Light pulse generators. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur

 Comments on the article

A variety of "flashing lights" - generators of light pulses - are very popular among beginner radio amateurs. They can be installed on children's toys, used in attractions, placed in a conspicuous place in the car to simulate the action of a watchdog. The proposed selection introduces some variants of such devices.

... with trinistors

Relatively simple "flashing lights" are obtained using trinistors. True, the peculiarity of the operation of most trinistors is that they open when a certain voltage (current) is applied to the control electrode, and to close them, it is necessary to reduce the anode current to a value below the holding current.

If the trinistor is powered from an AC or pulsating voltage source, it will automatically close when the current passes through zero. When powered by a constant voltage source, the trinistor will not close just like that, you will have to use special technical solutions

A diagram of one of the options for "flashing lights" on trinistors is shown in fig. one.

The device contains a generator of short pulses on a single-junction transistor VT1 and two cascades on trinistors. An incandescent lamp EL2 is included in the anode circuit of one of the trinistors (VS1).

The device works like this. At the initial moment after power is applied, both trinistors are closed and the lamp is off. The generator generates short powerful pulses with an interval determined by the parameters of the R1C1 chain. The first impulse will go to the control electrodes of the trinistors, and they will open. The lamp will light up. Due to the current flowing through the lamp, the trinistor VS2 will remain open, but VS1 will close, since its anode current, determined by resistor R2, is too small. Capacitor C2 will begin to charge through this resistor and by the time the second pulse of the generator appears, it will be charged. This pulse will open the trinistor VS1. and the output of the capacitor C2, left according to the scheme, will be briefly connected to the cathode of the trinistor VS2. But even such a connection is enough for the trinistor to close and the lamp to go out.

Thus, both trinistors will be closed, capacitor C2 will be discharged. The next pulse of the generator will lead to the opening of the trinistors, the described process will be repeated. The lamp flashes at a frequency half the frequency of the generator.

For the elements indicated in the diagram, you can use an incandescent lamp (or several lamps connected in series or in parallel) with a current of up to 0,5 A. If you use all the capabilities of these trinistors, it is permissible to use a lamp that consumes current up to 5 A. In this case, for reliable closing trinistor VS2, the capacitance of capacitor C2 must be increased to 330 ... 470 uF. Accordingly, it will be necessary to increase the capacitance of the capacitor C1, so that during the periods between the pulses of the generator, the capacitor C2 has time to charge. SCR VS2 should be placed on a small radiator.

Details of the flasher are mounted on a printed circuit board (Fig. 2) from one-sided foil-coated getinax or fiberglass. Oxide capacitor C2 - necessarily aluminum, series K50-6. K50-16, K50-35.

If the lamp current does not exceed 0,5 A, one of the trinistors can be replaced with a low-power one, for example, KU101A (Fig. 3).

Since the voltages on the control electrodes of the trinistors, at which they open, are different, a tuning resistor R2 is introduced into the device, with the help of which the optimal mode of their operation is selected. In addition, increase the resistance of the resistor (R3) in the anode circuit of the trinistor VS1.

The details of the device are placed on a printed circuit board (Fig. 4) made of foil material.

The adjustment of structures is reduced to setting the required frequency of "blinking" of the lamp by selecting capacitor C1. If the incandescent lamp lights up but does not go out, then either the trinistor VS1 does not close (you should increase the resistance of the resistor R2 in the first flasher or R3 in the second), or the capacitor C2 does not have time to charge. Then it is desirable to reduce its capacity, and even better - the switching frequency. In the second flasher, you need to set the trimmer resistor engine to a position in which both trinistors work steadily.

... with bicolor LEDs

About two-color LEDs (they are also called two-chip) was described in the reference sheet "Dual Chip Light Emitting Diodes"in "Radio". 1998. No. 11, pp. 57-60; 1999, No. 1, pp. 51-54. They can be widely used in a number of amateur radio designs. Here, for example, is a generator (Fig. 5), which can serve as an overload indicator, an indicator of operating modes.It is not difficult to build it into an appropriate electronic device.In addition to the two-color LED HL1, it uses a TTL (TTLSh) structure microcircuit.

The basis of the design is a pulse generator assembled on logical elements DD1.1. DD1.2. Cascades on elements DD1.3 are connected to the generator. DD1.4. A two-color LED is connected to their outputs (through current-limiting resistors R2 and R3). When applied to the control input (pin 1 element DD1) low logic level, the generator will not work and the output of the element DD1 will be set to a high level, and the output of DD1.3 will be low. The HL1.4 LED crystal, right according to the scheme, will light up. The color of the glow can be red or green, depending on how the LED is connected (with the option for connecting the outputs indicated on the diagram, the color will be red).

If such a generator is used as an emergency indicator, then the right crystal should be green, and its glow will indicate the normal operation of the controlled node.

In the event that a control input arrives (for example, when a fault occurs) of a high logic level, the generator will start to work. The pulses will go to the logic elements DD1.3, DD1.4, their state will change in turn, and the LED will change the color of its glow with the frequency of the generator pulses.

Instead of that indicated on the diagram, it is permissible to use similar microcircuits of the K155 series. 530. K531. KR531, 533. K555.1553, KR1533, as well as other microcircuits of the TTL or TTLSH structure (except for open-collector elements). Trimmer resistor - SDR, constant - MLT, S2-33. capacitor - K50-6, K50-16.

Establishing the device is reduced to setting the stable generation mode at the minimum frequency by the resistor R1. The desired pulse repetition rate can be set by selecting a capacitor. In order for changes in the color of the glow to be noticeable, this frequency should be no more than a few hertz. The brightness of the LEDs can be slightly increased by selecting resistors R2, R3 of lower resistance.

This device uses two-color LEDs with separate leads from the crystals. If you use LEDs with back-to-back connection (with two leads) KIPD41A-KIPD41M or any of the KIPD45 series, the circuit must be changed in accordance with Fig. 6.

In order for the LED not to change the color of its glow, but to briefly flash alternately in different colors, the circuit must be changed in accordance with Fig. 7.

In this embodiment, when a high level appears at the outputs of the elements DD1.3, DD1.4, the capacitor C2 will be charged and the left LED crystal will flash for a short time. When a low logic level appears, the capacitor will begin to discharge, the right crystal will flash. By selecting capacitor C2, the desired flash duration is achieved.

The scheme of the generator of light pulses on a microcircuit of the CMOS structure is shown in fig. 8. Since this chip has a low load capacity, to match the generator, made on the elements DD1.1 .DD1.2. and buffer element DD1 .3 with LED HL1 transistors VT1, VT2 are introduced into the device. Here, the control of the generator is also carried out by applying to the output 1 of the element DD1.1 logical levels. At a low level, the generator does not work, the right LED crystal glows according to the scheme. When a high level is received, the generator turns on, the color of the LED changes with the frequency of the generator pulses.

The generator frequency is roughly set by selecting the capacitor C1, and smoothly by the resistor R1. The brightness of the glow is set by selecting resistors R2, R3.

The elements of most CMOS microcircuits work well in this generator (except for open-drain elements). Transistors - any of the KT315, KT3102 series, capacitor C1 - K10-17, K73, MBM, C2 - K50-6, K50-35, K52, resistors - the same as in the previous generator.

For LEDs with back-to-back radiating crystals, the circuit must be changed in accordance with Fig. 9. By selecting capacitor C3, you can set a different mode of operation of the LED: with an increase in its capacity, the color of the glow will change abruptly; if you reduce it, short flashes will appear with an alternate change in the color of the glow. More smoothly, the mode is set by selecting the resistor R2.

Transistors - any of the series indicated in the diagram. The remaining parts are of the same types as in the previous designs.

Author: I. Nechaev, Kursk

See other articles Section Beginner radio amateur.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive Electronics to help drunk and bad drivers 28.03.2019 Volvo Cars has developed a safety system that can save drunk and inattentive drivers from an accident. As stated in a company press release, we are talking about a system of built-in cameras and other sensors that control the behavior of a person behind the wheel. When the driver begins to ignore the signals of the car, informing about the possibility of an accident, the assistant systems automatically turn on. These include, in particular: reducing speed (up to a complete stop of the car), automatic parking in a safe place, as well as alerting emergency services through Volvo on Call. The systems are triggered if the sensors detect a lack of steering, exit from the track, a sharp wobbling from lane to lane, the driver's eyes are closed, or his reaction to the traffic situation is too slow. The cameras are equipped with all Volvo models built on the SPA2 platform. The first such cars will appear in 2020.

Other interesting news:

▪ Bullets with laser guidance

▪ Smart lamps will help you find goods in the store

▪ Music lessons develop intelligence

▪ Blossom Automatic Watering System

▪ The largest silicon carbide power electronics factory

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Labor protection. Selection of articles

▪ article Pique vests. Popular expression

▪ How much gold is in an Olympic gold medal? Detailed answer

▪ backpack article. Tourist tips

▪ article Modernizing a six-string guitar. Encyclopedia of radio electronics and electrical engineering

▪ article Mysterious glass of water. Focus Secret

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024