Encyclopedia of radio electronics and electrical engineering / Civil radio communications

 Comments on the article

Local oscillators and master oscillators of modern receivers and amateur radio transceivers today are all made on the basis of frequency synthesizers with microcontroller control. However, tuning such a receiver to the station by typing the frequency value on the keyboard is very inconvenient, and for smooth tuning (more precisely, discrete with a very small step, imitating a conventional analog one), an accurate converter of the angle of rotation of the tuning knob into a digital code is needed - the so-called encoder. The cost of this precision device often exceeds the price of all other parts of the synthesizer combined. Nevertheless, a radio amateur from Germany (Steffen Braun, DJ5AM) managed to make a simple and cheap, but quite suitable for amateur use, encoder from the parts of a faulty computer mouse [1].

The rotational movement of the computer mouse ball inside it is perceived by two optoelectronic rotation angle sensors. The pulses generated by them enter the computer, are processed by it and control the movement of the cursor relative to the X and Y axes of the monitor screen. The basic principle - the conversion of the angle of rotation into the number of pulses is quite suitable for the encoder, in addition, each of the "mouse" sensors is equipped with two appropriately located sensitive elements, which allows you to determine not only the angle, but also the direction of rotation. You can read more about the design and operation of these sensors in [2].

Getting started, it is necessary to open the body of the "mouse" and make sure that the plastic bearing, in which the sensor shaft rotates, is between the thickened part of the shaft in contact with the rubberized ball and the slotted disk. For many "mice" this is not the case - the shaft is fixed in two bearings located at its ends. This design is not suitable for our purposes. The thickened part (head) of the shaft, approximately 4 mm in diameter, must be long enough to accommodate the tuning knob. The distance from the head to the disc must be at least 15 mm.

Parts of one of the two sensors present in it are removed from the "mouse": a disk with slots and its shaft together with a plastic bushing-bearing, a part of the printed circuit board with two optocouplers is cut out with a jigsaw (each of them is an infrared emitting diode opposite each other and a phototransistor that perceives its radiation). The necessary details are shown in fig. 1, you can not worry about the safety of the rest.

To mount the encoder to the front panel of the receiver or transceiver, one more part is required - an aluminum sleeve with an external thread and a nut from a variable resistor. The sensor shaft is passed through the bushing hole. It is possible that to perform this operation, the plastic bearing in which the shaft rotates will have to be filed, and the aluminum sleeve shortened so that the tuning knob can be placed on the shaft head protruding from it.

You should not solder optocouplers from the printed circuit board of the "mouse" so as not to damage them. The part separated from the board with optocouplers is glued with epoxy glue or in another way to the bearing sleeve so that the optocouplers take their previous position relative to the disk. Before the final hardening of the klya, you should make sure that the disk rotates easily.

Emitting diodes and "mouse" phototransistors are outwardly very similar. You can tell them apart by tracing the printed conductors on the board. Emitters are usually connected in series. This circuit must be saved and connected through a quenching resistor to a power source. The resistor value is chosen based on the current through the diodes is not more than 5 mA. Most often, 1 kΩ is suitable.

Next, the outputs of an ohmmeter set to a measurement limit of 100 kΩ are connected to the collector and emitter of one of the phototransistors and, slowly rotating the disk, make sure that the readings of the device decrease sharply each time the phototransistor is illuminated by an emitting diode through a slot in the disk. If this is not the case, it is possible that the collector and emitter leads are not defined correctly and the polarity of the ohmmeter connected to them needs to be changed. Too bright external lighting can also affect the result, so work should be done in the shade. In the same way, the phototransistor of the second optocoupler is checked.

The scheme of the electronic part of the valcoder is shown in fig. 2.

Chips DD1 and DD2 have domestic counterparts: 4093 - K561TL1, 4013 - K561TM2. The pulses from the collectors of the phototransistors BL1, BL2 are fed to the inputs of the shapers - Schmitt triggers DD1.1 and DD1.2 and further - to the inputs C and D of the trigger DD2.1. Since, depending on the direction of rotation of the shaft, the sequence of arrival of pulses at the inputs of the trigger changes, the latter is set to one of two stable states. The correspondence between the logic level at the output of the trigger and the direction of rotation is determined experimentally. The pulses from the output of the element DD1.1 serve as counting - their number is proportional to the angle of rotation of the shaft.

Microcircuits DD1, DD2 and other elements are connected according to the scheme with rigid wires and leads, the entire assembly is glued to the mechanical units of the encoder. The appearance of this structure is shown in Fig. 3.

If the encoder will serve as part of a more complex product, the DD1 and DD2 microcircuits can be installed on its printed circuit board.

Literature

1. Braun S. "Aus die Maus": Inkrementale Drehgeber - einfach realisiert. - Funkamateur, 2002, No. 4, S. 362, 363.
2. Long A. "Mouse": What's inside and what it eats. - Radio, 1996, No. 9, p. 28-30.

Author: Steffen Braun, DJ5AM

See other articles Section Civil radio communications.

Read and write useful comments on this article.

<< Back

<< Back

Latest news of science and technology, new electronics:

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 ... >>

Primium Seneca keyboard 05.05.2024

Keyboards are an integral part of our daily computer work. However, one of the main problems that users face is noise, especially in the case of premium models. But with the new Seneca keyboard from Norbauer & Co, that may change. Seneca is not just a keyboard, it is the result of five years of development work to create the ideal device. Every aspect of this keyboard, from acoustic properties to mechanical characteristics, has been carefully considered and balanced. One of the key features of Seneca is its silent stabilizers, which solve the noise problem common to many keyboards. In addition, the keyboard supports various key widths, making it convenient for any user. Although Seneca is not yet available for purchase, it is scheduled for release in late summer. Norbauer & Co's Seneca represents new standards in keyboard design. Her ... >>

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Random news from the Archive With a screen on the chest 02.11.2007 The Dutch firm Philips has created a thin and flexible television screen based on organic light emitting diodes. So far, all the problems associated with accurate color reproduction and durability of light-emitting elements have not been resolved, but in three years, as the Dutch promise, on the basis of this invention it will be possible to produce not only TVs and computer monitors glued to the wall, but also T-shirts with a demonstration of moving images and phrases . True, it is not yet known whether it will be possible to wash such a T-shirt.

Other interesting news:

▪ All sea salt is contaminated with plastic

▪ Neurocomputer interface implanted in human

▪ Philips budget LED lamps

▪ Toshiba Medium Voltage Photo Switch for Industrial Applications

▪ Micron 9300 Solid State Drives

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Microcontrollers. Article selection

▪ article Versta Kolomna. Popular expression

▪ article What is the Decameron? Detailed answer

▪ article Three-leaf watch. Legends, cultivation, methods of application

▪ article Biomass as a constantly renewable source of fuel. Encyclopedia of radio electronics and electrical engineering

▪ article Soaring vase. 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