Two-signal power indicator. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur

 Comments on the article

Many foreign products are accompanied by an advertising formula for the multifunctionality of products such as "two in one", "eight in one", etc. This approach to functionality is also applicable in amateur design.

For example, when powering household equipment from batteries, in addition to indicating the on state, it is also necessary to indicate the discharge of the batteries (two functions in one indicator). In this case, it is most convenient to use a two-color LED - the presence of a glow indicates the device is turned on, and the transition of the color of the glow from green to red indicates a discharge of the battery.

On fig. 1 shows a simple version of such an indicator. Transistors VT1 and VT2 form a Schmitt trigger, the switching threshold of which depends on the voltage at the red LED (pins 2, 1) and the ratio of the resistances of resistors R1 and R2. At a high voltage level, transistors VT1, VT3 are open, and transistor VT2 is closed and the green LED is lit (pins 3, 1). The total current through the resistor R3 and the base current of the transistor VT3 flows through the red LED, but it is negligible and practically unable to light the LED. At a low voltage level, transistors VT1 and VT3 are closed, and transistor VT2 is open. The red LED is lit.

The brightness of the indicator is set by selecting the resistor R4. The hysteresis (color change zone) of the indicator is about 0,3 V, and the desired color transition voltage is specified when setting by selecting resistors R1, R2. To simplify the setting, the constant resistor R2 can be replaced with a trimmer, which, however, will increase the dimensions of the indicator. A slightly larger voltage drop on the green LED compared to the red LED is not significant, since the saturation voltage of the collector-emitter of transistors is less than the saturation voltage of the base-emitter.

A slight complication of the device (Fig. 2) makes it possible to reduce the hysteresis to 0,1 V and increase the efficiency of the indication when the supply voltage changes. Here, the HL1 indicator LEDs are fed with a stable current (about 1,5 ... 2 mA) from the VT4 field effect transistor, and the threshold voltage is removed from the stabistor, which is the HL2 LED. The brightness of the indication depends on the drain current of the field-effect transistor, so it is set by selecting the transistor of the desired group.

In this version, the indicator is operable in a wide range of supply voltage (5...15 V and more) without changing the ratings of parts. It is only necessary to set the required color transition voltage by changing the ratio of resistors R1 and R2.

The efficiency of the LED indicator decreases with increasing brightness. Often, when choosing low currents through the LED, its brightness is insufficient. To increase the brightness of the indication while reducing the current consumption (three qualities in one indicator) allows the pulse mode of operation used in the device, assembled according to the one shown in Fig. 3 scheme.

Transistors VT5, VT6 form a multivibrator with a large duty cycle, the indication occurs at the moment of the open state of the transistors. The desired flash frequency depends on the parameters of the R5C1 chain and is set by choosing the capacitance of the capacitor, and the flash duration depends on the parameters of the R4C1 chain and is set by changing the resistance of the resistor (with the indicated values ​​​​of the elements - approximately 1 Hz and 0,2 s). The increased brightness is due to the choice of the VT4 transistor with an increased drain current (7 ... 10 mA), and the efficiency is ensured by the duty cycle, which lowers the average value of the current consumed.

The ALC1A assembly, consisting of two LEDs in one housing, was used as the HL331 indicator. The HL2 LED can be of any visible glow and with low brightness, since it is included as a zener diode. However, with a small indicated voltage, this LED should be selected with a small voltage drop at the operating current of the indicator. Resistors - MLT-0,125, it is better to use a small-sized capacitor C1 - KM-6 or K10-7, but you can also use film (K73-17, etc.). To obtain a small hysteresis, it is necessary to use transistors VT1, VT2 with a high transfer coefficient and low saturation voltage - from the KT502 and KT503, KT3102 and KT3107 series, and in place of VT3 - also from the KT209 series.

If, when the green LED is lit, a noticeable red glow is observed, then the VT3 transistor will have to be replaced with another one with a higher transmission coefficient, or the red LED should be shunted with a resistor (with a resistance of about 5,1 kOhm). Transistor VT6 must allow reverse base-emitter voltage not lower than the indicator supply voltage. The field-effect transistor of the KP303 series can be replaced with a transistor of the KP302 or KP103 series (in the latter case, the supply voltage is not more than 12 V, and the drain and gate connection with the source is reversed). Due to the spread of the normalized drain current, it is desirable to measure its actual value before installing the sample in the device.

When setting up the device, the supply voltage is changed and the voltage of the glow color transition is determined (best with a digital voltmeter). It should correspond to a battery discharge voltage of 1 V per nickel-cadmium battery.

Author: V. Zhgulev, Serpukhov, Moscow region

See other articles Section Beginner radio amateur.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Wireless speaker Samsung Music Frame HW-LS60D 06.05.2024

In the world of modern audio technology, manufacturers strive not only for impeccable sound quality, but also for combining functionality with aesthetics. One of the latest innovative steps in this direction is the new Samsung Music Frame HW-LS60D wireless speaker system, presented at the 2024 World of Samsung event. The Samsung HW-LS60D is more than just a speaker system, it's the art of frame-style sound. The combination of a 6-speaker system with Dolby Atmos support and a stylish photo frame design makes this product the perfect addition to any interior. The new Samsung Music Frame features advanced technologies including Adaptive Audio that delivers clear dialogue at any volume level, and automatic room optimization for rich audio reproduction. With support for Spotify, Tidal Hi-Fi and Bluetooth 5.2 connections, as well as smart assistant integration, this speaker is ready to satisfy your ... >>

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Random news from the Archive 128-layer 3D NAND Flash 16.04.2020 China's Yangtze Memory Technologies Co (YMTC) has unveiled a milestone product: 128-layer NAND flash memory. The X2-6070 series of chips uses proprietary XTracking 2.0 multi-layer memory architecture. It should be noted that the immediate predecessor of this memory is a 64-layer chip based on the XTracking 1.0 architecture, which entered mass production in September 2019. Most other flash memory manufacturers, including Samsung, SK Hynix and Micron, after 64-layer memory, first switched to the production of 96-layer memory and only introduced 128-layer products only last summer. As planned, YMTC managed to skip this step. According to the manufacturer, the new memory will first find use in consumer-grade solid-state drives, and then come to drives for servers and corporate storage. YMTC is part of the state-owned conglomerate Tsinghua Unigroup and is one of dozens of participants in a program to localize advanced electronic technologies and reduce dependence on imports.

Other interesting news:

▪ Pure Digital FlipVideo Camcorder

▪ Sony PlayStation Portable 2

▪ Organic molecules found on Mars

▪ immune switch gene

▪ Neural efficiency as a characteristic of the level of intelligence

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the Radio Control website. Article selection

▪ article From here, if you ride for three years, you won’t get to any state. Popular expression

▪ article In which country did a cat work as a stationmaster and attract many new clients? Detailed answer

▪ Verbeinik's article. Legends, cultivation, methods of application

▪ article Knots of amateur radio equipment. Filters and matching devices. Directory

▪ article The simplest model of a wind turbine. physical experiment

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