It is recommended to start learning the basics of electronics with the assembly of simple and intuitive diagrams, therefore, the flasher circuit in various designs and options is the best fit for novice radio amateurs in their difficult path. In addition, these designs can come in handy in everyday use. For example, in the role of festive lighting decorations or as a dummy alarm.
An elementary flasher circuit with six LEDs, a feature of which is simplicity and the absence of active control elements, such as transistors, thyristors or microcircuits.
With the third flashing red LED, two normal red LEDs 1 and 2 are connected in series. When flashing 3 flashes, 1 and 2 will light up with it. The opening diode shunts the green LEDs 4-6, which then go out. When the blinking one goes out, LEDs 1 and 2 go out together with it, while the group of green LEDs 4-6 comes on.
This LED flashing control circuitry creates a chaotic flash effect. The principle of operation is based on an avalanche breakdown of the transition.
When switched on, the capacitance C1 begins to charge through the resistance R1 and therefore the voltage begins to rise on it. While the capacitor is charging, nothing changes. As soon as the voltage reaches 12 volts, an avalanche breakdown of the p-n junction of the semiconductor device will occur, its conductivity increases and therefore, the LED starts to burn due to the energy of the discharging C1.
When the voltage across the capacitor drops below 9 volts, the transistor turns off, and the whole process is repeated from the very beginning. The other five blocks in the circuit work in a similar way.
The resistor and capacitor ratings set the operating frequency of each individual generator. The resistors also protect the transistors from failure during an avalanche breakdown.
The easiest way to assemble a blinking structure is to use the LM3909 ASIC, which is fairly easy to obtain.
It is enough to connect a frequency setting circuit to the microassembly, supply power and, of course, the LED itself. Here is a ready-made device for simulating an alarm in a car.
At the indicated ratings, the blinking frequency will be about 2.5 Hertz
A distinctive feature of this design is the ability to adjust the blinking frequency using the trimmers R1 and R3.
The voltage can be supplied from any or from batteries, the area of use is the entire width of your imagination.
In this design, it is used as a generator and periodically opens and locks the field-effect transistor. Well, the transistor includes chains of ordinary LEDs.
The first and second strings of LEDs are connected in parallel and receive power through the resistance R4 and the channel of the field-effect transistor.
The third and fourth chains are connected through the diode VD1. When the transistor is locked, the third and fourth circuits are on. If it is open, then the first and second sections are shining.
The flashing LED is connected through the resistors R1, R2, R3. During its flash, the field-effect transistor is opened. All parts, except for the battery, are installed on the printed circuit board.
Quite simple amateur radio designs will turn out if you use the usual ones. True, one should remember about their peculiarities of work, namely, that they open when a certain voltage level arrives at the control electrode, and to block them, it is necessary to reduce the anode current to a value less than the holding current.
The design consists of a short pulse generator on a field-effect transistor VT1 and two stages on thyristors. An EL1 incandescent lamp is connected to the anode circuit of one of them.
At the initial moment of time after turning on the power, both thyristors are closed and the lamp does not light up. The generator generates short pulses with an interval depending on the R1C1 chain. The first pulse arriving at the control electrodes opens them, lighting the lamp.
Current will flow through the lamp, VS2 will remain open, and VS1 will close, because its plate current, set by resistance R2, is too small. Capacitance C2 begins to charge through R2 and by the time the second pulse is formed, it will be already charged. This impulse will unlock VS1, and the output of the capacitor C2 will briefly connect to the cathode VS2 and close it, the lamp will go out. As soon as C2 is discharged, both thyristors will be locked. The next pulse of the generator will lead to the repetition of the process will be repeated. Thus, the incandescent light bulb flashes at a frequency that is half the set frequency of the generator.
The basis of the design is a simple multivibrator with two transistors. They can be almost any required conductivity.
I connect the power supply from the size through the resistance, the second wire is ground. LEDs are fixed in the panels from the speedometer and tachometer.
