How to replace a U-shaped fluorescent lamp in a table lamp with LEDs. Driver for LEDs from an energy-saving lamp How to convert a fluorescent table lamp to LED

At 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 finished lamp, you can purchase led strip. It is relatively inexpensive and cut into pieces of any length. If you place it in the case or fix it in another way, you get homemade lamp with LED strip. You can take such a lamp with you to a fishing tent. In field conditions, the LED lamp is connected to a car battery.

Scope of homemade LED lamps

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

• illumination of the workplace when performing minor work in the workshop or garage;
• lighting from above the aquarium (if the tape is waterproof or in sealed case, then the lamp can be lowered into the water);
• illumination of seedlings or indoor plants in winter;
• night light or table lamp;
• illumination of switches and sockets;
• computer keyboard lighting;
• to replace fluorescent lamps.

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

Types and parameters of LED strips

LED strip color options

LED strips are produced in different designs according to the type of security. They can be of different brightness and different colors, which is determined by the 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 choose the type of device for specific purposes.

LED strip device

An LED strip is a flexible plastic strip with conductive strips applied to it. Two are located at the edges and are connected to them. The rest connect the 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 pads to which the wires are soldered or connected using connectors.

LEDs can be coated with 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 a double-sided tape. With it, the LEDs are attached to the base.

The most common supply voltage is DC, 12V. There are designs designed for connection to a voltage of 24V and higher, but these are not common designs.

Types of LEDs used

The LEDs and resistors in the tape are used in the SMD series, without leads. LEDs in production are used in various sizes, which determines the marking of the tape - 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, the marking of the SMD 5050 tape 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 to connect.

Important! When you turn on the LED strip in a 220 volt network, it will instantly burn out!

Power supplies are produced in different capacities and shapes. From low-powered, tablet-like chargers to powerful designs in metal case with built-in coolers.

Power supply for LED strips

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

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

If there is no special block available, then you can use:

• Any transformer with an output voltage of 12V. A diode bridge and a smoothing capacitor must be connected to the output.
• The power supply of the computer, both in the computer itself and separately.
• If 3-6 LEDs are needed, then a capacitor can be used to limit the current, as well as a diode bridge and a capacitor that smooths out the glow pulsations. This scheme is used in LED lamps installed instead of incandescent lamps. The capacitance of a capacitor can be calculated using an online calculator.
• Make the board defective energy saving 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 beds with seedlings - several pieces, equal in length to the length of the beds;
• computer keyboard - along the length of the keyboard;
• to replace a fluorescent lamp, several pieces are needed, the length is equal to the length of the lamp.

The brightness of the tape, the size and density of the LEDs is determined based on specific conditions.

The power of the power supply should not be less than the power of the 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 isolate the connection point, a soldering iron with tin and rosin, or a connector for connection.

Expert opinion

Alexey Bartosh

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

Ask an expert

Attention! Do not solder the tape with acid! Acid fumes oxidize and destroy wires, and can also lead to a short circuit.

If the lamp will be used in an aquarium for internal illumination, then a transparent tube and silicone sealant will be needed 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 consists of sticking tape to the base, for example, when backlighting a keyboard located on a pull-out shelf under a table.

In other cases, it is necessary to make a lamp or remake an existing one.

Features and stages of installation work

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

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

Carefully! This tape has high voltage, so all manipulations with it are performed in the disabled state.

What to do if there is no finished LED strip

If there is no ready-made LED strip, then you can make it yourself.

To do this, the required number of LEDs must be connected in series, and a current-limiting resistance must be connected to them. You can assemble such a design 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.

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

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

Opening the base of the lamp immediately showed what the malfunction was. Insulation burned in one of the windings of the ballast device. Obviously 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’s 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 - to install LEDs instead of a fluorescent lamp, and replace the ballast device with an electronic driver, especially since everything was at hand for such a remake.

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 body-tube from heating. Therefore, the linear lamp was not subject to repair, and the diodes were serviceable. In width, the bar with LEDs just fit well into the reflector of the table lamp.

The luminescent U-shaped tube was held in the reflector by a plastic retainer and a plinth. To determine the required length of the LED strip, the lamp with the 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 bar.

The base did not have an additional fastening, and to remove it, it remained only to unsolder the two supply wires. The wires were stranded of sufficient cross section, so I decided to leave them to supply voltage to the LEDs.

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

The cutting line went through right place, the printed tracks connecting the LEDs remained intact.

The existing table lamp reflector fasteners were used to mount the LED bar. The fluorescent lamp was fixed with a plastic bracket screwed to the reflector with a self-tapping screw, and the fixing cover was screwed to the plastic stand.

In the bar between the LEDs, a hole with a diameter of 3 mm was drilled for a self-tapping screw and a sample was made for mounting to the rack. After checking the alignment of the mounting hole with the hole in the short rack, you can proceed to fix the bar with LEDs in the reflector.

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

I used a pre-made PCB with LEDs. But such a board is easy to do with your own hands. Moreover, if you use modern single-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 in each case individually.

The photo clearly shows how the printed circuit board with the LEDs installed on it is fixed in the reflector of the 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 was put on it with a length equal to the height of the right short post.

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. It remains to attach the fixing cover, having previously put a piece of cambric on the protruding stand for its entire length. Thus, sandwiched between two pieces of tubes, the left edge of the bar will also be securely fixed.

Selection and wiring diagram of the driver

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

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

Electrical circuit diagram driver is above. Capacitor C1 with a capacity of 0.8 uF limits the current to 57 mA. R1 and R3 limit the inrush current due to the charge of the capacitors at the moment the driver is connected to the network. Diode bridge VD1-VD4 rectifies the voltage, and the electrolytic capacitor C2 smoothes out the ripple 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 smooths out current surges and at the same time is a fuse. If it is necessary to reduce or increase the supply current of the LEDs, then it will be necessary to reduce or increase the capacitance of the capacitor C1 accordingly. You can increase C1 even without soldering it out of 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, it will increase and the current will also increase.

The constant current, which ensures the optimal brightness of the glow of the LEDs used, is 20 mA. LEDs on printed circuit board three are connected in parallel. Therefore, the current required for their operation according to such a switching circuit 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, the 57 mA current provided by the driver satisfies this requirement.

There were 60 LEDs on the bar. 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 \u003d 2.8 W, which is equivalent to the glow power of an incandescent light bulb of 25 W. The generated illumination of a table lamp is quite sufficient when used as a standby light, night lamp, computer keyboard backlight or reading an e-book.

The weight of the driver is insignificant and therefore I did not fasten it rigidly, I simply grabbed it with a flexible plastic clamp by one of the racks for attaching the halves of the base. The standard table lamp switch was used as a switch. To complete the alteration of the table lamp, it remains only to fasten its base together with three self-tapping screws, and it will be possible to proceed with sea trials.

Table lamp tests 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 allowed not only to restore the table lamp to working capacity at no cost, but also turned the obsolete table lamp into a modern lamp with low energy consumption.

Converting a failed fluorescent lamp into an LED one is a very good idea. Diodes with comparable power consumption shine brighter and last longer. The method of converting a fluorescent lamp into an LED one depends on the type of lamp itself.

Types of luminaire designs for lamps daylight:

• linear;
• compact.

How to convert a linear daylight lamp to LED

If you have a luminaire with a linear housing, it will not be difficult to convert it to the LED version. The easiest way is to use diode tapes. There are even options for connecting to a 220V network without special power drivers. Their peculiarity is that all LEDs are connected in series and the output of one of them will lead to the inoperability of the entire segment.

The wiring diagram is very simple:

Characteristics of the LED strip for 220V:

• Matrix type: SMD 5050;
• number of diodes per running meter: 60 pcs. (60 x 3.5V = 210V);
• load power: 10W;
• light flow: 2100Lm.

According to the brightness of the glow, a meter of such a tape will correspond to an ordinary 100W incandescent light bulb.

Design Benefits:

• Very easy and fast installation and connection.

Design flaws:

• Due to the lack of a smoothing capacitor, the LEDs flicker at a frequency of 100 Hz. According to sanitary standards, such lighting sources cannot be used in residential premises.
• Along the entire length of the tape a large number of contact pads through which 220V voltage passes. To prevent a short circuit, this type of tape is produced only in a sealed case, which makes it difficult to repair if one of the diode arrays burns out.
• The minimum segment length of 50 cm makes it difficult to create compact structures.

The main disadvantage of such tapes is high-frequency flicker. It is practically not perceived by sight, but causes rapid fatigue when performing precise work or reading. The problem is partially solved by installing a high-voltage capacitor in front of the diode bridge at the rate of 60-70 uF x 500V per 10W of tape power.

How to convert a table fluorescent lamp to LED

Remake such a lamp little blood, mounting a 220V tape there will not work. With a minimum segment length of 50 cm, it will not fit into the case, and its design has a very negative attitude to bends. In such a lamp, you can install several strips of diode tapes designed for a voltage of 12V.

The optimal design in this case is as follows:

We use four strips of 25 cm each with 12V wiring. As a result, the brightness will be at the level of 75W incandescent lamps.

Power supply for compact lamp

A meter of tape consumes about 15W and is designed for a current of 1.2A. For such power, buying a 30-watt specialized driver does not make sense. You can use a ready-made factory solution. This miniature power supply with a total power of up to 20W. But the dimensions of 79 x 30 x 24 mm will not allow it to fit in the lamp body.

You can assemble a compact switching power supply with your own hands according to the following scheme. Capacitor 20-30 uF x 400V, Zener diode for 9-12V.

How to convert fluorescent lamps to LED

There are two options for modifying such a light bulb into an LED one:

• use of pieces of diode tape;
• compact lamp with bright LEDs.

Alteration for LED strip

Materials for alteration and connection diagram:

Detailed video instruction for alteration:

For compact desktop solutions, convert the fluorescent lamp to led lamp possible as follows. Unlike the previous version, this design gives a directional light flux and is ideal for illuminating the workplace. Diodes can be used at 0.5 or 1W. Then the final brightness will be 350 Lm or 700 Lm, respectively.

To power the structure, you can use any 12V 2A power supply, if you connect all the LEDs in parallel, or charger from mobile phone at 5V 2A when connected in three parallel lines.

Drivers for powering energy-saving light bulbs for LEDs are not suitable, so feel free to solder the wires going to the base from them, and send the boards for further processing.

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

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

Opening the base of the lamp immediately showed what the malfunction was. Insulation burned in one of the windings of the ballast device. Obviously, due to overheating or poor quality of the 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’s 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 - to install LEDs instead of a fluorescent lamp, and replace the ballast device with an electronic driver, especially since everything was at hand for such a remake.

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 body-tube from heating. Therefore, the linear lamp was not subject to repair, and the diodes were serviceable. In width, the bar with LEDs just fit well into the reflector of the table lamp.

The luminescent U-shaped tube was held in the reflector by a plastic retainer and a plinth. To determine the required length of the LED strip, the lamp with the 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 bar.

The base did not have an additional fastening, and to remove it, it remained only to unsolder the two supply wires. The wires were stranded of sufficient cross section, so I decided to leave them to supply voltage to the LEDs.

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

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

The existing table lamp reflector fasteners were used to mount the LED bar. The fluorescent lamp was fixed with a plastic bracket screwed to the reflector with a self-tapping screw, and the fixing cover was screwed to the plastic stand.

In the bar between the LEDs, a hole with a diameter of 3 mm was drilled for a self-tapping screw and a sample was made for mounting to the rack. After checking the alignment of the mounting hole with the hole in the short rack, you can proceed to fix the bar with LEDs in the reflector.

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

I used a pre-made PCB with LEDs. But such a board is easy to do with your own hands. Moreover, if you use modern single-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 in each case individually.

The photo clearly shows how the printed circuit board with the LEDs installed on it is fixed in the reflector of the 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 was put on it with a length equal to the height of the right short post.

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. It remains to attach the fixing cover, having previously put a piece of cambric on the protruding stand for its entire length. Thus, sandwiched between two pieces of tubes, the left edge of the bar will also be securely fixed.

Selection and wiring diagram of the driver

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

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

The electrical circuit diagram of the driver is shown above. Capacitor C1 with a capacity of 0.8 uF limits the current to 57 mA. R1 and R3 limit the inrush current due to the charge of the capacitors at the moment the driver is connected to the network. The diode bridge VD1-VD4 rectifies the voltage, and the electrolytic capacitor C2 smoothes the ripple 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 smooths out current surges and at the same time is a fuse. If it is necessary to reduce or increase the supply current of the LEDs, then it will be necessary to reduce or increase the capacitance of the capacitor C1 accordingly. You can increase C1 even without soldering it out of 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, it will increase and the current will also increase.

The constant current, which ensures the optimal brightness of the glow of the LEDs used, is 20 mA. The LEDs on the printed circuit board are connected in parallel in three pieces. Therefore, the current required for their operation according to such a switching circuit 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, the 57 mA current provided by the driver satisfies this requirement.

There were 60 LEDs on the bar. 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 \u003d 2.8 W, which is equivalent to the glow power of an incandescent light bulb of 25 W. The generated illumination of a table lamp is quite sufficient when used as a standby light, night lamp, computer keyboard backlight or reading an e-book.

The weight of the driver is insignificant and therefore I did not fasten it rigidly, I simply grabbed it with a flexible plastic clamp by one of the racks for attaching the halves of the base. The standard table lamp switch was used as a switch. To complete the alteration of the table lamp, it remains only to fasten its base together with three self-tapping screws, and it will be possible to proceed with sea trials.

Table lamp tests 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 allowed not only to restore the table lamp to working capacity at no cost, but also turned the obsolete table lamp into a modern lamp with low energy consumption.

Fluorescent lamps are much more economical than incandescent lamps, with the same power, their light output is several times greater. The service life of fluorescent lamps, they write, is 5 years, provided that the number of inclusions does not exceed more than 5 times a day. But, in practice, they nurse much less than 1-1.5, a maximum of 2 years.

In this article, we will consider specific model table fluorescent lamp - Delux - TF-01.

The design of the lamp itself is excellent: it is attached to the table paradise and does not take up space on the table, good design, it has an oblong lampshade, which allows you to conveniently adjust the lighting on the computer desk without illuminating the monitor, for example, but only illuminating the keyboard. Economical, lamp power 11 W. But, in this lamp there is one very significant drawback - the lamps themselves do not burn for a long time, a maximum of six months. When they were still not so expensive (before the crisis in Ukraine), it was tolerable, but when the price increased several times, the expediency of using such a table lamp simply disappeared.

And so the idea arose to convert it to LED. In principle, this is not so difficult to do, LED panels are now sold in any Radio Parts store. But in order to power them, you need a constant voltage of 12 V, which means you need to make a 12 volt power supply.

There are 2 options for manufacturing such a power supply: limit the current with a high-voltage capacitor (400-600 V) to 200-300 mA, then convert the AC voltage to DC - straighten it, and then limit and stabilize it at 12 V. The PSU dimensions in this scenario are minimal and it would fit in the lamp shade housing. According to this scheme, industrial LED lamps are made, which look like an ordinary incandescent light bulb and are screwed into a standard socket. But, the big disadvantage of this scheme is that if some radio component of the power supply fails, the LEDs (panels) instantly break through and also fail (burn out), and they are expensive.

Therefore, it was decided to make a power supply using a step-down transformer according to classical pattern. And by the way, in this case, you can easily adjust the output voltage. This is important so that the LEDs work in the nominal mode, do not overheat, then they will serve for a very long time, and 5, and 10 years, or more.

When altering a table fluorescent lamp - Delux - TF-01, 4 LED panels were used, each with a power of 0.3 W, i.e. in total, a 1.2 W LED lamp was obtained. At the same time, the light is excellent, it instantly lights up, and shines almost for free :)) We throw out all the old electronics from the lamp, or rather we disassemble it for spare parts.

The transformer picked up for 2 W, a bridge, a roll for 12 V (K142EN8B or KR142EN8B, or an imported analogue of a voltage regulator for 12 V - 7812) and a pair of capacitors. True, I had to tinker a little to assemble the LED panels into a block and fix the homemade LED lamp in the lampshade. I cut off a strip of fiberglass and fixed the panels on it with self-tapping screws, and then I attached this strip with the panels to the plastic racks, which I glued to the lampshade body with dichloroethane glue. Krenka, as you can see, put on a small radiator, for reliability. If some jumps appear in the network, the roll and capacitors smooth everything out.

In money, such a lamp cost no more than buying a native fluorescent lamp, but it will serve ten times longer.

Well, like this, you can tinker with the rework once and for 5-7 years, or even longer, not go to the store for new lamps and at the same time reduce electricity consumption by 10 times, compared with fluorescent lamps, and 60 or 75 times - compared to an incandescent lamp. Benefit in person...
I have been using this lamp for 2 years now, I am very satisfied.