Sawtooth voltage generator on a 555 timer. Scheme, description

Free technical library

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

Sawtooth voltage generator on a 555 timer. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Radio amateur designer

Comments on the article

A sawtooth signal can be formed in many ways, one of the most popular ways is to charge a capacitor with a stable current. In this case, the voltage on the capacitor will increase linearly, and if the capacitor is completely discharged when the maximum voltage is reached on it, then a sawtooth signal will be generated. In essence, the circuit is an ordinary relaxation oscillator.

Typically, to implement such a generator, a thyristor or its analogue on bipolar transistors is used. But you can use an alternative method by using the integrated timer 555 (KR1006VI1). A diagram of such a sawtooth voltage generator is shown in Fig. 1. It consists of a stable current source made on a transistor VT1 and a zener diode D1, and a discharge control unit made on a 555 integrated timer chip (KR1006VI1) and diode D2.

Rice. 1. Schematic diagram of a sawtooth voltage generator on a 555 timer (KR1006VI1)

Output 3 of the timer is connected to input 5 through diode D2, which allows the voltage on the internal divider to be reduced to zero if there is a low level signal at the output of the timer. This configuration allows almost complete discharge of the capacitor C1. As soon as the capacitor is discharged to a certain minimum voltage, the timer switches and the capacitor starts charging from the current source, and then the process is repeated cyclically.

The oscillation frequency of the sawtooth voltage generator depends on the capacitance of the capacitor C1 and the resistance of the resistor R1. The frequency is determined by the formula

F=0,4/R1C1. With the ratings indicated on the diagram, it will be approximately 4 kHz.

The current flowing through the resistor R1 must be small, since in the process of discharging the capacitor, the output of the current source closes to ground. This current is calculated by the formula

I=(VD1-Vbe)/R1,

where VD1 is the stabilization voltage of the zener diode D1 (in this case 4,7V) and Vbe is the forward voltage at the base-emitter junction of the transistor VT1 (0,7V). To obtain a good waveform, the current flowing through the resistor R1 should not exceed 20 mA.

As a transistor VT1, you can use almost any low-power low-frequency pnp transistor, for example, KT502. Zener diode D1 - any with a stabilization voltage of 4,7 volts. If you use a zener diode for a voltage of 2,7 volts, then the supply voltage of the circuit can be reduced to 5V. Diode D2 - any silicon, for example, kd503, kd 509.

See other articles Section Radio amateur designer.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

ZL50233/4/5 - echo suppressor chip 22.02.2003

The new ZL50233/4/5 echo canceller IC from ZARLINK SEMICONDUCTOR provides up to 64ms echo cancellation on 4, 8 and 16 channels, respectively.

The chips can also be configured for echo cancellation up to 128 ms. Chips allow for excellent quality of the voice signal, free from echoes, clicks and other types of interference.

Other interesting news:

▪ Clean air helps you think

▪ Keychron Q1 HE Wireless Keyboard

▪ phone on hydrogen

▪ Camera Pentax Q

▪ hypoallergenic poplar

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Mobile communications. Article selection

▪ article Organization Theory. Crib

▪ article Where is the Boeing liner parked, where you can rent a room? Detailed answer

▪ Ferul's article is harsh. Legends, cultivation, methods of application

▪ article Incandescent lamp protection device. Encyclopedia of radio electronics and electrical engineering

▪ article Stick in the nose! Nose stick! Focus Secret

Leave your comment on this article:

All languages of this page

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