Flashing LED - light-emitting diode is, in which case is already included resistor and the capacity to set the operation mode.
general information
In the literature, there is evidence that the marking ends flashing LED to the Latin letter 'F. Probably - from the English flashing. Consideration showed that manufacturers prefer to label flashing LEDs through the letter 'B. From English blinking. So called flashing LEDs abroad. So, do not believe every source possible.
Flashing LED in appearance is no different from the usual, it demonstrates the high contact resistance, and the electrodes are designed such that a large capacitance value (capacitor) between them. These two elements define a time constant control circuit transistor, IC, etc. because of lack of understanding of the audience the main question - how to use the flashing LED on practice.
When the DC voltage charged to the capacitor circuit potential and the process stops. Therefore, a key switch, providing discharge. How to create flashing schemes for conventional LEDs. In this regard, the presentation starts with how to get without the flashing LED flicker.
The main question becomes the necessity of such claims. Scientific evidence shows that the variable light output is much more effective draws a person's attention, rather than permanent. Flashing LED noticeable simple - this is an obvious fact! On the mountain climber in distress attract attention if a mirror try to send a signal. Such brilliance is noticeable throughout the line of sight, and this - tens of kilometers. Affected topic seriously, in support of present materials:
- Corpses on Mount Everest: youtube.com/watch? v = EZ3vK-pvBKs. It is believed that the first conquerors of the mountain ever stayed there and died already on the way down. The first still is not found, the second lay (1996) in the west of the path. If the team was on duty, probably people would come back alive. Morality? Climbing for 50 thousand. dollars in the mountain, leave the bottom of the can to help (pre-paid). The coordinates of the radio yet learned not to transfer, flashing LEDs will have a good service for climbers. For your information: the gap in the clouds mountain visible almost to the top.
- Group Dyatlov: murders.ru/Dyatloff_group_1.html#20. If serendipitously breakaway group Yuri Yudin took care of the conventional signs and to insure the team, the outcome would have been different. Real sources indicate that at the scene after the accident burned a fire. Morality? These trips can not perform without a net.
Thus, the flashing LED can provide a variety of schemes, with not all belong to the entertainment industry. While most of the equipment is used as display, for example, charge unit. Anyone who wants to make sure that the green LED is invisible on the system case peripheral vision, but can be seen flashing.
A computer running Windows 10 is turned off for a long time, when power is lost ahead of time, users will appreciate the flashing LED. In color maybe a simple way to monitor progress. New system blocks are "switching on alarm" option when energized. Network TN-C-S provide poor filtering system boards interference perceived as a signal to turn on. Consequently, at the end of the day you want to remove the supply of electricity is final. If power strips are turned off before the time, you could lose data even have to reinstall the system with its consequences.
Green LED is not easy to notice, especially if the system unit is lit by the sun's rays. A neighbor indicator showing the hard disk activity, the most interesting moments is disabled, fulfilling the law of Murphy. mainboard developers have managed to make the presence of LED flash power when turned off. Similarly, you want to make and standby time, the first widespread breakdown in the modern computer is considered a loose coupling of the power cord (the second - the lack of housing grounding). By flashing LED monitor is extremely convenient.
How to connect the LED to blink
The simplest scheme
The first circuit is used for a long time. In the USSR, it is already known and is based on the avalanche breakdown of the collector-emitter voltage of the bipolar transistor. The capacitor is charged from the mains, and the voltage is divided between the LED and semiconductor switches. Denomination determining resistor and a capacitor charge time constant and as a consequence, the frequency of blinking.
Avalanche breakdown is similar to the electric arc and shows a negative differential resistance. Until the capacitor voltage falls, the LED operates safely. Finally, the potential difference reaches a certain threshold, p-n-junction is closed. More precisely, between the emitter and the collector of the two p-n-junction. It follows that the transistor may be replaced with any nonlinear element, demonstrating the current-voltage characteristic of the negative differential resistance. In this group fall avalanche diodes and tunnel.
Most bipolar transistors exhibit the desired characteristic. Choose the one limiting the reverse emitter-collector voltage is less than the applied power. Avalanche breakdown occurs easier in the emitter junction. Accordingly, it will need to include in the reverse direction.
The oscillator circuit
The Internet is discussed in the multivibrator circuit. Highlighted other generators, utility and ease of collection setup. Relay devices are used today. They belong to the class contact generators, indicating the presence of moving parts.
Pulse-pair, constructed of two relay detects a simple advantage - an obvious work of measurement devices for debugging is not required. Figure depicts a possible embodiment of the circuit in the electromagnetic relay is opened and closed. At the initial time the power is fed through the coil contact 2P 1P. As a result, the first relay closes. 2P powered and:
- Breaks his contacts in the output circuit, where there is a LED. He goes out.
- Ceases to nourish 1P.
Lost power to the relay 1P, it opens. As a result, the normally closed contacts 2P return the power LED and H1. Scheme rolled back to the original state, begin a new cycle of operation. The switching speed is determined by the characteristics of the whole relay. For further adjustment is permissible to add delay the release of the elements in the circuit.
The second figure shows a generator, massively used in the art. It consists of a pulse-pair mode of operation discussed above, and an auxiliary relay with the problem of time delay. Control buttons (KU) define the desired settings.
When the manual pressing device into operation. Brush the stepping (SI) go to the slats on the slat. Switches. First through the lamella 0 button and coil 1P 1P potential is applied to the relay. It works and performs these steps:
- Interrupts the supply circuit of the coil 2P where previously flowed current.
- Prepares relay D to fire.
When passing the brush on the lamella 1 is de-energized relay 1P, 2P opens its contacts. Relay 1P disappears. 2P is activated by feeding power to the H1. The circle is closed. On the second contact 2P connected LED starts flashing.
If pressed KU, brush SHI gets the second lamella, and when the relay 1P work D. Last time on the slow switch 2P. In this case, temporarily LED stops flashing, the period will be extended.
The circuit of the multivibrator
Multivibrators called transistor generator of rectangular pulses. Because of the power elements are often chosen bipolar. According to the classification multivibrators are non-contact and generators are often used to power the LED, causing flash.
Transistors get easier than specialized chips, which makes the popularity of the proposed technical solutions. Contactless generators differ long service life, and the switching speed is adjusted nominal choice of passive components. Multivibrators produce pulses of rectangular shape. However, similar states of contact generators. In this case, it's good.
Under the scheme of the base of the first transistor is supplied through the capacitor voltage of the second manifold opening key. At this point, two simultaneous processes:
- Managing the capacitor discharges through the last resistor and emitter-base junction of the opposite transistor.
- Through its collector resistor and an internal charge another capacitor.
The circuit operates as a swing, which, however, is characteristic for any rectangular pulse generators. And R par with permissible change duty ratio and period of oscillation. The latter is achieved in an asymmetric pattern.
Generators on chips
The timer on the chip 555 allows you simple ways to make the LED blink. For this radio amateurs use a standard 9 volt battery with. Several resistors, chip and capacitor - everything you need in this situation. As before, the time constant given by the capacitor size of passive elements. To debug circuit may use the trimmer or variable capacity.
How to use the flashing LED
It is easy to notice that the LED is used ordinary schemes. Blinking is distinguished by its own capacity and large contact resistance. These parameters are measured by simple using a tester. For a successful course of experiments useful to know that the longer leg of the LED is considered to be the anode, and here you need to carefully apply a plus. The element does not tolerate high reverse voltages and certainly fails, unless safety precautions.
After the measurement, the tester is recommended to draw an equivalent circuit of the LED. Draw on it the capacity and resistance. Then the calculation of the switching time is carried out with the use of the portal sections of the material:
- Parallel and series connection of the conductors.
- Series connection of capacitors.
- The parallel connection of capacitors.
Information from the topics will help to calculate the characteristics of almost any compound passive elements. Thereafter calculated constant charging circuit. This is done by multiplying the nominal values R and S. Full time of transition from one state to another is equal to the calculated three periods. For example, a 10 microfarad capacitance for capacitor 20 and the value of k is 200 ms. Consequently, the LED will flash with a frequency of 2-3 Hz, two or three times per second.
