Running fire with 10 LEDs. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Running fire with 10 LEDs. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Surge Protectors

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One of the most popular lighting effects implemented in various designs of devices that are used to decorate a Christmas tree is the effect of the so-called running lights. Visually, it is expressed in the fact that in a chain of any light sources, for example, electric light bulbs, in the simplest version, one or a group of sources located one next to the other alternately lights up. At the same time, due to the inertia of our vision, the appearance is created that the light source is moving, "running" along the chain at a certain speed. As light sources in such designs, not only light bulbs, but also, for example, LEDs can be used.

A simple and at the same time reliable device that implements the lighting effect of running lights can be assembled using ordinary LEDs. The proposed design is a conventional switch in which the supply voltage is alternately applied to one of the ten LEDs.

Schematic diagram of the running lights module is shown in the figure.

Running fire with 10 LEDs

This device, which is based on two microcircuits and ten transistors, can be conditionally divided into three functional blocks: a master oscillator, a control unit and an indication circuit. Like most similar designs, the proposed module is made using pulse counters. The master oscillator that generates control pulses is made on the IC2 microcircuit, which is connected according to the unstable multivibrator circuit. In this case, the operating frequency of the master oscillator is determined by the value of the resistance of the resistor R1 and the value of the capacitance of the capacitor C1. When using these elements with the parameters indicated on the circuit diagram, the frequency of the control pulses will be about 15 Hz.

From the output of the master oscillator (output IC2 / 3), control pulses are fed to the control unit, which is based on IC1, which is a pulse counter. At ten outputs of this microcircuit, a sequential formation of a logical unit voltage is provided. Initially, all outputs of the pulse counter have logic zero voltages. In other words, the voltage level at each of the outputs of IC1 (pins IC1 / 1-7.9-11) will be low and insufficient to open the transistor, the base of which is connected to the corresponding output.

When the first control pulse arrives from the master oscillator at the input of the counter CLK (pin IC1 / 14), a logic unit voltage will be generated at the output DO0 (pin IC1 / 3), that is, a voltage of a higher level will be applied to this output. Thus, at one of the outputs of the control unit, a control voltage will appear, which is supplied to the corresponding input of the display unit. In the scheme under consideration, the display unit is made on transistors T1-T10 and LEDs D1-D10.

From the output DO0 (pin IC1 / 3), a high logic level voltage is supplied to the base of the transistor T10 and ensures its unlocking. As a result, through the open junction "collector-emitter" of the transistor T10, the anode of the LD10 LED is connected to the plus of the power source, which leads to the glow of this diode. The arrival of the next control pulse from the master oscillator at the input of the IC1 microcircuit will provide the formation of a logic unit voltage at the DO1 output (pin 1C 1/2). In this case, a low logic level voltage will reappear at the output DO0, the transistor T10 will close, and the LD10 LED will go out. At the same time, the transistor T9 will open, and the diode LD9 will start to glow.

When a continuous sequence of ten control pulses is applied to the input of the counter IC1, a high logic level voltage will be generated in turn at the outputs DO0-DO9, which will ensure successive flashes of the LEDs from LD10 to LD1. If these LEDs are placed one next to the other, then, as already noted, due to the inertia of our vision, the appearance will be created that the luminous diode "runs" along the chain. After the next sequence of ten control pulses is applied to the input of the counter, a repeated cycle of successive flashes of the LEDs will occur. And so it will continue until the power is turned off.

It remains to be added that the use of transistors T1-T10 in this circuit as the keys that control the operation of the LEDs is due to the fact that the current load of the IC1 microcircuit is very insignificant. Therefore, the direct connection of individual LEDs to its outputs can lead to a malfunction of the microcircuit. At the same time, taking into account the fact that only one LED is always lit in the proposed design at a certain point in time, the current through all diodes is limited by one common resistor R2.

All parts of the running lights module are located on a small double-sided printed circuit board measuring 55x35 mm. An image of the printed circuit board is shown in the figure.

Running fire with 10 LEDs

The module is powered from a constant voltage source of 5 V. It can be an ordinary flat battery of the 3336L type or four finger-type cells of 1,5 V each, since reliable operation of this module is also ensured when the supply voltage changes in the range from 4,5 to 6,0 C. As a power source, you can use a conventional mains rectifier for a voltage of 6 V at a current of 200-300 mA. If LEDs with a low operating current (2 mA) are used in this design, and the resistance of the resistor R2 is increased to 1 kOhm, the total power consumption of the device will be significantly reduced. In this case, when powered by a single flat battery, the module will be able to work continuously for several tens of hours.

Imported VS548V transistors can be replaced, for example, with domestic npn-type KT3102VM transistors. LEDs can be replaced with small electric bulbs, rated for 4,5 V, for example. In this case, the resistor R2 is replaced by a jumper.

In the proposed embodiment of the running lights module, all LEDs are placed along one of the sides of the printed circuit board. However, in each case, the location of the LEDs depends only on the artist's imagination. LEDs can be arranged, for example, in the form of a small garland. It can be any letter or initials. In this case, the LEDs are connected to the board using a thin multi-core cable.

Assembled without errors in installation and from serviceable parts, the running lights module almost does not need to be adjusted, with the exception of selecting the operating frequency of the master oscillator, which is determined by the resistance value of the resistor R1 and the capacitance value of the capacitor C1. If desired, the speed of movement of the running lights can be changed by selecting the resistance value of the resistor R1. To increase the speed, the resistance of the resistor R1 should be reduced, and to reduce the speed of movement of the running lights, the resistance of the resistor R1 should be increased.

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