Musical call with automatic change of melody. Encyclopedia of radio electronics and electrical engineering

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

 Comments on the article

In many apartments, a musical bell is used to call the owner. It's not hard to make your own. At the same time, the bell will be in no way inferior to those produced by the industry, but will cost much less.

It is convenient to perform the device on a specialized sound synthesizer chip from the UMS series. These microcircuits are produced with several programmed melodies, which can be switched by applying voltage to the "melody selection" input.

In contrast to the already published versions of musical signaling devices, in the one shown in Fig. 1.24 circuit is not required to use an additional button to switch the melody. The melody changes automatically with each next press of the call button (SB1). Each melody will sound as long as the button is pressed.

Transistor VT2 was used to amplify the audio signal. Resistor R5 allows you to adjust the volume of the audio signal over a wide range.

Matching the output impedance of the circuit with a low resistance of the sound emitter coil is performed using a transformer T2. In addition, the use of a transformer eliminates the flow of direct current through the speaker, which improves its performance.

Any ordinary speaker can be used as a sound emitter BA1. It is allowed to connect several speakers and place them in convenient places in the apartment.

The desired timbre of the sound is adjusted by selecting the capacitor C3 *. This capacitor, together with the primary winding of the transformer T2, forms an oscillatory circuit included in the collector circuit of the transistor VT2. This circuit not only increases the sound volume, but also makes the sound more pleasant. Indeed, rectangular pulses come to control VT2, which contain many high-frequency harmonics, and the transformer and its circuit circuit are a filter.

Since the quality factor of the circuit formed in the VT2 collector circuit is rather low, the BA1 speaker will play all the notes of the melody programmed in the microcircuit.

When you press the SB1 button, power is supplied to the circuit and a melody will sound. Since the UMS8-08 microcircuit has an allowable supply voltage range of 1,33 ... 2 V, a low-voltage voltage regulator is made on the VD1 ... VD4 diodes. After the VD5 diode, the capacitor C1 will have a voltage of 2 V. This voltage on C1 remains for a long time even after the SB1 button is released (even if the G1 battery is not installed). This is explained by the fact that the microcircuit is manufactured using CMOS technology and consumes little in the operating mode, and when the supply voltage drops below 1 V, it goes into a halted state. The current consumption in this mode does not exceed 1 μA. This state remains for quite a long time.

When you press the SB1 button again, voltage is applied using the transistor VT1 to inputs 6 and 13 of the DD1 microcircuit. Since these circuits are combined ("start" - output 6 and "melody selection" - output 13) and are connected through an open transistor VT1 to the power supply circuit of the microcircuit, the SB1 button allows not only to turn on the melody, but also to change it when pressed again.

In standby mode, the device does not consume power from the network, and the G1 battery is optional (may not be installed), but in this case, the time for saving the last selected melody will be limited.

All the parts highlighted in the diagram by a dotted line are located on a printed circuit board 55x55 mm in size, shown in fig. 1.25. It is more convenient to install the DD1 chip on the contact panel, which in the future will allow you to change the set of melodies without resoldering the board, easily replacing only the chip itself.

The VA1 speaker can be of any type with a coil with a resistance of at least 8 ohms and a power of 0.5 ... 1 W, for example 0.5GD-37.

Transformer T1 is taken from the TP series from a network adapter with an output voltage of 6 ... 9 V (current not less than 100 mA). Usually they are used to power household devices and have a housing in the form of a mains plug. If such a transformer has only one secondary winding, then a bridge rectifier will have to be installed to power the circuit.

Transformer T2 - output from any miniature transistor radio.

Transistor VT1 can be replaced with KT315, and VT2 with KT972A (B), KT829A. Diodes VD1 ... VD8 type KD106A, but many others with similar parameters will do.

Adjusting resistor R5 used type PPB-1A, capacitors C1, C2 type K50-35 for 25 V, C- - K10-17. Any type of ZQ1 quartz resonator for an operating frequency of 32768 Hz.

In order for the duration of the melody to not depend on how long the call button is pressed, a timer can be set in the circuit, fig. 1.26. It is made on two transistors VT3, VT4 and relay K1. The timer allows you to increase the execution time of the melody up to 6 ... 7 s after the button is released (the time depends on the value of the capacitor C4).

The timer circuit works as follows. At the initial moment, when the SB1 button is pressed, the relay K1 will turn on, since the transistor VT3 will be in saturation due to the base current passing through the resistor R6. The relay with its group of contacts K1.1 will block the button circuit for a while until C4 is charged. As soon as the voltage at the VT4 base reaches a level at which it opens, this will close the VT3 base circuit to a common wire and the relay will turn off. The contacts of relay K1.1 will open and power will no longer be supplied to the circuit (if the SB1 button is not pressed).

Contact group K1.2 allows you to accelerate the discharge of capacitor C4 when the relay is turned off so that the timer is quickly ready for operation when the call button is pressed again and allows you to increase the duration of the melody. Resistor R8 limits the discharge current C4.

The following details were used in the timer circuit: C4 - tantalum K53-18 or K53-1 for 20 V. Transistor VT3 can be replaced with KT829A (B), and VT4 with KT315B (G, E), KT312V.

Repe K1 is suitable for any (having two groups of switching contacts) with a response voltage of 9 ... 12 V and a switching voltage of 220 V.

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 Cats can heal people 16.10.2016 A group of leading experts implemented a unique experiment of its kind, the result of which showed that cats can really heal people. This information was provided by experts from clinical centers located in the United States of America and Germany. During the implementation of projects, doctors involved more than 10 thousand respondents. It turned out that in three out of four cases, cats prolong the life of their owners. According to experts, this is due to the fact that the temperature of pets is slightly higher than that of people. Thus, cats warm the body of men and women, in addition, their purring is endowed with a therapeutic effect. The researchers said that the vibration that these pets create has a positive effect on the human body. Doctors have recorded that cat owners suffer from heart disease 20% less often than other people. Pet owners live to a ripe old age in 70% of cases. Cats are also useful for children, in particular, ensuring the correct functioning of their immune system. Babies who come into contact with cats are thus protected from allergies.

Other interesting news:

▪ In autistics, the hemispheres of the brain work symmetrically

▪ Water is a source of terahertz radiation

▪ Glowing fingerprints

▪ Future mathematicians compose well

▪ CC3200 - Cortex-M4 microcontroller with built-in WiFi

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the website Experiments in Physics. Selection of articles

▪ article Pass like a red thread. Popular expression

▪ article Why do some people have nice voices? Detailed answer

▪ article bird cherry. Legends, cultivation, methods of application

▪ article Fundamental problems of the development of electric power industry based on renewable energy sources in Russia. Encyclopedia of radio electronics and electrical engineering

▪ article The method of restoration of permanent magnets. Encyclopedia of radio electronics and electrical engineering

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