Flashing beacons are used in electronic home security systems and on cars as indication, signaling and warning devices. Moreover, their appearance and “filling” are often not at all different from flashing lights (special signals) of emergency and operational services.
There are classic beacons on sale, but their internal “filling” is striking in its anachronism: they are made on the basis of powerful lamps with a rotating cartridge (a classic of the genre) or lamps such as IFK-120, IFKM-120 with a stroboscopic device that provides flashes at regular intervals ( pulse beacons). Meanwhile, this is the 21st century, when there is a triumphal march of very bright (powerful in terms of luminous flux) LEDs.
One of the fundamental points in favor of replacing incandescent and halogen lamps with LEDs, in particular in flashing beacons, is the longer service life (uptime) and lower cost of the latter.
The LED crystal is practically indestructible, so the service life of the device mainly determines the durability of the optical element. The vast majority of manufacturers use various combinations of epoxy resins for its production, of course, with varying degrees of purification. In particular, because of this, LEDs have a limited resource, after which they become cloudy.
Various manufacturers (we won’t advertise them for free) claim a lifespan of their LEDs from 20 to 100 thousand (!) hours. I have a hard time believing the last figure, because the LED should work continuously for 12 years. During this time, even the paper on which the article is printed will turn yellow.
However, in any case, compared to the resource of traditional incandescent lamps (less than 1000 hours) and gas-discharge lamps (up to 5000 hours), LEDs are several orders of magnitude more durable. It is quite obvious that the key to a long resource is to ensure favorable thermal conditions and stable power supply to the LEDs.
The predominance of LEDs with a powerful luminous flux of 20 - 100 lm (lumens) in the latest industrial electronic devices, in which they work instead of incandescent lamps, gives radio amateurs the basis to use such LEDs in their designs. Thus, I bring the reader to the idea of the possibility of replacing various lamps in emergency and special beacons with powerful LEDs. In this case, the current consumption of the device from the power source will decrease and will depend mainly on the LED used. For use in a car (as a special signal, emergency warning light, and even a “warning triangle” on the roads), current consumption is not important, since the car’s battery has a fairly large energy capacity (55 or more Ah or more). If the beacon is powered from an autonomous source, then the current consumption of the equipment installed inside will be of no small importance. By the way, a car battery without recharging can be discharged if the beacon is used for a long time.
So, for example, a “classic” beacon for operational and emergency services (blue, red, orange, respectively), when powered by a 12 V DC source, consumes a current of more than 2.2 A, which is the sum of that consumed by the electric motor (rotating the socket) and the lamp itself. When a flashing pulse beacon is operating, the current consumption is reduced to 0.9 A. If, instead of a pulse circuit, you assemble an LED circuit (more on this below), the consumption current will be reduced to 300 mA (depending on the power of the LEDs used). Savings in parts costs are also noticeable.
Of course, the question of the strength of light (or, better said, its intensity) from certain flashing devices has not been studied, since the author did not have and does not have special equipment (lux meter) for such a test. But due to the innovative solutions proposed below, this issue becomes secondary. After all, even relatively weak light pulses (in particular from LEDs) passed through the prism of the non-uniform glass of the beacon cap at night are more than sufficient for the beacon to be noticed several hundred meters away. That's the point of long-range warning, isn't it?
Now let’s look at the electrical circuit of the “lamp substitute” of the flashing light (Fig. 1).
This multivibrator electrical circuit can rightfully be called simple and accessible. The device is developed on the basis of the popular integrated timer KR1006VI1, containing two precision comparators that provide a voltage comparison error of no worse than ±1%. The timer has been repeatedly used by radio amateurs to build such popular circuits and devices as time relays, multivibrators, converters, alarms, voltage comparison devices and others.
The device, in addition to the integrated timer DA1 (multifunctional microcircuit KR1006VI1), also includes a time-setting oxide capacitor C1 and a voltage divider R1R2. C3 of the output of the DA1 microcircuit (current up to 250 mA), control pulses are sent to the LEDs HL1-HL3.
How the device works
The beacon is turned on using switch SB1. The operating principle of a multivibrator is described in detail in the literature.
At the first moment, there is a high voltage level at pin 3 of the DA1 microcircuit - and the LEDs light up. The oxide capacitor C1 begins to charge through the circuit R1R2.
After about one second (the time depends on the resistance of the voltage divider R1R2 and the capacitance of capacitor C1, the voltage on the plates of this capacitor reaches the value necessary to trigger one of the comparators in the single housing of the DA1 microcircuit. In this case, the voltage at pin 3 of the DA1 microcircuit is set equal to zero - and the LEDs go out. This continues cyclically as long as the device is supplied with power.
In addition to those indicated in the diagram, I recommend using high-power HPWS-T400 or similar LEDs with a current consumption of up to 80 mA as HL1-HL3. You can use only one LED from the series LXHL-DL-01, LXHL-FL1C, LXYL-PL-01, LXHL-ML1D, LXHL-PH01,
LXHL-MH1D manufactured by Lumileds Lighting (all orange and red-orange glow colors).
The supply voltage of the device can be increased to 14.5 V, then it can be connected to the on-board vehicle network even when the engine (or rather, the generator) is running.
Design Features
A board with three LEDs is installed in the housing of the flashing light instead of the “heavy” standard design (lamp with a rotating socket and electric motor).
In order for the output stage to have even more power, you will need to install a current amplifier on transistor VT1 at point A (Fig. 1), as shown in Fig. 2.
After such modification, you can use three parallel-connected LEDs of the types LXHL-PL09, LXHL-LL3C (1400 mA),
UE-HR803RO (700 mA), LY-W57B (400 mA) - all orange. In this case, the total current consumption will increase accordingly.
Option with flash lamp
Those who have preserved parts of cameras with a built-in flash can go the other way. To do this, the old flash lamp is dismantled and connected to the circuit as shown in Figure 3. Using the presented converter, also connected to point A (Figure 1), pulses with an amplitude of 200 V are received at the output of the device with a low supply voltage. Supply voltage in this case it is definitely increased to 12 V.
LED beacon circuit on timer KR1006VI1 |
This design, or rather its diagram, can be called simple and accessible. The device operates on the basis of the KR1006VI1 timer, which has two precision comparators. In addition, the device includes a timing oxide capacitor C1, a voltage divider across resistances R1 and R2. From the third output of the DA1 chip, control pulses follow to the LEDs HL1-HL3.
The circuit is turned on using toggle switch SB1. At the initial moment of time, the output of the timer has a high voltage level and the LEDs light up. Capacity C1 begins to charge through the circuit R1 R2. After one second, the time can be adjusted by resistances R1 R2 and capacitor C1, the voltage on the capacitor plates reaches the response value of one of the comparators. In this case, the voltage at pin three DA1 will be zero, the LEDs will go out. This continues from cycle to cycle as long as voltage is applied to the amateur radio structure.
It is recommended to use high-power LEDs HPWS-T400 or similar ones with a current consumption of no higher than 80 mA in the design. You can also use one LED, for example LXHL-DL-01, LXHL-FL1C, LXYL-PL-01, LXHL-ML1D, LXHL-PH01.
Finding various objects or, for example, pets in the dark will become easier if you attach our amateur radio development to them, which will automatically turn on when darkness falls and begin to emit a light signal.
This is a regular asymmetrical multivibrator based on bipolar transistors of different conductivity VT2, VT3, which generates short pulses with an interval of a couple of seconds. The light source is a powerful LED HL1, the light sensor is a phototransistor.
A phototransistor with resistances R1, R2 forms a voltage divider in the base circuit of transistor VT2. During daylight hours, the voltage at the emitter junction of transistor VT2 is low, and it is locked together with its colleague VT3. With the onset of darkness, the transistors begin to operate in the mode of generating pulses from which the LED flashes
One of the simplest circuits in amateur radio electronics is an LED flasher on a single transistor. Its production can be done by any beginner who has a minimum soldering kit and half an hour of time.
Although the circuit under consideration is simple, it allows you to clearly see the avalanche breakdown of the transistor, as well as the operation of the electrolytic capacitor. Including, by selecting the capacitance, you can easily change the blinking frequency of the LED. You can also experiment with the input voltage (in small ranges), which also affects the operation of the product.
Design and principle of operation
The flasher consists of the following elements:- power supply;
- resistance;
- capacitor;
- transistor;
- Light-emitting diode.
The capacitor is located in the circuit before the closed transistor, therefore it accumulates electrical energy. This happens until the voltage at its terminals reaches a value sufficient to ensure the so-called avalanche breakdown.
In the second phase of the cycle, the energy accumulated in the capacitor “breaks through” the transistor, and current passes through the LED. It flashes for a short time and then goes out again as the transistor turns off again.
Then the flasher operates in cyclic mode and all processes are repeated.
Necessary materials and radio components
To assemble an LED flasher with your own hands, powered by a 12 V power source, you will need the following:- soldering iron;
- rosin;
- solder;
- 1 kOhm resistor;
- capacitor with a capacity of 470-1000 μF at 16 V;
- transistor KT315 or its more modern analogue;
- classic LED;
- simple wire;
- 12V power supply;
- matchbox (optional).
The last component acts as a housing, although the circuit can be assembled without it. Alternatively, a circuit board can be used. The mounted mounting described below is recommended for beginner radio amateurs. This assembly method allows you to quickly navigate the circuit and do everything right the first time.
Flasher assembly sequence
The production of a 12 V LED flasher is carried out in the following sequence. The first step is to prepare all the above components, materials and tools.For convenience, it is better to immediately fix the LED and power wires to the case. Next, a resistor should be soldered to the “+” terminal.
The free resistance leg is connected to the emitter of the transistor. If KT315 is placed with the marking down, then this pin will be on the far right. Next, the emitter of the transistor is connected to the positive terminal of the capacitor. You can identify it by the markings on the case - “minus” is indicated by a light stripe.
The next step is to connect the collector of the transistor to the positive terminal of the LED. KT315 has a leg in the middle. The “plus” of the LED can be determined visually. Inside the element there are two electrodes of different sizes. The one that is smaller will be positive.
Now all that remains is to solder the negative terminal of the LED to the corresponding conductor of the power supply. The negative of the capacitor is connected to the same line.
The LED flasher on one transistor is ready. By applying power to it, you can see its operation according to the principle described above.
If you want to reduce or increase the blinking frequency of the LED, you can experiment with capacitors with different capacities. The principle is very simple - the larger the element’s capacity, the less often the LED will blink.
The master reveals the secret of a simple LED flasher with sound, built with his own hands using electronics from a broken electronic-mechanical watch.
How to make a flasher with sound with your own hands
To operate, you need a mechanism from an electronic-mechanical clock with a ticking motion. A broken mechanism will also work, since the malfunction is 99% due to damage to the mechanics. Please note that a smooth-running mechanism is not suitable for crafts. It is easy to distinguish the mechanisms; if you look carefully at the photographs, 3 large gears are clearly visible under the body of the ticking clock, but under the body of the smooth running mechanism there are four gears. The process of removing the electronics board is clearly shown in the video. Next, work with the circuit must be carried out according to the following instructions:
1. We remove all the mechanics with our own hands and put them aside. The wires from the coil can be broken.
2. Mark the polarity of the power terminals on the board. Carefully pry up the electronics board and remove it.
Ticking mechanism
3. Tin the contact pads with solder. This must be done quickly and carefully. When overheated, the pads easily peel off and then break off.
4. Solder the power conductors. The clock chip will operate when supplied with a voltage of 1.5 to 5 Volts.
5. Solder a TR1203 type sound emitter and any LED to the board, depending on what purposes you want to use the resulting circuit. Watch the video and photo of the flasher circuit. The flasher will work and should blink the LED every second, and then beep. This is perhaps what distinguishes the circuit from all similar flashing lights. You can connect two LEDs to the circuit and they will flash sequentially and alternately, why not a ready-made controller for flying models of replica airplanes?
It is recommended to start discovering the world of radio electronics, full of mysteries, without specialized education, by assembling simple electronic circuits. The level of satisfaction will be higher if the positive result is accompanied by a pleasant visual effect. The ideal option is circuits with one or two flashing LEDs in the load. Below is information that will help in implementing the simplest DIY schemes.
Ready-made flashing LEDs and circuits using them
Among the variety of ready-made flashing LEDs, the most common are products in a 5 mm housing. In addition to ready-made single-color flashing LEDs, there are two-terminal versions with two or three crystals of different colors. They have a built-in generator in the same housing with the crystals, which operates at a certain frequency. It issues single alternating pulses to each crystal according to a given program. The blinking speed (frequency) depends on the set program. When two crystals glow simultaneously, the flashing LED produces an intermediate color. The second most popular are flashing light-emitting diodes controlled by current (potential level). That is, to make a LED of this type blink, you need to change the power supply at the corresponding pins. For example, the emission color of a two-color red-green LED with two terminals depends on the direction of current flow.
A three-color (RGB) four-pin flashing LED has a common anode (cathode) and three pins for controlling each color separately. The flashing effect is achieved by connecting to an appropriate control system.
It’s quite easy to make a flasher based on a ready-made flashing LED. To do this, you will need a CR2032 or CR2025 battery and a 150–240 Ohm resistor, which should be soldered to any pin. Observing the polarity of the LED, the contacts are connected to the battery. The LED flasher is ready, you can enjoy the visual effect. If you use a Krona battery, based on Ohm's law, you should select a resistor of higher resistance.
Conventional LEDs and flasher systems based on them
A novice radio amateur can assemble a flasher using a simple one-color light-emitting diode, having a minimum set of radio elements. To do this, we will consider several practical schemes, characterized by a minimum set of radio components used, simplicity, durability and reliability. 
The first circuit consists of a low-power transistor Q1 (KT315, KT3102 or a similar imported analogue), a 16V polar capacitor C1 with a capacity of 470 μF, a resistor R1 of 820-1000 ohms and an LED L1 like AL307. The entire circuit is powered by a 12V voltage source.
The above circuit works on the principle of avalanche breakdown, so the base of the transistor remains “hanging in the air”, and a positive potential is applied to the emitter. When turned on, the capacitor is charged to approximately 10V, after which the transistor opens for a moment and releases the accumulated energy to the load, which manifests itself in the form of LED blinking. The disadvantage of the circuit is the need for a 12V voltage source.
The second circuit is assembled on the principle of a transistor multivibrator and is considered more reliable. To implement it you will need:
- two KT3102 transistors (or their equivalent);
- two 16V polar capacitors with a capacity of 10 µF;
- two resistors (R1 and R4) of 300 Ohms each to limit the load current;
- two resistors (R2 and R3) of 27 kOhm each to set the base current of the transistor;
- two LEDs of any color.
In this case, a constant voltage of 5V is supplied to the elements. The circuit operates on the principle of alternate charge-discharge of capacitors C1 and C2, which leads to the opening of the corresponding transistor. While VT1 discharges the accumulated energy of C1 through the open collector-emitter junction, the first LED lights up. At this time, a smooth charge of C2 occurs, which helps to reduce the base current VT1. At a certain moment, VT1 closes, and VT2 opens and the second LED lights up.
The second scheme has several advantages:
- It can operate in a wide voltage range starting from 3V. When applying more than 5V to the input, you will have to recalculate the resistor values so as not to break through the LED and not exceed the maximum base current of the transistor.
- You can connect 2–3 LEDs to the load in parallel or in series by recalculating the resistor values.
- An equal increase in the capacitance of the capacitors leads to an increase in the duration of the glow.
- By changing the capacitance of one capacitor, we get an asymmetrical multivibrator in which the glow time will be different.
In both options, you can use pnp transistors, but with correction of the connection diagram.
Sometimes, instead of flashing LEDs, a radio amateur observes a normal glow, that is, both transistors are partially open. In this case, you need to either replace the transistors or solder resistors R2 and R3 with a lower value, thereby increasing the base current.
It should be remembered that 3V power will not be enough to light an LED with a high forward voltage value. For example, a white, blue or green LED will require more voltage.
In addition to the considered circuit diagrams, there are a great many other simple solutions that cause the LED to blink. Beginning radio amateurs should pay attention to the inexpensive and widespread NE555 microcircuit, which can also implement this effect. Its versatility will help you assemble other interesting circuits.
Application area
Flashing LEDs with a built-in generator have found application in the construction of New Year's garlands. By assembling them in a series circuit and installing resistors with slight differences in value, they achieve a shift in the blinking of each individual element of the circuit. The result is an excellent lighting effect that does not require a complex control unit. It is enough just to connect the garland through a diode bridge.
Flashing light-emitting diodes, controlled by current, are used as indicators in electronic technology, when each color corresponds to a certain state (on/off charge level, etc.). They are also used to assemble electronic displays, advertising signs, children's toys and other products in which multi-colored flashing arouses people's interest.
The ability to assemble simple flashing lights will become an incentive to build circuits using more powerful transistors. With a little effort, you can use flashing LEDs to create many interesting effects, such as a traveling wave.
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