Light-dynamic LED lamp - from CFL. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Lighting

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Some compact fluorescent lamps (CFLs) are equipped with an additional matte diffuser, stylized as a classic incandescent lamp. If such a CFL is out of order, its body can be used to assemble a simple LED lighting lamp or make it a light-dynamic or automatic light effects.

Osram's CFL underwent such refinement (Fig. 1). Its peculiarity is that the diffuser can be removed and installed in a special circular groove without much effort.

Rice. 1. Osram CFL

The lamp itself and its electronic filling are carefully removed. First, a built-in network power supply (PSU) with ballast capacitors is made, the circuit of which is shown in Fig. 2.

Rice. 2. Power supply circuit

The capacitance of capacitors C1 and C2 is chosen to provide the PSU output current of 140...150 mA. Resistor R2 limits the inrush current when mains voltage is applied, and through resistor R1, the capacitors are discharged after the lamp is turned off. Thermal fuse F1 protects the PSU from overheating under adverse circumstances. Alternating current rectifies the diode bridge VD1-VD4, and the capacitor C3 smoothes the ripple of the rectified voltage. A parametric voltage regulator with an output voltage of 1 ... 5 V is assembled on the transistor VT12,5 and the zener diode VD13.

Socket XS1 is used to connect the load. This made it possible to quickly change the functional purpose of the lamp by simply replacing modules equipped with a mating connector. In total, three such modules were made: lighting, light-dynamic and for lighting effects. In all cases, LED strips with a nominal voltage of 12 V were used as a light source. In the first case, the number of cells of the LED strip was chosen so that its rated current was slightly greater than the maximum output current of the PSU. Therefore, the PSU output voltage is less than the stabilization voltage, and the LED strip consumes all the current. In other cases, part of the current is consumed by the PSU itself.

Fuse F1 (operating temperature 125 ^оC) was installed in the CFL, it is soldered to the lamp base (XP1). Ballast capacitors must be designed to operate at an alternating voltage of 250 V, they are removed from switching power supplies of computers, and their number may be different, the main thing is that the total capacitance corresponds to that indicated in the diagram. The capacitors are glued together and placed in the base of the lamp (you will have to choose such that they fit into it). Resistors R1 and R2 (MLT or imported) are also located there, and the resistor R2 is composed of two single-watt resistances of 20 ohms connected in parallel, and a thermal fuse Fl. The remaining elements are placed on a printed circuit board made of fiberglass laminated on one side with a thickness of 1 ... 1,5 mm, the drawing of which is shown in Fig. 3. The MLT resistor (R3) is used, the oxide capacitor C3 is imported. Zener diode - any low-power (including two-anode) for a stabilization voltage of 12 ... 12,5 V. We will replace the KT837T transistor with any of the KT818 series in the TO-220 package so that it can dissipate power up to 1,5 W without a heat sink. Socket XS1 - six-pin double-row with a pitch of 2,54 mm (PBD-6). It should be noted that the socket in the PSU and the plug in the modules do not have a key. Therefore, you can insert them without paying attention to its absence, the main thing is that all the contacts of the plug fall into the socket holes. In any case, the positive line of the supply voltage will be on the middle contacts, and the negative line will be on the extreme ones. So you need to connect the power lines and the modules.

Rice. 3. PCB

The power supply board is fixed with glue in the upper part of the base from the CFL (Fig. 4) and connected with wires to the rest of the power supply elements. After checking the performance of the PSU, the base is assembled, and the holes remaining from the CFL cylinder are sealed with sealant or glue (Fig. 5). The XP1 socket does not have to protrude above the sealant layer and can be flush with it.

Rice. 4. PSU board fixed in the upper part of the base from the CFL

Rice. 5. The holes remaining from the CFL cylinder are sealed with sealant or glue

The scheme of the first module (lighting) is shown in fig. 6. It contains an LED strip containing several cells with a total rated current consumption, which was mentioned earlier. A 1,5 mm thick plastic plate measuring 20x55 mm (depending on the dimensions of the diffuser) is glued to an XP1 plug (PLD-6) and an LED strip (Fig. 7). The plug is inserted into the XS1 socket of the PSU and is fixed quite securely in it, a light diffuser is put on top. Since the lamp power does not exceed 1,8 W, its brightness is low, and it can be used in utility rooms or for emergency lighting.

Rice. 6. Scheme of the first module (lighting)

Rice. 7. Plug and LED strip

The second module is designed to create lighting effects, its diagram is shown in fig. 8. On three logic elements DD1.1-DD1.3, a three-phase multivibrator with a pulse repetition rate of a few fractions of a hertz is assembled, which controls transistors VT1-VT3. Pulses appear at the outputs of logic elements one after another with a time delay. Therefore, crystals of different colors are switched on alternately. In order to increase the brightness relatively smoothly when turned on, capacitors C2, C4 and C6 are installed. The pulse repetition rate depends on the time constant of the circuits R1C1, R3C3 and R5C5. By changing the values ​​of these elements over a wide range, it is possible to change the pulse repetition rate.

Rice. 8. Scheme of the second module (click to enlarge)

All elements of the second module are installed on a board made of fiberglass with a thickness of 1 ... 1,5 mm, foiled on one side, its drawing is shown in Fig. 9. Resistors R1-4, C2-23 are used, oxide capacitors are imported low-profile so that the board can freely pass through the neck of the diffuser. PN2222 transistors can be replaced with domestic KT503 series. The view of the mounted board is shown in fig. 10.

Rice. 9. Drawing of the board of the second module

Rice. 10. View of the mounted board

This module uses a tape with a nominal voltage of 12 V, containing three cells, each of which has three tricolor LEDs. The tape is wrapped around the board and secured along its edge with glue. The total current consumed by crystals of the same color is 45 ... 55 mA. Since not all LEDs are turned on at the same time, the total tape current does not exceed 150 mA, i.e. the maximum output current of the PSU.

If the glow of this lamp based on a three-phase multivibrator may seem monotonous, the module circuit can be changed by turning the three-phase multivibrator into three independent generators. To do this, eliminate the connection between the logical elements by cutting the corresponding printed conductors. On fig. 8 they are shown with red crosses, in fig. 9 - thinner lines. Then, with pieces of insulated wire, the connections shown in fig. 8 dashed lines.

The third module is light-dynamic. It has a light source - also a piece of LED strip with three-color LEDs. The color of the glow of the lamp with this module will change in time with music or other sounds, as well as with their spectral composition. The module diagram is shown in fig. eleven . It consists of a microphone amplifier on the op-amp DA11 and three active band-pass filters on the op-amp DA1.1-DA1.2. A filter with a center frequency of about 1.4 kHz is assembled on the op-amp DA1.2, on the op-amp DA3 - with a frequency of about 1 kHz, on the op-amp DA3 - with a frequency of about 1 Hz. Gain of active filters - 1.4...150 dB. The signal from the output of the filters is fed respectively to the transistors VT20-VT25. The base transistor circuits include C1R3, C9R11, and C10R12 auto-bias circuits. Current flows through the resistors R11-R13 into the bases of the transistors, so the transistors open slightly and a small current flows through the LEDs, causing them to glow weakly. When a signal appears at the output of the filters, the current begins to flow through the capacitors C11-C13, the transistors open more and the LEDs begin to shine brighter. Capacitors do not have time to quickly discharge through "their" resistors, so a voltage appears on them, which closes the transistors. The greater the signal voltage, the greater the closing voltage. This compresses the dynamic range of the output signals to support dynamic LED brightness changes.

Rice. 11. Scheme of the third module (click to enlarge)

The drawing of the board of the third module is shown in fig. 12, and the view of the mounted board - in fig. 13. Used ceramic imported or domestic (K10-17) capacitors, other elements - as in the previous module. The LED strip is wrapped around the board (Fig. 14) and secured with glue. In order for the module to work properly, acoustic holes will have to be made in the diffuser.

Rice. 12. Drawing of the board of the third module

Rice. 13. View of the mounted board

Rice. 14. LED strip

The adjustment begins with the selection of the resistor R1 (and, if necessary, R3). With its help, a constant voltage of 1.1 ... 5 V is set at the output of the op-amp DA6. The same voltage should be at the output of the remaining op-amps. A selection of resistor R4 sets the desired gain of the microphone amplifier. Resistors R11-R13 set the initial current of the transistors. It is necessary to adjust and check the performance of all modules only in conjunction with a laboratory PSU with a voltage of 12 V, since the PSU of the lamp has a galvanic connection with the network!

It should be noted that the proposed design of the modified lamp allows you to connect to it modules for various purposes, for example, with a motion sensor, etc.

Author: I. Nechaev

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