Short circuit signaling device on the UTC1240A chip. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Short circuit signaling device on the UTC1240A chip. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Protection of equipment from emergency operation of the network, uninterruptible power supplies

Comments on the article

If in the power supply unit (PSU) protection against short circuit (SC) in the load circuit works on the principle of limiting the maximum output current, then some elements of the unit, if it is in protection mode for a long time, can overheat and fail. To prevent this from happening, it is desirable to supplement such a power source with a signaling device that, for example, gives an audible signal in case of a short circuit in its output circuit [1].

Short circuit signaling device on the UTC1240A chip
Fig. 1

The scheme of the proposed sound and light signaling device for short circuit is shown in fig. 1. The device is designed to be built into a power supply unit, in which the voltage on the filter capacitor connected to the output of the bridge rectifier is at least 18 V (such, for example, as the power supply unit described in [2]). The signaling device is made on the basis of an integrated circuit UTC1240A, which is a signal generator of two switched frequencies and is used in ringing devices for wired telephones and apartment calls powered by 220 V. The microcircuit contains a diode bridge rectifier, a zener diode, a Schmitt trigger, clock and tone generators, a stabilizer voltage and output amplifier AF.

If the voltage at the input of the device (i.e., at the output of the PSU stabilizer) is more than 0,7 V, the transistor VT1 is open, and VT3 and VT2 are closed, so the HL1 LED does not light up and there is no supply voltage to the DA1 chip. In the event of a short circuit at the PSU output, the transistor VT1 closes, VT3 opens, the HL1 LED lights up and the transistor VT2 opens. As a result, a supply voltage is supplied to the DA1 chip, the generator assembled on it starts working and the HA1 piezoceramic sound emitter emits a two-tone sound. Resistor R7 determines the oscillation frequency of the generator, capacitor C3 sets the switching frequency of tonal audio frequencies. Capacitor C2 is connected to the output of the built-in diode bridge rectifier of the microcircuit in parallel with the protective zener diode. Resistor R6 - current-limiting in the power supply circuit of the microcircuit.

Short circuit signaling device on the UTC1240A chip
Fig. 2

The signaling device is connected to the power supply unit according to the scheme shown in fig. 2. Here A1 is the PSU voltage regulator, A2 is the signaling device being described, C1 is the PSU filter capacitor. The signaling device turns on when the voltage on this capacitor is 16 V, and turns off when it drops to 11 V. When the PSU is overloaded, the voltage on the capacitor C1 may drop below 16 V, in which case the signaling device may not work during a short circuit. To prevent this from happening, a decoupling diode VD1 and a storage capacitor C1 are installed in the signaling device. The latter ensures the operation of the device for approximately 2 s after a complete loss of supply voltage.

From a voltage source of 18 V, the device consumes a current of about 4 mA when the generator is running and 0,18 mA when it is braked. The voltage amplitude at the outputs of the sound emitter HA1 is approximately 3 V less than the input supply voltage, as long as it does not exceed the stabilization voltage of the protective zener diode built into the microcircuit.

Short circuit signaling device on the UTC1240A chip
Fig. 3

All parts of the device, except for the sound emitter and the LED, are placed on a printed circuit board, the drawing of which is shown in Fig. 3. Resistors - C1-4, C1-14, MLT, RPM, capacitor C3 - small-sized film, the rest - oxide imported (C1 is mounted parallel to the board and glued to it with Moment glue). We can replace the KD208A diode with any of the KD209, KD243, KD247, 1N4001 - 1 N4007, UF4001-UF4007 series. Instead of 2SC3199 transistors, SS9011, BC547, 2SC1815, 2SC1845 and any of the KT6111, KT6117 series are suitable, and instead of 2SA1015 - 2SA992, 2SA1175, BC557, MPSA43, as well as any of the KT6112, KT668 series. When choosing a replacement, it should be taken into account that the replacement transistor may have a pinout different from that shown in fig. 3. With a relatively small voltage at the input of the PSU stabilizer, transistors with a lower allowable collector-emitter and collector-base voltage can be used.

Instead of the RL50-SR113 LED, you can use any other continuous glow, for example, from the KIPD21, KIPD40 series. If the light indication of the signaling device operation is not needed, the LED can be excluded by installing a jumper instead of it on the board. A possible replacement for the UTC1240A chip is imported L3240, LS1240, LS1240A, LS1241, PSB6520-2, PSB6521-2, PSB6523T or domestic KR1064PP1, KR1091GP1, KR1085PP1. Piezoceramic sound emitter HA1 - 4FE-610-09 from an imported telephone set. You can use domestic ZP-1, ZP-22, HPA22A, etc. When using a domestic microcircuit in the signaling device, a piezoceramic sound emitter can be connected to antiphase UZCH outputs - terminals 5 and 6 DA1.

Unmistakably made of serviceable parts, the device is operational immediately after connecting to the PSU. If the supply voltage is greater than 25 ... 30 V, it is desirable to increase the resistance of the resistor R6 to 1,2. 2,4 kOhm If the signal is too loud, a resistor can be connected in series with the sound emitter.

The device can be easily turned into a PSU overheating sensor. To do this, the upper (according to the diagram) terminal of the resistor R1 is connected to the positive terminal of the capacitor C1, and the resistor R2 is replaced with a thermistor with a negative TKS value of 4,7. 10k0m. The operating threshold of the device is set by selecting the resistor R1.

Literature

Butov A. Short circuit buzzer. - Radio, 2001, No. 10, p. 58.
Butov A. Laboratory switching power supply on the L4960 chip. - Radio, 2011, No. 11, p. 27, 28.

Author: A. Butov

See other articles Section Protection of equipment from emergency operation of the network, uninterruptible power supplies.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Positive thinking strengthens the immune system 17.11.2021

A group of specialists from the University of Exeter and the University of Oxford (UK) concluded that positive thinking helps to strengthen the immune system.

Scientists conducted an experiment involving more than 135 people. They were divided: some of the volunteers listened to audio lectures on the need to develop positive thinking - to perceive life and the people around them more optimistically, kinder and more condescendingly. Another part of the volunteers listened to the arguments about why the attitude to everything should be as critical as possible.

Volunteers from different groups were measured heart rate and sweating - markers of psychological state. As a result, it turned out that the participants from the "positive thinking" group had their lower parameters, that is, they were more relaxed and less anxious. The level of production of anti-inflammatory components of the immune system in their bodies was also lower, which meant that there was no high risk of infection and disease for a person.

At the same time, the participants in the experiment, who listened to the need for a strict attitude to the world around them, demonstrated increased heart rate and increased sweating. According to doctors, such signs appear when there is a feeling of danger and insecurity, increased stress.

"Positive thinking significantly calms the heartbeat and strengthens the immune system, while negative thoughts have a negative impact not only on the psyche, but also on the physical condition of a person. When we learn not to react painfully to external threats, we strengthen our immunity, thereby increasing chances of recovery," the researchers said.

Other interesting news:

▪ Synthetic lift

▪ Espressif ESP32-WROVER WiFi Modules for IoT Voice Applications

▪ SPHEREx telescope

▪ Diamond tells the origin of life

▪ Astronauts will be sent to the captured asteroids

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Sites of amateur radio equipment. Article selection

▪ article Two-story rabbitry. Tips for the home master

▪ Article What sports are considered Olympic? Detailed answer

▪ article Weigher. Standard instruction on labor protection

▪ article Thermometer-prefix to a digital multimeter. Encyclopedia of radio electronics and electrical engineering

▪ article Overcurrent signaling device. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

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