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 a switching 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 power a 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. 
I installed the LED using thermal paste on a metal lampshade of an old table lamp. 
I installed the power board and diode bridge into the body of a table lamp. 
When working for about an hour, the LED temperature is 40 degrees. 
To the eye, the illumination is like that of a 100-watt incandescent lamp. 
Very often, the cause of breakdown of an electrical appliance is a faulty battery. As a result, repairs or the purchase of new equipment are required. But you can avoid high costs by making a power supply from an energy-saving lamp yourself. All the necessary parts can be taken from a regular fluorescent lamp, the cost of which is low.
Each energy-saving light bulb contains a small circuit that prevents flickering when turned on, and also helps to gradually warm up the device's coils. Its name is electronic ballast. It is with the help of it that gas can emit a glow (frequency 30−100 kHz, and sometimes 105 kHz).
Due to the fact that the device can have such high frequencies, the energy consumption coefficient increases to unity, and this, in turn, makes energy-saving lamps economically beneficial.
A significant advantage of such devices is the absence of any noise during operation, as well as the absence of an electromagnetic field, which negatively affects the human body.
An important role in the ballast circuit of an energy-saving lamp electronic throttle plays. It is he who determines whether the device will light up immediately with full force or warm up gradually over several minutes. It is worth noting that the manufacturer never indicates the heating time on the packaging. This can only be checked during operation of the device.
Those ballast circuits that perform the function of voltage conversion (and most of them) are assembled on semiconductor transistors. In expensive devices, the circuit is more complex than in cheap light bulbs.
From a burnt-out energy-saving lamp you can make blanks for a future switching power supply. You can also take a working device for this.
As part of a compact fluorescent light bulb (CFL) the following elements are available:
When making a power supply from an energy-saving lamp with your own hands using expensive housekeepers, it is enough to supplement the source with some details. You can also use a driver for LEDs, which are often installed in flashlights, as the basis for the future block.
It is important to note that to implement a UPS, it is not recommended to use a circuit with an electrolytic capacitor. This is due to the fact that it will not last long in the device as a power supply. Also, electronic ballasts, which contain special small boards, are not suitable for this purpose.
A UPS is an inverter system in which the input voltage is rectified and then converted into pulses. The main feature of the UPS is a significant increase in the frequency of the current transmitted to the transformer. It is also worth noting the small dimensions of such a device. Another advantage is that the power supply does not have any energy losses during operation, unlike linear ones, which lose a significant part during conversion to the transformer.
The principle of operation of a switching power supply from an energy-saving lamp is as follows:
As a rule, modern circuits use MOSFET transistors. Their main feature is their very fast switching speed. Accordingly, high-speed diodes should be used in such ballasts. They are located in the output rectifier.
When making UPSs, it is better to use Schottky diodes, since they lose the least amount of energy when operating at high frequencies (unlike silicon diodes, in which this figure is much higher).
If the output voltage is very low, then a transistor can perform the rectifier function. Alternatively, you can use a throttle instead. Such simple current converters are found in circuits of 20 W energy-saving lamps.
Most often, during the manufacture of a switching power supply, it is necessary to slightly change the structure of the inductor if a two-transistor circuit is used for this purpose. Of course, some elements in the device will need to be removed.
If a power supply is being manufactured that will have a power of 3.7-20 Watts, then the transformer is not the main component. Instead, it is best to make several turns of wire, which are attached to the magnetic circuit. To do this, it is not necessary to get rid of the old winding; they can be done on top.
It is recommended for this purpose to use MGTF brand wire with fluoroplastic insulation. A small amount will be needed. Despite this, the winding will be completely covered, since most of it is allocated to insulation. Because of this, such devices have low power ratings. To increase it, you need to use an AC transformer.
The main advantage of making a power supply with your own hands is that it is possible to adapt to the transformer performance. In addition, there is no need for a feedback circuit, which is most often an integral part in the operation of the device. Even if some mistakes were made during assembly, most often such a block will work.
In order to make a transformer with your own hands, you will need to have a choke, inter-winding insulation, and a winding. The latter is best made from varnished copper wire. It should be remembered that the choke will operate under voltage.
The winding must be carefully insulated even when it has a factory-made special protective film made of synthetic material. As insulation, you can use either electrical cardboard or ordinary paper tape, the thickness of which should be at least 0.1 mm. Only after the insulation has been made can copper wire be wound over it.
As for the winding, it is best to choose the wire as thick as possible, but the number of required turns can be selected based on the required performance indicators of the future device.
Thus, it is possible to make a UPS that will have a power of more than 20 W.
To prevent saturation of the magnetic circuit in the pulse unit, it is necessary to use only a full-wave output rectifier. In the event that the transformer must step down the voltage, it is recommended to use a zero-point circuit. To implement such a circuit, you need to have two absolutely identical secondary windings. You can make them yourself.
It should be taken into account that a diode bridge type rectifier is not suitable for this purpose. This is due to the fact that a significant amount of power will be lost during transmission, and the electrical voltage value will be minimal (less than 12V). But if you make a rectifier from special pulse diodes, then the cost of such a device will be much more expensive.
After the power supply is assembled, you need to check its operation at maximum power. This is necessary in order to measure the heating temperature of the transformer and transistor, the values of which should not exceed 65 and 40 degrees, respectively. To avoid overheating of these elements, it is enough to increase the cross-section of the winding wire. It also often helps to change the power of the magnetic circuit upward (the ESR is taken into account). If the choke was taken from the ballast of an LED lamp, it will not be possible to increase the cross-section. The only option is to control the load on the device.
to the horndriver
To install a switching power supply into a screwdriver, the power tool will need to be disassembled. As a rule, its outer part consists of two elements. The next step is to find the wires that connect the engine to the battery. They are the ones that need to be connected to the power supply (homemade) using heat shrink tubing. You can also solder the wires. It is strongly not recommended to twist them.
To bring the cable out, you will need to make a hole in the screwdriver body. It is also recommended to install a fuse that will protect the wire from damage at the base. To do this, you can make a special clip from thin aluminum wire.
Thus, converting the ballast circuit into a pulse unit will help replace a damaged battery in a screwdriver. In addition, if we take into account all the nuances from the field of economics during manufacturing, then we can say that making a UPS with your own hands is profitable.
Modern power tools are popular because they allow you not to be tied to an electrical outlet during operation, which expands the possibilities of their use, even in field conditions. The presence of a rechargeable battery significantly limits the duration of active work, so screwdrivers and drills require constant access to a power source. Unfortunately, in modern tools (usually made in China), the power supply battery has little reliability and often quickly fails, so craftsmen have to make do with improvised materials in order not only to assemble a switching power supply, but also to save money on it.
An example of such a hand-made product is a switching power supply (UPS) for an 18 V cordless screwdriver, assembled from the elements of a non-working energy-saving lamp, which can be useful even after its “death”.
The structure of an energy-saving lamp
To understand how an energy-saving lamp can be useful, let’s consider its structure.
The design of the lamp consists of the following components:
Two spirals (electrodes) are connected to the lamp bulb, which, under the influence of current, become heated and emit electrons from their surface. As a result of the interaction of electrons with mercury vapor, a smoldering charge appears in the flask, which “gives birth” to UV radiation. By influencing the phosphor, ultraviolet light “makes” the lamp glow. The color temperature of the housekeeper is determined by the chemical composition of the phosphor.
An energy-saving lamp can fail in two cases:
If the bulb is destroyed, the lamp can simply be thrown away, and if the electronic ballast breaks, it can be repaired or used for its own purposes, for example, used to make a UPS by adding an isolation transformer and a rectifier to the circuit.
Complete set of electronic ballast for energy-saving lamps
Most EB lamps are high-frequency voltage converters assembled on semiconductor triodes (transistors).
More expensive devices are equipped with a complex electronic circuit, while cheaper ones are equipped with a simplified one.
The electronic ballast is “equipped” with the following electrical elements:
The figure below shows the composition of the lamp's electronic ballast with a functional description of each element.
Functional Description
Some EB circuits of energy-saving lamps allow you to almost completely replace the circuit of a homemade pulsed source, adding several elements to it and making minor changes.
Some converter circuits operate on electrolytic capacitors or contain a specialized microcircuit. It is better not to use such electronic circuits, because they are often the source of failures of many electronic devices.
Below is one of the common electrical circuits of the lamp, supplemented by an A-A’ jumper that replaces the missing parts and lamp, a pulse transformer and a rectifier. Schematic elements highlighted in red can be deleted.
Electrical circuit of a 25 W “housekeeper”
As a result of some changes and necessary additions, as can be seen from the diagram below, it is possible to assemble a switching power supply, where the added elements are highlighted in red.
Final electrical diagram of the UPS
The “second” life of the “housekeeper” is often used by modern radio amateurs. After all, their hand-made products often require a power transformer, the availability of which poses certain difficulties, starting with its purchase and ending with the consumption of a large amount of wire for winding and the overall dimensions of the final product. Therefore, craftsmen have gotten used to replacing the transformer with a switching power supply. Moreover, if you use the electronic ballast of a faulty lighting device for these purposes, this will significantly save money, especially for a transformer with a power of more than 100 W.
A low-power switching power supply can be built by secondary winding the frame of an existing inductor. To obtain a higher power power supply, an additional transformer will be required. A 100 W switching power supply can be made on the basis of 20-30 W EB lamps, the circuit of which will have to be slightly modified by adding a rectifying diode bridge VD1-VD4 and increasing the cross-section of the inductor winding L0.
Homemade transformer power supply
If it is not possible to increase the gain of the transistors, you will have to increase their base current by changing the values of resistors R5-R6 to smaller ones. In addition, you will have to increase the power parameters of the base and emitter circuit resistors.
At a low generation frequency, you will have to replace capacitors C4, C6 with elements with a higher capacity.
power unit
A low-power switching power supply with power parameters of 3.7-20 W does not require the use of a pulse transformer. To do this, it will be enough to increase the number of turns of the magnetic circuit on the existing inductor. The new winding can be wound over the old one. To do this, it is recommended to use MGTF wire with fluoroplastic insulation, which will fill the lumen of the magnetic circuit, which will not require a large amount of material and will provide the necessary power of the device.
To increase the power of the UPS, you will have to use a transformer, which can also be built on the basis of an existing EB choke. Only for this purpose it is recommended to use varnished winding copper wire, having previously wound a protective film on the original inductor winding to avoid breakdown. The optimal number of turns of the secondary winding is usually selected experimentally.
To connect a switching power supply assembled on the basis of an electronic ballast, you need to disassemble the screwdriver by removing all fasteners. Using soldering or heat-shrinkable tubing, we connect the device’s motor wires to the UPS output. Connecting wires by twisting is not a desirable contact, so we forget about it as unreliable. First, we drill a hole in the tool body through which we will run the wires. To prevent accidental tearing out, the wire must be crimped with an aluminum clip at the very hole in the inner surface of the power tool body. The size of the clip, which exceeds the diameter of the hole, will prevent the wire from being mechanically damaged and falling out of the housing.
Screwdriver
As you can see, even after working out, an energy-saving lamp can last a long time, bringing benefits. On its basis, you can assemble a low-power pulse power supply unit up to 20 W, which will perfectly replace an 18 V power tool battery or any other charger. To do this, you can use the elements of the electronic ballast of an energy-saving lamp and the technology described above, which is what craftsmen use, most often to repair a faulty battery or save on the purchase of a new power source.
Homemade solar collectors for swimming pools, installation process
One of the easiest ways to make a switching power supply with your own hands from “improvised means” is to convert an energy-saving lamp into such a power supply. Since the main reason for the failure of compact fluorescent lamps is the burnout of one of the filaments of the bulb, almost all of them can be converted into a switching power supply with the required voltage. In this particular case, I converted the electronic ballast circuit of a 15-watt light bulb into a 12-volt, 1-amp switching power supply. Such a modification does not require enormous effort and a large number of parts, because the estimated loaded power is less than the power of the most energy-saving light bulb. 
Each lamp manufacturer has its own sets of parts with certain ratings in the circuits of manufactured electronic ballasts, but all circuits are standard. Therefore, in my diagram I did not show the entire diagram of the lamp, but indicated only its typical beginning and the piping of the lamp bulb. The electronic ballast circuit is drawn in black and red. The bulb and capacitor connected to two filaments are highlighted in red. They should be removed. The elements that need to be added are indicated in green on the diagram. Capacitor C1 - should be replaced with a larger capacity, for example, 10-20u 400v. 
A fuse and input filter are added to the left side of the circuit. L2 is made on a ring from the motherboard, has two windings of 15 turns of twisted pair wire Ø – 0.5 mm. The ring has an outer diameter of 16mm, an inner diameter of 8.5mm, and a width of 6.3mm. Choke L3 has 10 turns Ø – 1 mm, made on a ring from the transformer of another energy-saving lamp. You should choose a lamp with a larger emptiness of the Tr1 choke window, since it will need to be converted into a transformer. I managed to wind 26 turns Ø – 0.5 mm on each half of the secondary winding. This type of winding requires perfectly symmetrical winding halves. To achieve this, I recommend winding the secondary winding in two wires at once, each of which will serve as a symmetrical half of the other. I left the transistors without radiators, because... the expected consumption of the circuit is less than the power consumed by the lamp. As a test, 5 meters of RGB LED strip with a consumption of 12v 1A was connected for maximum illumination for 2 hours.
Energy-saving lamps are gaining more and more popularity, allowing you to save energy; they also have an even white light; there are also warm light lamps, similar in color to incandescent lamps. But unfortunately, energy-saving lamps also do not last forever, some people simply throw them away, while others... make useful homemade products out of them.
In this article we will look at how to make a simple switching power supply from an energy-saving lamp. In most cases, in an energy-saving lamp, the filaments located in the bulb fail, but the electronic part remains intact.
We take a faulty energy-saving lamp. And using a screwdriver we pry off the two halves of the body. We follow the contour and alternately bend one half from the other.
Approximately all energy-saving lamps are made according to this scheme:
In order to make a switching power supply, we will change it to this form:
First, we remove all the pins, two capacitors and diodes (if any), as you can see in the photo, I didn’t have them.
We remove the pulse inductor, there are two options here, the first is that the secondary winding is wound into the free space of the inductor and it is installed back on the board. In this case, it will not be possible to obtain more power. The second method is to wind a pulse transformer, for example, on a ferrite ring. When installing radiators on transistors, you can get a power of 100W or more.
I didn’t need a lot of power, the goal was to power a meter of white LED strip to make something like a kitchen night light :). I also chose about 8-10 Volts for the supply voltage, so that the tape would not glow very brightly; in this mode of operation it would last much longer.
The throttle is removed, we disassemble it, this is quite easy to do, unwind the yellow synthetic film, and take out the two halves of the ferrite. Before winding the secondary winding, you need to make insulation, simply wrap electrical cardboard, plain paper, or plumbing tape around the primary winding. Next we wind a few turns.
We also make insulation and bring out the edges of the winding.
We assemble the transformer in the reverse order; I used “Second” glue.
We install the transformer on the board. We connect P1 and P4 with a jumper (see the diagram).
For testing, I connected the rest of the coil of LED strip, having first rectified the voltage using a diode and a capacitor. The output voltage was 9 Volts.
The switching power supply from the energy-saving lamp is ready, working, nothing gets hot on the board.
