard, or for reading an e-book.

The weight of the driver is insignificant and therefore I did not mount it rigidly, I simply grabbed it with a flexible plastic clamp by one of the posts for attaching the halves of the base. The standard table lamp switch was used as a switch. To complete the modification of the table lamp, all that remains is to fasten its base together with three self-tapping screws, and you can begin to carry out sea trials.

Tests of the table lamp showed good results. Thanks to the ability to tilt the stand and rotate the reflector in two planes, the table lamp allows you to direct the light flux to the desired lighting area.

The alteration made it possible not only to restore the functionality of the table lamp without cost, but also turned an obsolete table lamp into a modern lamp with low energy consumption.

If the old Soviet lamp with fluorescent lamps daylight type LB-40, LB-80 has failed, or you are tired of changing the starter in it, recycling the lamps themselves (and you can’t just throw them in the trash for a long time), then it can easily be converted into an LED one.

The most important thing is that fluorescent and LED lamps have the same bases - G13. Unlike other types of pin contacts, no modifications to the housing are required.

G- means pins are used as contacts

13 is the distance in millimeters between these pins

Benefits of remodeling

In this case you will receive:

greater illumination

lower losses (almost half of the useful energy in fluorescent lamps can be lost in the choke)

absence of vibration and unpleasant rattling sound from the ballast throttle

True, in more modern models, it is already used electronic ballast. They have increased efficiency (90% or more), noise has disappeared, but energy consumption and luminous flux have remained at the same level.

For example, new models of such LPO and LVO are often used for Armstrong ceilings. Here is a rough comparison of their effectiveness:

Another advantage of LEDs is that there are models designed for supply voltages from 85V to 265V. For fluorescent you need 220V or close to it.

For such LEDs, even if your network voltage is low or too high, they will start and shine without any complaints.

Luminaires with electromagnetic ballasts

What should you pay attention to when converting simple fluorescent lamps to LED lamps? First of all, its design.

If you have a simple old Soviet-style lamp with starters and an ordinary (not electronic ballast) choke, then in fact there is no need to modernize anything.

Simply pull out the starter, select a new LED lamp to fit the overall size, insert it into the housing and enjoy brighter and more economical lighting.

If the starter is not removed from the circuit, then when replacing the LB lamp with an LED one, a short circuit can be created.

It is not necessary to dismantle the throttle. For an LED, the current consumption will be in the range of 0.12A-0.16A, and for a ballast, the operating current in such old lamps is 0.37A-0.43A, depending on the power. In fact, it will act as an ordinary jumper.

After all the rework, you still have the same lamp. There is no need to change the fixture on the ceiling, and you no longer have to dispose of burnt lamps and look for special containers for them.

Such lamps do not require separate drivers and power supplies, since they are already built-in inside the housing.

The main thing is to remember the main feature - for LEDs, two pin contacts on the base are rigidly connected to each other.

And with fluorescent they are connected by a filament. When it gets hot, mercury vapor ignites.

In models with electronic ballasts, a filament is not used and the gap between the contacts is pierced by a high voltage pulse.

The most common sizes of such tubes are:

300mm (used in table lamps)

900mm and 1200mm

The longer they are, the brighter the glow.

Conversion of a lamp with electronic ballast

If you have a more modern model, without a starter, with an electronic ballast throttle (electronic ballast), then you will have to tinker a little with changing the circuit.

What is inside the lamp before alteration:

throttle

wires

contact blocks-cartridges on the sides of the case

The throttle is what will need to be thrown out first. Without it, the entire structure will significantly lose weight. Unscrew the mounting screws or drill out the rivets, depending on the fastener.

Then disconnect the power wires. To do this, you may need a screwdriver with a narrow blade.

You can use these wirings and just eat them with pliers.

The connection diagram for the two lamps is different; with the LED lamp everything is much simpler:

The main task that needs to be solved is to supply 220V to different ends of the lamp. That is, the phase is on one terminal (for example, the right one), and the zero is on the other (left).

It was said earlier that an LED lamp has both pin contacts inside the base, connected to each other by a jumper. Therefore, here it is impossible, as in a fluorescent one, to supply 220V between them.

To verify this, use a multimeter. Set it to resistance measurement mode, and touch the two terminals with the measuring probes and take measurements.

The display should display the same values as when the probes are connected to each other, i.e. zero or close to it (taking into account the resistance of the probes themselves).

A fluorescent lamp, between two terminals on each side, has a resistance filament, which, after applying 220V voltage through it, heats up and “starts” the lamp.

without dismantling cartridges

with dismantling and installing jumpers through their contacts

Without dismantling

The easiest way is without dismantling, but you will have to buy a couple of Wago clamps.
In general, bite out all the wires suitable for the cartridge at a distance of 10-15mm or more. Next, insert them into the same Vago clamp.

Do the same with the other side of the lamp. If the wago terminal block does not have enough contacts, you will have to use 2 pieces.

After this, all that remains is to feed a phase into the clamp on one side and zero on the other.

No Vago, just twist the wires under the PPE cap. With this method, you do not need to deal with the existing circuit, jumpers, get into the cartridge contacts, etc.

With dismantling the cartridges and installing jumpers

The other method is more scrupulous, but does not require any extra costs.

Remove the side covers from the lamp. This must be done carefully, because... In modern products, the latches are made of brittle and breakable plastic.

After which, you can dismantle the contact cartridges. Inside them there are two contacts that are isolated from each other.

Such cartridges can be of several varieties:

All of them are equally suitable for lamps with G13 socket. There may be springs inside them.

First of all, they are needed not for better contact, but to ensure that the lamp does not fall out of it. Plus, due to the springs, there is some compensation for the length. Since it is not always possible to produce identical lamps with millimeter accuracy.

Each cartridge has two power cables. Most often, they are attached by snapping into special contacts without screws.

You turn them clockwise and counterclockwise, and with some force, pull one of them out.

As mentioned above, the contacts inside the connector are isolated from each other. And by dismantling one of the wiring, you actually leave only one contact socket.

All current will now flow through the other contact. Of course, everything will work on one, but if you are making a lamp for yourself, it makes sense to improve the design a little by installing a jumper.

Thanks to it, you don’t have to make contact by turning the LED lamp from side to side. The double connector ensures a reliable connection.

The jumper can be made from unnecessary wires power supplies for the lamp itself, which you will definitely have left over as a result of the rework.

Using a tester, you check that after installing the jumper, there is a circuit between the previously isolated connectors. Do the same with the second plug-in contact on the other side of the lamp.

The main thing is to make sure that the remaining power wire is no longer phase, but zero. You bite off the rest.

Fluorescent lamps with two, four or more lamps

If you have a two-lamp lamp, it is best to supply voltage to each connector with separate conductors.

When installing a simple jumper between two or more cartridges, the design will have a significant drawback.

The second lamp will light only if the first one is installed in its place. Remove it, and the other one will go out immediately.

The supply conductors should converge on the terminal block, where you will have the following connected in turn:

For any work, as well as during rest, you need good light. You can buy a lamp, but sometimes it is not cheap. In the store, instead of a ready-made lamp, you can purchase an LED strip. It is relatively inexpensive and can be cut into pieces of any length. If you place it in the case or secure it in another way, you will get homemade lamp with LED strip. You can take this lamp with you to your tent when fishing. When traveling, the LED lamp is connected to a car battery.

Scope of application of homemade LED lamps

Homemade LED lamps for LED strip can be used instead of conventional ones:

illumination of the workplace when performing small work in a workshop or garage;
lighting on top of the aquarium (if the tape is waterproof or in sealed housing, then the lamp can be lowered into water);
illumination of seedlings or indoor plants in winter;
night light or table lamp;
lighting of switches and sockets;
computer keyboard lighting;
for replacing fluorescent lamps.

On the Internet you can find many other types of floor lamps and ceiling chandeliers from LED strip with photos and videos, as well as reviews from people who collected and used such lamps.

Types and parameters of LED strips

LED strip color options

LED strips are available in different designs depending on the type of protection. They can be of different brightness and different colors, which are determined by color temperature - from warm white (2700K) to cold (6800K), as well as colored or capable of changing their color - RGB tapes. This makes it possible to select the type of device for specific purposes.

LED strip device

LED strip is a flexible plastic strip with conductive strips printed on it. Two are located at the edges and connections are made to them. The rest connect LEDs and resistors to each other. They are arranged in groups - three LEDs connected in series, and a resistor that serves to limit the current flowing through them.

LED strip parameters

The strip itself can be cut into sections that are multiples of three LEDs. In these places there are marks indicating the place of the cut and the contact pads to which the wires are soldered or connected using connectors.

LEDs can be coated with a layer of silicone on one or both sides. This determines the degree of protection against external influences. On the reverse side, an adhesive layer is applied to the strip, like on double-sided tape. With its help, the LEDs are attached to the base.

The most common supply voltage is constant, 12V. There are designs designed to connect to a voltage of 24V and higher, but these are not very common designs.

Types of LEDs used

LEDs and resistors in the strip are used in the SMD series, without leads. LEDs in production are used in different sizes, which determines the marking of the strip - 5050 and 3528. These numbers show the size of the LED in tenths of a millimeter

Visual difference between 5050 and 3528

Expert opinion

Alexey Bartosh

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The larger the size, the higher the brightness and the current and power consumption. It also depends on the number of LEDs per meter of length.

Accordingly, marking an SMD 5050 strip with a density of 60 LEDs means that 60 SMD 5050 LEDs are installed per meter of length.

Controllers, power supplies for LED strips

controller and power supply

Since the LED strip is designed for constant pressure 12V, then a power supply or controller is required for connection.

Important! When you connect the LED strip to a 220 volt network, it will instantly burn out!

Power supplies are produced in different capacities and shapes. From low-power, similar to charging device from tablet to powerful designs in metal case with built-in coolers.

LED strip power supply power

Some power supplies are equipped with dimmers and remote controls remote control. RGB strips require an RGB controller to control color.

There are models controlled via WiFi, with color and music effects, for example, ARILUX® AL-LC01.

If you don’t have a special block available, you can use:

Any transformer with an output voltage of 12V. Must be connected to the output diode bridge and a smoothing capacitor.
The computer power supply, both in the computer itself and separately.
If you need 3-6 LEDs, then to limit the current you can use a capacitor, as well as a diode bridge and a capacitor that smoothes out the pulsations of the glow. This scheme is used in LED lamps installed instead of incandescent lamps. The capacitance of the capacitor can be calculated using an online calculator.
Make an energy-saving lamp out of the board of a faulty lamp.
Connect 20 pieces of LED strip in series and connect through a diode bridge and a smoothing capacitor to a 220V network.

Preparation of materials and parts

making a lamp with your own hands

Before starting work, you need to determine the required number and brightness of the LED strip, as well as the power of the power supply.

First of all, you need to determine the length. For lamps used in different places you need:

night light and illumination of switches and sockets - a segment of three LEDs;
aquarium lighting – along the length of the wall;
illumination of a bed with seedlings - several pieces, a length equal to the length of the beds;
computer keyboard – along the length of the keyboard;
To replace a fluorescent lamp, you need several pieces, equal in length to the length of the lamp.

The brightness of the strip, the size and density of the LEDs are determined based on specific conditions.

The power of the power supply must be no less than the power LED lamp, and preferably 20% more. This is necessary for more reliable operation of the unit.

In addition, you will need wires, heat shrink tubing to insulate the connection point, a soldering iron with tin and rosin, or a connector for connection.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

Ask a question to an expert

Attention! You cannot solder the tape with acid! Acid fumes oxidize and destroy wires and can also cause short circuits.

If the lamp will be used in an aquarium for internal lighting, then you will need a transparent tube and silicone sealant to ensure the tightness of the structure. After developing the design of the future lamp and preparing all the tools and materials, the lamp itself is assembled.

Sometimes the entire assembly process involves applying tape to a base, such as a backlit keyboard that sits on a pull-out shelf under a desk.

In other cases, it is necessary to manufacture or remodel an existing lamp.

Features and stages of installation work

Installation and connection of a lamp made from LED strip has a number of features:

The power supply should be located as close to the LEDs as possible. The longer the wires, the greater the voltage loss in them, which leads to a loss of brightness of the lamp.
It is advisable to isolate the LEDs from the base if it is metal.
When connecting the device directly from a 220V network (via a capacitor), use only a tape coated with silicone on both sides.

Carefully! On such a tape there is high voltage, therefore all manipulations with it are performed in the disabled state.

What to do if there is no ready-made LED strip

If you don’t have a ready-made LED strip, you can make it yourself.

To do this, the required number of LEDs must be connected in series and a current-limiting resistor connected to them. You can assemble such a structure on a strip of getinax or textolite, where holes are drilled for mounting LEDs. Such a device can be assembled for any required voltage and number of LEDs.

I bought 10 W 900 lm warm white LEDs on AliExpress to try. The price in November 2015 was 23 rubles per piece. The order arrived in a standard bag, I checked everything was in good condition.

To power LEDs in lighting devices, special units are used - electronic drivers, which are converters that stabilize the current rather than the voltage at their output. But since the drivers for them (I also ordered on AliExpreess) were still on the way, I decided to power them from ballast from energy-saving lamps. I've had several of these faulty lamps. whose filament in the bulb burned out. As a rule, the voltage converter for such lamps is working properly, and it can be used as pulse block power supply or LED driver.
We disassemble the fluorescent lamp.

For the conversion, I took a 20 W lamp, the choke of which can easily deliver 20 W to the load. For a 10W LED, no further modifications are required. If you plan to supply more powerful LED, you need to take a converter from a more powerful lamp, or install a choke with a larger core.
Installed jumpers in the lamp ignition circuit.

I wound 18 turns of enamel wire around the inductor, solder the terminals of the wound winding to the diode bridge, apply mains voltage to the lamp and measure the output voltage. In my case, the unit produced 9.7V. I connected the LED through an ammeter, which showed a current passing through the LED of 0.83A. My LED has an operating current of 900mA, but I reduced the current to increase the resource. I assembled the diode bridge on the board using a hinged method.

Remodeling scheme.