Musical house bell. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Calls and audio simulators

 Comments on the article

Now no one is surprised if, when you press the bell button located at the front door of the apartment, instead of the usual "tr ... r" or "ding-dong", a fragment of a popular piece of music or the voices of animals and birds is heard. On the shelves of stores selling consumer electronics, there are many options for domestic and foreign musical calls, which are often even cheaper than conventional electromechanical ones. Most domestic calls are built on the basis of microcircuits of the UMS-7 or UMS-8 series, included in an almost typical scheme. In amateur radio literature, the shortcomings of a typical circuit have been repeatedly described (a sharp sound caused by the pulsed nature of the output signal, when the start button is briefly pressed, the first melody does not sound completely, etc.) and improved versions of the switching circuit were proposed (L.1, L. 2).

Figure 1 in the text shows a diagram of another variant of such a call.

Ris.1

The difference from the typical one is that the sound has become calmer and softer, and with a short press on the "CALL" button, the device plays the entire piece of music. The sharpness of the sound of the bell, included according to the typical circuit, is caused by the fact that the dynamic head, included in the collector circuit of the output transistor switch, receives unipolar rectangular current pulses. Moreover, such a signal is rich in high-frequency harmonics, which, entering into resonance with the speaker coil and its mechanical system, as well as acoustic design, give the musical fragment an uncharacteristic coloring. In addition, the current flowing through the voice coil of the speaker contains a constant component, which shifts the cone and reduces the volume of the sound.

In the intervals between different sections of the musical fragment, loud and sharp clicks appear, caused by the difference in this constant component.

In addition, the operation of the transistor in the key pulse mode for a low-resistance load leads to the fact that the resistance of the transistor in saturation mode turns out to be much higher than that of the voice coil of the dynamic head. Therefore, a significant part of the energy is spent on heating the transistor, and not on the buildup of the diffuser.

These shortcomings can be eliminated if the speaker is connected to the output of the transistor stage through a matching transformer having a high-resistance primary winding and a low-resistance secondary. In addition, by including a capacitor in parallel with the primary winding, we get an oscillatory circuit tuned to the average frequency of musical fragments. The presence of a transformer matches the low-resistance speaker coil to the relatively high-resistance output of the key, and the presence of a resonant circuit smoothes the square-wave pulses, making them closer to sinusoidal and suppresses unnecessary high-frequency harmonics. Since the quality factor of the circuit is not high, all the notes included in the jukebox are played.

The presence of resonance in the circuit leads to the fact that the voltage on the primary winding of the transformer is slightly higher than the supply voltage of the microcircuit, and this leads to an increase in sound volume.

The second defect of the typical scheme is that when the "CALL" button is pressed for a short time, the melody does not sound to the end. The fact is that the sound time in this case is determined not by the duration of the musical fragment, but by the capacitance of the capacitor blocking the start button. In the circuit shown in Figure 1, from the inverse output of the microcircuit (pin 14), the detector receives pulses through C1 to VD1 and VD2, so there will be a unit at the 13th output of the microcircuit all the time while the musical fragment is playing.

The musical bell is powered by a transformerless power source on a D8 rectifier and a parametric stabilizer, consisting of a chain of VD4-VD7 diodes, on which 2-2,5V falls together and a damping reactance of capacitor C4. Capacitor C2 smooths out the ripple of the received direct current.

As a basis for the call, the broadcasting subscriber loudspeaker "Etude" is used. It has a plastic case, speaker and transformer. All this is used in the design, except for the volume control, which is excluded.

Most of the details of the bell are located on a small-sized printed circuit board, the drawing and wiring diagram of which is given in the text.

Ris.2

The board is made of getinaks with one-sided foil. You can use other foil insulating material used for printed circuit boards. The board does not contain buttons S1 and S2 (SK1 is displayed on the front door) and a transformer.

The microcircuit can be UMS-8 or UMS-7, additional numbers (for example UMS-8-08) indicate the musical repertoire of the microcircuit. Buttons S1 and S2 are located on the body of the bell, with the help of the S1 button you can select a melody for further playback, and with the S2 button you can stop playback.

Capacitors C3 and C4 are each made up of two 0,33 uF capacitors connected in parallel, they are marked on the wiring diagram as C3' C3" and C4' C4".

The KTs405A rectifier bridge can be replaced with a bridge assembled from KD105V or KD209V, D226 diodes.

In the absence of a ready-made base, you can use a transformer from the output stage of an old transistor receiver and any 0,1-3 W speaker.

Establishing a properly assembled device from serviceable parts consists in selecting the value of the capacitor C1 in such a way that when you press SK1, a complete one-time playback of a musical fragment occurs. If the capacity of C1 is too large, the machine can play the melody several times in a row. If necessary, you can choose more precisely the capacitance of C3, so that the timbre and volume of the sound are optimal.

Literature

1. On microcircuits of the UMS series. Radio 12-1995, pp. 40-41.
2. Melodious apartment calls. Radioconstructor 11-99, pp. 24-25.

Author: Karavkin V.; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Calls and audio simulators.

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 Photoshop for smartphones 08.03.2013 Adobe Systems announced on its blog the release of the Photoshop Touch app for smartphones. It can be downloaded from the Apple App Store for iOS devices and Google Play for Android devices. The app costs $4,99. The smartphone version of Photoshop has almost the same functionality as Photoshop for tablets, released in October 2011. The smartphone version of Photoshop Touch supports working with layers, there are area selection tools, image adjustments and filters - all key features of the desktop program. Additional features are present, such as Scribble Selection, which allows you to select areas on the image with the touch of a finger.

Other interesting news:

▪ On the benefits of family scandals

▪ Capacitors for vehicles with hybrid start

▪ Programmable Signal Generator LTC6903/6904

▪ Smartphones Poco X5 Pro

▪ Robots play in the sand

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Indicators, sensors, detectors. Article selection

▪ article Fingers in ulcers to invest. Popular expression

▪ article What family, a century apart, were the mistresses of the Princes of Wales? Detailed answer

▪ Article Chastukha common. Legends, cultivation, methods of application

▪ article Sweep frequency generator. Encyclopedia of radio electronics and electrical engineering

▪ article Overturning bottles. 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