Flashing LEDs are used in various signal circuits, billboards and signs, and electronic toys. The scope of their application is quite wide. A simple LED flasher can also be used to create a car alarm. It must be said that this semiconductor device is made to blink by a built-in microcircuit (CHIP). The main advantages of ready-made MSDs: compactness and a variety of colors, allowing you to colorfully design electronic devices, for example, an advertising board to attract the attention of buyers.

But you can make a flashing LED yourself. Using simple diagrams, this is easy to do. How to make a flasher, having little skills in working with semiconductor elements, is described in this article.

Transistor flashers

The simplest option is an LED flasher on a single transistor. From the diagram you can see that the base of the transistor is hanging in the air. This non-standard inclusion allows it to work as a dinistor.

When the threshold value is reached, a breakdown of the structure occurs, the transistor opens and the capacitor discharges to the LED. Such a simple transistor flasher can be used in everyday life, for example, in a small Christmas tree garland. To manufacture it you will need quite accessible and inexpensive radioelements. A DIY LED flasher will add a little charm to the fluffy New Year's beauty.

You can assemble a similar device using two transistors, taking parts from any radio equipment that has served its purpose. The flasher diagram is shown in the figure.

For assembly you will need:

• resistor R = 6.8–15 kOhm – 2 pieces;
• resistor R = 470–680 Ohm – 2 pieces;
• n-p-n-type transistor KT315 B – 2 pieces;
• capacitor C = 47–100 µF – 2 pieces;
• low-power LED or LED strip.

Operating voltage range 3–12 volts. Any power source with these parameters will do. The blinking effect in this circuit is achieved by alternately charging and discharging the capacitors, which entails the opening of the transistors, as a result of which current appears and disappears in the LED circuit.

Flashing LEDs can be obtained by connecting the leads to several multi-colored elements. The built-in generator produces pulses for each color in turn. The frequency of the blinking pulse depends on the specified program. You can please your child with such a cheerful flashing if you install the device in a children's toy, for example, a car.

A good option would be if you take a three-color flashing LED that has four pins (one common anode or cathode and three color control pins).

Another simple option, for assembly you will need CR2032 batteries and a resistor with a resistance of 150 to 240 Ohms. A flashing LED will be obtained if all the elements in one circuit are connected in series, observing the polarity.

If you can collect funny lights by the simplest scheme, you can move on to a more complex design.

This scheme LED flashers work as follows: when voltage is applied to R1 and capacitor C1 is charged, the voltage across it increases. After it reaches 12 V, a breakdown of the p-n junction of the transistor occurs, which increases the conductivity and causes the LED to glow. When the voltage drops, the transistor closes and the process starts over again. All units operate at approximately the same frequency, if you do not take into account a small error. An LED flasher circuit with five blocks can be assembled on a breadboard.

Flasher circuits on transistors and microcircuits You can easily find it on the Internet. However, most of them are based on multivibrators, which means a relatively large number of parts and, accordingly, dimensions. And also quite high voltage source necessary to light the LED. Is it possible to get by with a minimum of parts and one 1.5-volt battery? Separately, it is not difficult to fulfill these conditions. Well-known blocking generators allow you to power an LED with a voltage of 1.5 Volts. Popular, although the transistor will operate in the base-off mode, the so-called “avalanche” mode, and the performance of the circuit will depend on many factors: transistor type, temperature, etc. Yes, and the supply voltage in this version requires at least 9 Volts. Flasher circuit using one transistor shown in the figure.

LED flasher on a chip- free from these shortcomings. The simplest option Such a device can be made in 15 minutes, including heating the soldering iron. To do this, you will need a Chinese alarm clock, of which you can find a dozen in homemade garbage, and a couple of parts: a diode and a capacitor. You can use any low-power diode; I took a 47 µF capacitor. You can experiment with the container. It affects the LED flash energy. The diagram is shown in the figure.
Points A and B must be connected to the pins of the microcircuit going to the coil that controls the clock pendulum. The coil itself must be removed. The LED will flash with a period of 2s. and in this mode it can work for years without replacing the “finger”. By the way, the same result can be obtained with the Soviet electronic-mechanical alarm clock “Slava”, built on a special microcircuit UTP-T45. There is also a transistor, it controls the alarm clock. You can remove it, or you can leave it, it will work LED flasher-beeper. A short video to make sure the circuit is working;

In all the designs below, incandescent lamps can and should be replaced with LEDs, with the selection, of course, of a current-limiting resistor.

RC - generator.

The most common circuit of this class of generators is
cauldron in the picture. In this case it is very low frequency, it can be smoothly changed within small limits (from fractions of Hz to several Hz).

RC oscillator frequency determined by the parameters of the phase-shifting chains and can be calculated using the approximate formula f = 5300: RC; here f is the frequency in Hz. R and C are the resistance and capacitance of one of the phase-shifting chains, respectively in kOhm and μF.

Flashers on multivibrators and their application.

Pulse warning light on transistors. There are times when it is simply necessary to have a flashlight with you. In Fig. given circuit diagram such a flashlight that sends pulses of light lasting 0.1 s with a periodicity of about 2 s. The pulse mode of an incandescent lamp with a voltage of 2.5 V is provided by a multivibrator using transistors T1 and T2 of various structures. Such a multivibrator contains only one positive feedback capacitor and one initial bias resistor (C1 and R1). Its main advantage is that the multivibrator consumes current only at those moments in time when transistor T2 is open, i.e. when lamp L1 is lit for 0.1 s every 2 s. Transistor T1 must be silicon, type MP114-MP116. In extreme cases, it is possible to use germanium transistors such as MP40 - MP42, but then the current consumption will increase. Incandescent lamp 2.5 X O, 15 A.
Electrified warning triangle transport. According to the rules traffic In the event of a forced stop of a vehicle on the roadway, an emergency stop sign in the form of an equilateral triangle and equipped with reflective reflectors must be installed at a certain distance from this vehicle (in front of it). At night, the sign must be additionally illuminated. Obviously, to illuminate the signal in the dark or in bad weather, it is best to install incandescent lamps on such a sign and power them from the on-board battery. This solution is quite acceptable if the stop is intended to be short-term. But when a vehicle is parked for a long time, such an electrified sign can completely drain the battery. Therefore, it is advisable that the sign lamps are turned on periodically. This mode of operation of the lamps allows you to reduce current consumption and further increase the visibility of the sign on the road. In Fig. A schematic diagram of an electrified warning triangle is shown, equipped with six backlight lamps that periodically turn on and off. The basis of the scheme is symmetrical multivibrator on transistors medium power. A multivibrator is usually called a device consisting of two amplifier stages, in which the output of one is connected through a transition capacitor to the input of the second, and the output of the second through the same second capacitor is connected to the input of the first. These capacitors are indicated in Fig. like C1 and C2. To create an initial bias at the bases of the transistors, resistors R1, R2 are used. Since capacitors C 1 and C 2 create a strong positive feedback, then both amplification capacitors become elements of the generator. The frequency of its generation is inversely proportional to the product of the capacitance of the capacitor and the resistance of the resistor. A feature of the operation of the multivibrator is that
that each of the transistors works in turn with the other, i.e. if one transistor
is completely open and therefore the lamps connected to the circuit of its collector glow brightly, then at the same time the other transistor is completely closed, the collector current is very small, and therefore the lamps in its
the circuits do not light up. Then the transistors will switch roles. Frequency
switching of lamps of a device made according to the circuit in Fig. is about 0.5 Hz.
Diodes D 1 - D 4 V this device have an auxiliary purpose. They are connected according to a bridge rectifier circuit and are designed to ensure operation with any polarity of connection to the source. You can do without diodes, but then you need to connect the wire leading to the lamps to the negative pole, and the bottom wire in the diagram to the positive pole of the battery.

Transistors T 1 and T 2 can be of type P213-P217 with any letter indices, but it is still better if their current transfer coefficients h 21e are equal to 30-40.

. Multivibrator frequency approximately calculated by the formula: f = 7250: RC, where f is the frequency in Hz. R and C are the resistance and capacitance of one of the basic RC circuits, respectively, in kOhm and μF.

Reviews (2) for “circuits of flashing lights on transistors and microcircuits”

Thank you, of course, but you know what I, as a person who has been afraid of transistors since school, with their abstruse characteristics and voltage adjustments, would like to advise: take the remote control from an old unnecessary TV, it’s essentially a flashlight flashing an IR LED, if you replace the LED with an optocoupler, then you can connect to it whatever you want, a flasher, a tweeter... just short-circuit the remote control button with the “melody” you like and it will send its Morse code forever. Only, unfortunately, the button must be pressed after the power is applied, well, it’s easier to make a delay line than using black magic p-n junction study.

The second diagram is not correct. You need a diode in parallel with the LED, power in series through a capacitor.

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 closely 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.

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?

Answer

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This circuit can be used to indicate an alarm. The homemade product is connected to a stabilized power source with a voltage of 12 V. Such a source can be a power supply with an adjustable output voltage, purchased on the radio market. The power supply is called stabilized because it contains a stabilizer that keeps the output voltage at a certain level.

The circuit is as simple as possible, contains only 4 parts: transistor KT315 p-p-n structures, a 1.5 kOhm resistor, an electrolytic capacitor of 470 μF and a voltage of at least 16 V (the capacitor voltage should always be an order of magnitude greater than the homemade supply voltage) and an LED (in our case, red). For correct connection parts you need to know their pinout (pinout). The pinout of the transistor and LED of this design is shown in Fig. 5.2. Transistors of the KT315 series are the same in appearance as KT361. The only difference is the placement of the letter. For the former, the letter is placed on the side, for the latter - in the middle.

Now, using a soldering iron and wires, let's try to assemble our device. In Fig. Figure 5.3 shows how you should connect the parts together. Blue lines are wires, thick black dots are solder points. This type of installation is called wall-mounted; there is also mounting on printed circuit boards.

Rice. 5.2. - Pinout:
a) transistor KT315B
b) LED AL307B

Rice. 5.3. - Appearance assembled device
Check that the parts are connected correctly and connect the device to the power supply. A miracle happened - the LED began to flash brightly. Your first homemade product has worked!!!