LED lights do-it-yourself
Gradually, lighting devices are switching to LED lamps. It did not happen immediately, there was a protracted transitional period with the use of so-called housekeepers - compact gas-discharge light bulbs with a built-in power supply unit (driver) and a standard cartridge E27 or E14.These lamps are widely used today, because their cost is not so “biting” compared to LED light sources. With a good balance between price and economy (the difference in price with conventional incandescent bulbs with time pays off by saving electricity), gas-discharge light sources have several disadvantages:This is a high-quality (and relatively inexpensive) lamp with a brightness of 1000 Lm (equivalent to a 100 watt incandescent lamp), and a power consumption of 13 watts.I have such LED light sources that work for many years, they shine with a pleasant warm light (temperature 2700 K), and no degradation of brightness is observed with time. But for a powerful light, serious cooling is required. Therefore, the body of this lamp on 2/3 consists of a radiator. It is plastic, does not spoil the appearance, and is quite effective. The main disadvantage of the design is that the real light source is the hemisphere at the top of the lamp. This makes it difficult to choose a lamp - such a lamp will not look harmonious in every chandelier. There is only one way out - to buy ready-made LED lamps, the configuration of which was originally designed for specific light sources. The key word is to buy. And where to put your favorite floor lamps, chandeliers and other lamps in the apartment?The characteristics are as follows:As power supplies (more precisely, current sources), I decided to use a proven circuit with a damping (ballast) capacitor. The advantages of such a driver - extreme low cost, and minimal energy consumption. Since there is no PWM controller,or linear current stabilizer - the excess energy does not escape into the atmosphere: in this scheme there are no elements with a heat dissipating radiator. The disadvantage is the lack of current stabilization. That is, with an unstable power supply voltage, the brightness of the glow will change. My outlet has exactly 220 (+/- 2 volts), so this scheme is just right. The element base is also not expensive.After a neat (on the street!) removing a flask with mercury vapors, there remains an excellent preparation for creativity. >
- Lifetime is lower than that of incandescent bulbs.
- High Frequency interference from the power supply.
- Lamps do not like frequent switching on and off.
- A gradual decrease in brightness.
- Effect on nearby surfaces: a dark spot appears on the ceiling surface (above the lamp).
- Anyway, have a flask with some mercury in the house somehow you don't really want it. A great alternative is LED lamps.The list of advantages is weighty:
- Excellent economy (up to 10 times in comparison with incandescent lamps).
- Huge service life.
- Perfect and safe power supplies (drivers).
- Absolutely independent of the number of starts.
- During normal cooling, almost the entire period of operation does not lose brightness.
- Full mechanical safety (even if you break the decorative lens, no harmful substances will get into the room).
- The directivity of the luminous flux imposes in High requirements for the design of the diffuser.
- Still, they are expensive (we are talking about high-quality brands, middle-class unnamed products are quite affordable).
Therefore, it was decided to design LED lamps independentlyThe main criterion is cost minimization. There are two main directions when developing LED light sources: 1. The use of low-power (up to 0.5 W) LEDs. They require a lot, you can configure any form. No need for a powerful radiator (little warm).A significant drawback is a more laborious assembly. 2. Use of powerful (1 W - 5 W) LED elements. Efficiency is high, labor costs are several times less. But the point radiation requires the selection of a scatterer, and for the implementation of the project we need good radiators. For experimental designs, I chose the first option. The most inexpensive "raw materials": 5 mm LEDs with a dispersion of 120 ° in a transparent case. They are called "straw hat."
- direct current = 20 mA (0.02 A)
- voltage drop across 1 diode = 3.2-3.4 volts
- color - warm white
- diode bridges of the KTS405A series (you can use any diodes, even Schottky)
- film capacitors with a voltage of 630 volts (with a margin)
- 1-2 watt resistors
- 47 mF electrolytic capacitors at 400 volts (you can take a larger capacity, but this goes beyond the economy)
- little things like a breadboard and fuses, usually in the arsenal of any radio amateur
The basis of the basics is the calculation and operation of the current driver with the damping capacitorA typical diagram is shown in the illustration:
How the circuit works:Resistor R1 limits the current surge when power is applied until the circuit stabilizes (about 1 second). The value is from 50 to 150 ohms. Power 2 W. Resistor R2 provides the operation of the ballast capacitor. First, it discharges it when the power is turned off. At least to ensure that you do not shake the current when you unscrew the bulb. The second task is to prevent current surge in the case when the polarity of the charged capacitor and the first half-wave 220 volt do not coincide. Actually, the quenching capacitor C1 is the basis of the circuit. It is a kind of current filter. Selecting the capacity, you can set any current in the circuit. For our diodes, it should not exceed 20 mA at peak mains voltage. Next, the diode bridge is working (after all, the LEDs are elements with polarity). Electrolytic capacitor C2 is needed to prevent flickering of the lamp. LEDs do not have inertia when on-off. Therefore, the eye will see flicker with a frequency of 50 Hz.By the way, this cheap Chinese lamps are sinning. Check the quality of the capacitor with any digital camera, even a smartphone. Looking at the burning diodes through the digital matrix, you can see the blinking, indistinguishable to the human eye. In addition, this electrolyte gives an unexpected bonus: the lights are turned off not immediately, but with a noble slow attenuation, until the capacity is discharged. Calculation of the quenching capacitor is as follows: I = 200 * C * (1.41 * U network - U led) I - received circuit current in amperes 200 is a constant (network frequency 50Hz * 4) 1.41 - constant С - capacitor C1 capacitor (quenching) in farads U network - the expected voltage of the network (ideally - 22 0 volts) U led - the total voltage drop across the LEDs (in our case, 3.3 volts multiplied by the number of LED elements) Selecting the number of LEDs (with a known voltage drop) and the capacity of the quenching capacitor, the required current. It should not be higher than the specified in the characteristics of LEDs. It is the current you adjust the brightness of the glow, and inversely proportional to the lifetime of the LEDs. For convenience, you can create a formula in Exel. The scheme has been checked several times, the first copy was assembled almost 3 years ago, it works in a lamp in the kitchen, there were no failures. We proceed to the practical implementation of projects. The number of LED elements and the capacitance of the capacitor in separate circuits is of no use: individual designs for each luminaire. Calculated strictly by the formula. The above scheme for 60 LEDs with a 68 microfarad capacitor is not just an example, but a real calculation for the current in the circuit 15 mA (to extend the life of the luminaires).
LED lamp in a carob chandelierThe gutted cartridge from the housekeeper is used as a housing for the circuit and supporting structure. In this project, I did not use a model board, assembled a driver for a round of PVC with a thickness of 1 mm. It turned out just in size. Two capacitors - due to capacity selection: there was no necessary number of microfarads in one element.
LED lamp in a flat ceiling light in the kitchenThe ideal donor for a similar project. All LEDs will be located in the same plane.
LED lamp for a bathroomToo easily implemented project. Extract the contents of the lamp, set the matrix to 30 LEDs, and the corresponding driver.
Table lampThe deodorant cap is used as the case.
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