Wiper control unit 1. Scheme, description

Free technical library

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

Wiper control unit. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Automobile. Electronic devices

Comments on the article

Many older cars have a simple windshield wiper speed control (two positions - "fast / slow"). The proposed block is more convenient in work. It ensures continuous operation of the wiper for 1 ... 4 s (1 ... 3 brush cycles). The pause between cycles can be adjusted from 0 to 20 with a variable resistor mounted on the front panel. A similar block is described in [1], but it has a significant drawback - depending on the on-board voltage of the car, the time intervals of the device change noticeably. The proposed device is devoid of this drawback and contains fewer parts.

Consider the operation of the block (Fig. 1). The time-setting node is assembled on the DA1 timer. The capabilities of this IC are described in [2]. The timer generates a pulse signal with adjustable pulse duration trimming resistor R1 (wiper motor running) and pause - variable resistor R2 (wiper motor not running).

Wiper control unit
Ris.1

When the unit is turned on with a standard switch on the dashboard of the car, C3 starts charging through R1, VD1 and R2. Immediately after the supply voltage is applied, a high voltage level is set at the output of the DA1 timer. Transistor VT1 opens and the power supply circuit of the wiper motor is closed. The internal circuit of the timer is designed so that after charging the capacitor C2 to 2/3 Up, the voltage at the output of the timer decreases to almost zero, and the transistor VT1 closes. The motor stops after the brushes return to their original state.

Pin 7 of the timer is the open collector output of the transistor. Resistor R3 is the load of this transistor. Its emitter is connected to ground. When the timer switches, a positive signal comes from the internal trigger of the IC to the base of this npn transistor, and it turns on. As a result, at point A, the voltage is close to zero. Capacitor C2 begins to discharge through R2, VD2 and the transistor of the microcircuit. When the voltage on the capacitor drops to 1/3 of the supply voltage, the timer switches back to the single state on the output (pin 3), and the internal transistor closes. Capacitor C2 starts charging again.

The power supply of the timer and timing circuits is stabilized by the DA2 chip so that the time parameters of the unit do not depend on the vehicle's on-board voltage. Capacitors C1, C4 ensure the normal operation of this IC, preventing its self-excitation. Capacitor C3 reduces the effect of interference on the duration of the generated pulses. Diode VD3 is necessary to protect the transistor VT1 from the self-induction EMF of the motor winding that occurs when it is switched. Resistor R4 sets the base current of the transistor VT1 at 50...70 mA. The load capacity of the output 3 of the IC DA1 is 100 mA, so that in the absence of a composite transistor VT1 it can be replaced by an electromagnetic relay. In this case, the VD3 diode is not needed.

Details

Transistor VT1 can be with any letter index. Diodes VD1, VD2 - any silicon small-sized. The VD3 diode can be taken from the KD213, KD2999, KD2997 series with any letter index. Capacitor C2 - preferably from the K52, K53 series. These are durable capacitors with low leakage currents, but since they usually have small capacitances, capacitor C2 can be made up of two, including them in parallel. The remaining capacitors are any small-sized ceramic ones. Fixed resistors - types C2-33, MLT; variable - SPZ-30a, tuning SPZ-386 or SPZ-38d.

Design

The block is assembled on a printed circuit board made of one-sided foil fiberglass. The location of the parts and the drawing of the board are shown in Fig. 2 and 3. The printed circuit board has 4 mounting holes and holes for fixing the wires coming to the control unit. It is recommended to make the wires from the block 7 cm long, strip them to a length of about 2 cm, and then connect them to the standard car wires by twisting them with subsequent insulation. Diode VD3 must be placed above the transistor VT1 with the insulating side of its body to the transistor.

Wiper control unit
Ris.2

Wiper control unit
Ris.3

The device is installed on the car under the dashboard. After that, the trimmer resistor R1 sets the number of brush cycles from 1 to 3.

Literature

1. Oleinik P. Integral timer in the wiper control unit. - Radio, 1988, N12, p.25.
2. Gutnikov VS Integrated electronics in measuring devices. - L .: Energoatomizdat, 1988.

Author: A. Rudenko, Kharkov; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Automobile. Electronic devices.

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

Ash cleans the water 07.01.2015

An interesting use for the ash left from smoked cigarettes came up with researchers from the Institute of Plasma Physics of the Academy of Sciences of the People's Republic of China, led by Li Jiaxing. Taking advantage of the fact that the ashes are very porous, they decided to prepare a sorbent from it to remove arsenic from drinking water. Scientists collected the contents of institute ashtrays, separated carbon from soluble salts and used it as a template to create an openwork structure - they covered it with a layer of aluminum oxide.

Water brought from the province of Inner Mongolia was passed through the resulting material, with an arsenic concentration of 233 µg/l. At the exit, the water turned out to be the purest - there was only 8 μg / l of arsenic in it, which is less than it should be according to the WHO standard. The sorbent showed itself best of all, where the weight of aluminum oxide was twice that of carbon, and the consumption of the sorbent was 4-8 grams per liter.

According to the authors of the work, the ashes can be easily collected in specially designated smoking areas and in this way turn waste into something useful with minimal resources. Water treatment systems operate in large cities, and in small villages it will be possible to clean water with such ash filters.

Other interesting news:

▪ Alternative energy for the space station

▪ Coffee with milk acts as an anti-inflammatory

▪ The robot fuels the spacecraft

▪ Tiny satellites to track global storms

▪ Lamp on bioluminescent bacteria

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Consumer Electronics. Selection of articles

▪ article Soil, its pollution and consequences. Basics of safe life

▪ article Are earthworms useful? Detailed answer

▪ article Loading and unloading of viscous oil products. Standard instruction on labor protection

▪ article Microsecond photocurrent integrator with a phase delay interruption of integration. Encyclopedia of radio electronics and electrical engineering