A distinctive feature of the described lighting installation - use instead of conventional incandescent bulbs special pulse. This eliminates the main disadvantage of such devices is high inertia. It can help to get the perfect light accompaniment of musical works, but also solve the problem with the design of the discos, concert halls, living room.
On the pages of "Radio" in the described dynamic light unit (SDU) of various degrees of complexity (e.g., [1, 2]). In all of these devices used incandescent lamps, switchable thyristors or power transistors. However, incandescent lamps have major weaknesses: lag and a limited lifetime which offer strobe SDU. It consists of power supply and three active bandpass filters, and their outputs are connected to three identical control unit flash lamps A1-AZ (Fig. 1).
The power unit is a half-wave rectifier VD6, VD7, connected to the network via a ballast capacitor C12. The rectifier is loaded on the Zener diodes VD4, VD5 and filter capacitors C10, CN, forming a bipolar voltage power operational amplifiers DA1, DA2. The application source with the ballast capacitor significantly reduces the size of the CDS. However, all components have a galvanic connection to the network, what should be remembered when establishing and operation. For this reason, the variable resistors must be fitted with a dielectric handles.
The input signal from the line output of a tape recorder, radio or CD player is supplied to the primary winding of the transformer T1 is designed for galvanic isolation of the signal source from the elements of the CDS. If the input signal is small (less than 0.3 V), the transformer must be increase and ensure the amplitude of the voltage on the secondary winding of about 0.5 V, Then the signal arrives at the inputs of active bandpass filters using variable resistors, which is set to the optimum level.
The filters are made of twin OU DA1, DA2 and borrowed from [1]. The calculation methods have been published in the journal, therefore, is not shown here. In sdes applied filters with the following parameters: the gain at the resonant frequency is 40 dB; q - 10; resonant frequency 680 Hz (upper circuit), 3000 Hz (middle) and 9800 Hz (bottom). Generally, the number of filters can be arbitrary and is limited only by the capacity of the supply. For those wishing to rebuild the resonant frequency will give the following recommendations. Tuning the filter to a different resonant frequency, you must change the capacitance of the capacitors C1, C2 (C4, C5, or C7, C8). In order to still gain at the resonant frequency and quality factor of the filter, should bear the relation: C2=S (similar to C4=C, C7=C). Then, knowing the desired resonant frequency fo, it is possible to determine the capacitance value of one of the filter capacitors. So, for upper circuit filter
C1 =[( 1 /R2 + 1 /R3)/( 10R4)] ^/(6,28 fo),
where the capacitance of the capacitor C1 is the Farad, the frequency fo is in Hertz, resistance of the resistors in ohms. Similarly, calculate the capacitance of the other filters.
Load filters transistors VT1-VT3 common-emitter. At low input signal level or if its frequency falls within the bandwidth of the filter, the amplitude of the filtered signal is insufficient for opening the corresponding transistor. The voltage on the collector is about-8V. If the filter's input signal level is adequate and its frequency falls within the bandwidth of the filter, the transistor opens the amplitude of the negative half-cycle of the filtered signal and its collector observed pulses of positive polarity. In the base circuits of transistors VT1-VT3 series of subtractive Zener diodes VD1-VD3, which increase the deadband. The pulses from the transistors go into blocks A1-AZ.
Consider the work of block A1. Blocks A2 and A3 are similar. When the pulses are absent, charging the storage capacitor C to a voltage of about 300 V through resistors 1R1, 1R2 and diode 1VD1. As SCR 1VS1 is closed, the capacitor C is charged through the resistor 1R5. A pulse of positive polarity supplied from the collector of transistor VT1, SCR opens, discharging the capacitor C to the primary winding of the transformer T. On the secondary winding of an impulse high voltage, which "ignites" pulsed lamp VL1. After the flash lamp is charging the capacitors C, S repeats. Diodes 1VD2, 1VD3 protect the SCR from reverse voltage.
Note that the collectors of the transistors can be formed as separate pulses, and pulse packet. In the latter case, the pulse lamp will turn on only the first pulse in the stack having an amplitude sufficient to open the SCR. As for charging storage capacitors C, C takes time subsequent pulses in a packet will not cause the flash of the flash lamp. SDU is assembled on four separate boards: the three circuit boards are assembled blocks A1-AZ, the fourth - the other elements. This division into a separate fee was quite convenient for the following reasons. To maximize the effect of light support flash lamp must be posted in the space, for example, placing the corners of the room. However use a long wire to connect the flash lamps (one of which is a high voltage) is impractical and dangerous. Much easier to smash the blocks A1-A3. In addition, when they are located on separate circuit boards are very easy to obtain both private and connected strobe lights. For this we need to connect the blocks A1-AZ to a simple digital device that generates a sequence of control pulses.
The main PCB drawing of the CDS is shown in Fig. 2. The holes circled in a semicircle, it is necessary to solder the jumpers connecting the upper and lower traces. Drawing of the PCB blocks A1-AZ shown in Fig.3.
Chips instead of COD you can use the OS series C, K, K, K. Pay particular attention to the corrective circuit. Transistors - any of the series KT361, CT, CT; diodes VD6, VD7, 1VD2-3VD2, 1VD3-3VD3 - series CD, CD alpha index, B-G; Zener diodes VD4, VD5 - DA-DG, VD1-VD3-XA-KS147A; triacs - CUM, CUN. Resistors - MLT, variables - GPA, act or similar. Capacitors C12, S-SS - K73-17, for a voltage not less than 400 V; C10, C11-C50-35, K50-16; S-SS - K50-27 or other, for a voltage exceeding 350; the other is all-ceramic. The transformer T1 is THE one-64 or other small.
Transformers T-ZT wound on a wooden frame with a stem diameter of 10 mm, the diameter of the cheeks 20 mm and the distance between the cheeks is 10 mm. the Magnetic circuit is not used. The first secondary winding is wound wire sew-2 of 0.1. The most quickly and easily can make a transformer with a drill. Specifically, count the number of turns of the secondary winding is not necessary: it is wound almost to the full capacity of the frame. The coil should be two to three times to be impregnated with melted paraffin to prevent high voltage breakdown between turns. After the insulation layer is wound the primary winding containing 10 to 20 turns of wire PEL or sew-2 with a diameter of 0.3...0.6 mm.
It is necessary to pay attention to the type of wires to connect from flash lamps. The wires coming from the secondary winding of the transformers T-T must have good insulation. Also avoid twisting with other wires. The total cable length should not exceed one meter.
In conclusion, some recommendations for the establishment of the CDS. First, you need to install the sliders of variable resistors in the bottom according to the scheme position. Then, submitting the input signal, slowly rotate the engine resistor R1. In the moment of switching on the lamp VL1 be to fix the position of the slider of the variable resistor. Similarly, configure other channels. It should be noted one feature of the CDS. With a significant increase in the level of the input signal, and in case of setting too high a signal level at the input of the at least one filter flash flash lamps will be missing.
To reduce the inrush current when you turn the device to the network in series with the capacitor C12 is advisable to include a resistor 36...47 Ohms. Insulation of the windings of the transformer T1 must be rated for a voltage of 300 V. it is Better to wound yourself, and the windings are securely insulated. Common wire of the device must not be connected to the housing.
Literature
Author: A. Taraz, St. Petersburg; Publication: N. Bolshakov, rf.atnn.ru