Radiotelephone interface for simplex radios. Scheme, description

Free technical library

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

Radiotelephone interface for simplex radios. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Telephony

Comments on the article

The proposed scheme (Fig. 1) allows the use of simplex radio stations (without modifications) for communication between a telephone subscriber and a radio subscriber. The telephone subscriber has priority. The communication range between the base radio station and the mobile one is determined by the base output power and is 30...50 km.

The interface is assembled on digital and analog elements. Let the telephone caller dial the number. The ringing signal from the L1-L2 line is fed through the VD7 bridge to the short-circuit calling relay, which is triggered for 3 s (the duration of the pause between calls) and closes contacts K3.1.

At the same time, the ringing signal is fed through the isolating transformer T1 to the microphone input of the base radio station and to the input of the electronic time relay of the telephone subscriber. The key on VT5 is opened and the radio goes into transmission mode. The ringing signal is emitted by the radio base station.

After receiving the ringing signal, the radio subscriber (in pause) presses the PTT "Transmit" and answers the call. At the time of arrival of a response from the radio subscriber, the signal from the speaker of the base radio through the closed contact K3.1 is fed to the electronic relay of the radio subscriber. Relay K1 is activated and contact K1.1 switches the output of the radio station (Gr) to winding II of transformer T1.

Fig.1. Schematic diagram (click to enlarge)

At the same time, the logical "1" from the output of the element DD1.2, through the diode VD3, causes the electronic relay to operate on DD3.1, DD3.2 and switches K2. Contacts K2.1 close the telephone line through the resistor R18, which is equivalent to the "Off-hook" mode. Contacts K2.2 are connected in parallel with K3.1.

At the same time, an electronic relay is activated on DD4.1, DD4.2 and turns on K4, which, with its contacts K4.1, K4.2, connects the primary winding of the transformer T1 to the telephone line. The telephone subscriber hears the answer of the radio subscriber. When the radio subscriber finishes speaking, relay K1 releases. Its K1.1 contacts connect the II T1 winding to the microphone input of the radio base station. The telephone caller starts talking. Through an electronic relay on DD2.1, DD2.2, VT5 opens, and the radio goes into transmission. In the future, the conversation between subscribers is carried out in turn. Each subscriber is a logical "1." from the output of its electronic relay, it supports the K1.2 relay ("Hook up") on (via DD2.2, DD2).

10 seconds after the end of the conversation, relay K2 is turned off, which is equivalent to the "On-hook" mode. In the radio station, beeps are heard. After 20 s, the linear relay K4 is activated, and the line is disconnected. The interface goes into standby mode.

Interface operating modes are indicated by corresponding LEDs.

Details and design. The interface is developed on a public element base. Chips DD1 ... DD4 - K561LA7, transistors VT1 ... VT6 - KT3102. It is desirable to select VT1 and VT3 with a large gain (letters G, E). All diodes - KD503, KD521, KD522, LEDs - AL307. Resistors - OMLT-0,125, 0,25. Relays - small-sized: K1 - RES15 (003, 004), K2 ... K4 - RES60 (0001) or two RES15 relays in parallel.

T1 - matching transformer from small radio receivers. Winding resistance-30 ... 200 Ohm. The ratio of winding turns is 1:2.

The circuit is assembled on a board made of foil fiberglass with a thickness of 1,5 ... 2 mm. The dimensions of the board are determined by the dimensions of the components. The author made the board by cutting 5x5 mm squares (with a cutter made from a hacksaw blade). The overall size of the board is 150x150 mm.

Establishment comes down to setting the time intervals for holding electronic relays. For subscriber relays (DD1.1, DD1.2 and DD2.1, DD2.2) - 1 ... 2 s, "Off-hook" relay (DD3.1, DD3.2) - 5 ... 20 s, line relay (DD4.1, DD4.2) - 10...30 s. With serviceable parts, the circuit starts working immediately. At the radio station (base), the volume level knob must be set to the middle position, the "ShP" (squelch) knob is removed until the noise disappears completely (with a small margin). In principle, opening the squelch in standby mode against strong impulse and radio interference will not lead to the capture of the radio channel, because. before that, relays K2 and short circuit did not work. Thus, the interface is protected from unauthorized access by the radio link.

The interface is connected to the base radio station by a five-pin connector from household equipment connected in parallel with the PTT (or instead of it). The line (L1-L2) is connected in parallel to the home telephone set.

Leaving, for example, to the country house, turn on the power switch S1 and line S2. At the same time, the indicators "Off-hook" (HL2), "Line on" (HL5), "Calling a telephone subscriber" (HL4) turn on. After 10 ... 20 s, all indicators go out - the standby mode begins.

Good luck building and see you soon! 73!

See other articles Section Telephony.

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

Intel Xeon D-2100 Processors 07.02.2018

Intel introduced the Intel Xeon D-2100 system-on-a-chip processor, designed to meet the needs of edge devices, as well as data centers and network applications with limited space and power consumption.

The Intel Xeon Processor D-2100 further enhances record-breaking efficiency and extends the innovative capabilities of the Intel Xeon Scalable platform from the data center to the network edge and web application layer, where network operators and cloud service providers face the need to continuously increase performance without increasing consumption. electricity.

The novelty will provide higher performance and hardware-based edge protection technologies needed to meet the growing demand for increased computing power, more processing capabilities and data protection closer to the end devices. For example, it will help communication service providers (CoSPs) implement multiple access edge computing (MEC), which will allow software applications to access local content and real-time information about local access network conditions, reducing congestion, preventing mobile network congestion and opening new applications of the technology in cars with 5G connectivity, smart stadiums, retail and healthcare.

The new processors will also enable telecom service providers to deliver network services with higher bandwidth, optimized workload and lower power consumption to customer equipment using virtualization (vCPE), such as virtual private networks and encryption services.

The Intel Xeon D-2100 processors include up to 18 "Skylake-server" generation Intel Xeon cores, as well as integrated Intel QuickAssist technology that supports cryptographic functions, encryption and decryption at speeds up to 100 Gb/s. In addition to these data protection enhancements, the new product will be supported by system software updates to protect consumers from vulnerabilities such as Specter and Meltdown.

Other interesting news:

▪ 12W LED Drivers from TDK-Lambda

▪ Plastic that decomposes in soil in six weeks

▪ entomology passing through

▪ New rover tested

▪ The popularity of LCD TVs is growing

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Firmware. Article selection

▪ article Goof off. Popular expression

▪ article How did the mountains appear? Detailed answer

▪ article Buten fragrant. Legends, cultivation, methods of application

▪ article Universal indicator. Encyclopedia of radio electronics and electrical engineering

▪ article Standards for testing electrical equipment and devices for electrical installations of consumers. Test voltages of industrial frequency of isolation of semiconductor converters. 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