Digital scale with indication correction. Scheme, description

Free technical library

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

Digital scale with indication correction. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Civil radio communications

Comments on the article

The use of digital scales allows, at low cost, to significantly improve the accuracy of the reading devices of transceivers and receivers. One of the simplest options for constructing a digital scale is the option of measuring the frequency of a tunable local oscillator (GLO) [1, 2]. This method is often used in VHF transceivers. Measuring the frequency of the "stand" local oscillator, which carries the generated signal to the operating frequency (144, 430 MHz, etc.), and summing it with the frequency of the GPA and IF, requires high-speed and, therefore, expensive digital microcircuits. But they are not available to everyone. Therefore, often the digital scale provides an indication of only hundreds, tens and units of kilohertz of the GPA frequency.

Indicators displaying units, tens and hundreds of megahertz are controlled by a switch associated with the range switch, but not related to the logic of the digital scale. A certain inconvenience in this case is the need to select the frequency of the "stand" local oscillator such that the beginning of the range, for example, 144,000 MHz, corresponds to zero values of hundreds, tens and units of the GPA frequency. It is often difficult to fulfill this condition due to the inability to purchase quartz resonators for the required frequency. So, for example, on the two-meter range, when using a 10,7 MHz quartz filter and changing the GPA frequency from 11 to 12 MHz, the frequency of the "stand" quartz local oscillator should be 122,3 MHz. On the 70 cm band, its frequency should be 410,3 MHz.

The cardinal solution to this problem is to use a programmable counter on a 561IE11 or 564IE11 chip. This counter allows, when a combination of logical 2 (ground) and logical 4 (+ 8 V) is applied to its inputs Dl, D0, D1, D9, to write a number from 0 to 15 in each bit. At the same time, by supplying 0 or 1 to the input of the "+1" counter, you can add or subtract the recorded number from the measured frequency of the GPA. So, for example, the frequency of the quartz local oscillator in the two-meter range was 121505 kHz for the author. This was achieved by multiplying the oscillations of a quartz resonator with a frequency of 13500 kHz nine times from the set for the UW3DI transceiver (40 m). In this case, the GPA frequency at the beginning of the range (Fd = 144000 kHz) will be:

Fgpd \uXNUMXd Fd - Fkv.g - Fpch

where Fkv.g - the frequency of the quartz local oscillator "stand"; Fp - intermediate frequency. As a result, Fgpd = 144000 - 121505 - 10700 = 11795 kHz.

In order for the indicator to have zeros in place of hundreds, tens and units of kilohertz when tuning to a frequency of 144000 kHz, the number 205 must first be written into the counter. The desired combination is dialed according to the table.

Digital scale with indication correction

Logic 0 corresponds to the shorting of the inputs D1-D8 of the counter to the case, and 1 - to the supply of voltage +9 V to the inputs.

A schematic diagram of the proposed digital scale is shown in the figure. Fragments of the scheme from [2] were used in its development. The scale as a whole is made traditionally, so we will report only its features. The circuit from C6R8 provides, when turned on, the installation of the K176IE4 dividers in the initial state. As switches SA1-SA12 it is very convenient to use small-sized switches VDM1-4 used in computer technology devices. They easily allow you to set the required numbers in the counters DD8-DD10.

The diagram (Fig. 1a) shows the option of connecting the high-order indicators of the 2-meter range. Pin 1 of the indicators is permanently connected to a + 9 V source, and pins 2 or 3 are supplied with + 9 V voltage through a switch, depending on the included 144 or 145 MHz range, respectively.

In the same place (Fig. 1b), with the preservation of the reference designations of the elements, the option of connecting indicators for the 70 cm range (432 or 435 MHz) is shown.

Rice. 1 (а,b) (click to enlarge)

Structurally, the scale is made on a double-sided printed circuit board 150x57 mm in size using hanging conductors (based on the principle described in [1]). The VDM1-4 switches are installed on a separate board above the DD8-DD10 microcircuits and are connected to the last wires. LED indicators HG1-HG6 are conveniently mounted on 50x30mm plates with universal printed wiring and connected to the main board with a flexible cable.

If the GPA frequency does not exceed 14 ... 15 MHz, you can try to reduce the scale supply voltage to 7 V. This will reduce the current consumption to 150 ... 160 mA.

Literature

The best designs of the 31st and 32nd exhibition of radio amateurs. - M.: Ed. DOSMF USSR / VHF transceivers "Graviton 144" and "Graviton - 432", p. 90-101.
Chalyshev L. Amateur connected KV. receiver. - M.: Radio, 1982, N10, p. 17-21.

A. Sablin (UA4FP), Penza

See other articles Section Civil radio communications.

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

Powerful energetic light of the Sun detected 01.08.2023

The most intense light emitted by the Sun has been discovered and studied. This light, known as gamma rays, turned out to be much brighter than expected.

Researchers have found that the sun emits the most powerful gamma rays, with energies up to 10 teraelectronvolts (TeV). This discovery, made using the Cherenkov High Altitude Water Observatory (HAWC) in Mexico, raises new mysteries related to the mechanisms of gamma-ray production and the influence of the solar magnetic fields on this process.

"The sun turned out to be even more amazing than we thought. We thought we understood it well, but it turns out there is a lot that we don't know yet," said Mehr Un Nisa, a research fellow at Michigan State University (MSU).

The Cherenkov High-Altitude Water Observatory in Mexico (HAWC) played a role in the discovery. What sets HAWC apart is its unique approach: instead of traditional optical telescopes, it uses an array of 300 large water tanks, each containing about 200 metric tons of water. The observatory is located at an altitude of 4100 meters above sea level between two extinct volcanoes. This innovative design makes it possible to "observe" the impact of gamma rays on the Earth's atmosphere, creating so-called air showers.

Data from HAWC began to be collected in 2015, and by 2021, scientists have accumulated enough information to analyze solar gamma rays. Even though high-energy radiation does not reach the Earth's surface, gamma rays left characteristic signatures that Nysa and her colleagues discovered. It was found that the energy of gamma rays reaches an astronomical 10 teraelectronvolts - the maximum level.

Already in the 1990s, scientists assumed that the Sun could emit gamma rays, but at that time there were no means to detect them. The first gamma rays with an energy of more than a billion electron volts were detected with the Fermi Gamma-ray Space Telescope in 2011.

Now scientists are setting themselves the task of unraveling the mechanism of the formation of such high-energy gamma rays and determining the role of the Sun's magnetic fields in this phenomenon. This discovery opens up new horizons for future research and may require a revision of our understanding of the Sun and its influence on the Universe.

Other interesting news:

▪ Synaptic transistor that mimics the human brain

▪ Greenland pops up

▪ Anti-oxygen tent

▪ Electricity behaves like water

▪ New ultra-fast DAC

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Digital technology. Article selection

▪ article Grated kalach. Popular expression

▪ article What is a neutron star? Detailed answer

▪ article Academic node. Travel Tips

▪ article Power standards (DIN, RMS, PMPO). Encyclopedia of radio electronics and electrical engineering

▪ article Several cards appear alternately at the top and bottom of the deck. Focus Secret

Leave your comment on this article:

All languages of this page

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