Flashing LEDs: appointment, description

Often on the shelves of shops selling radio parts, you can find flashing LEDs. They are different in strength and color of luminescence. Flashing LEDs (MSD) are semiconductor elements with built-in integral pulse generators with a flash frequency of 1.5-3Hz.

Many radio amateurs believe that these devices are useless and it is better to replace them with cheaper LED indicator lights. Perhaps in some ways they are right. However, MSD also have a right to exist. Let's try to figure out what the advantages of such products are.

Flashing LEDs, in fact, are complete functional devices, the main purpose of which is to attract attention, that is, the function of light signaling. It is also worth noting that the blinking semiconductor elements do not differ in size from standard indicator LEDs. However, despite the compact size, the MSD includes semiconductor chip generators, as well as some additional elements. If we design a pulse generator on conventional radio components, then this design would have quite solid dimensions. It should be noted that the flashing LEDs are quite versatile. The supply voltage of such elements lies within the limits of 1.8-5 V for low-voltage devices and 3-14 V for high-voltage devices. The photo below shows a blinking 12 volt LED.

Advantages of MSD:

- wide range of supply voltage (up to 14 volts);

- small overall dimensions ;

- a fairly compact device for light signaling;

- Different colors of radiation. Some variants of flashing LEDs have several built-in color diodes with different flash intervals (the photo shows a flashing yellow LED);

- The use of MSD is justified in small devices, in which stringent requirements are imposed on the size of the element base and the consumption of electricity. These diodes, thanks to their electronic circuit, assembled on MOS structures, have a low current consumption at a sufficiently high luminescence power;

- flashing semiconductor device can replace even a functional unit.

In principle, the graphical representation of the MSD differs from the conventional LED only in the dotted lines of the arrows, which symbolizes the flashing properties of the element.

Let's take a closer look at the design of the flashing LEDs. Through the transparent case of the element, one can see that the diode is structurally composed of two parts. The light-emitting crystal is placed on the base of the cathode (negative) electrode, and the chip generator is located on the base of the anode (positive electrode). All parts of this device are connected by three golden bridges. The chip generator is a high-frequency master oscillator, which works constantly, its frequency fluctuates around 100 kHz. Also on the diagram of the flashing diode there is a divider, assembled on logic elements. It divides the value of high frequency to a level of 1.5-3 Hz. You may ask: "And why is a high-frequency generator with a divider used, why it was impossible to use a low-frequency generator, and thereby simplify the design?" This is due to the fact that the implementation of a low-frequency generator requires the presence of a large-capacity capacitor for the time-determining circuit. To implement such a capacitor would need a much larger area than using a high-frequency generator.

So we looked at what the blinking LED is. And to the question about what is better - the technology of MSD or traditional indicator diodes, we will answer that despite the cheapness of the second, the flashing diodes also found their scope and do not constitute traditional competition.