Overspeed signaling device. Scheme, description

Free technical library

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

Overspeed signaling device. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Automobile. Speedometers and tachometers

Comments on the article

In the magazine "Radio", 1983, No. 9 on p. 28 in the article B. Shirokov describes a digital tachometer designed to measure the speed of the crankshaft of a car engine. A relatively simple attachment to this on-board tachometer, described below, allows you to use it at the same time to monitor compliance with the vehicle's speed limit.

Depending on the requirements of road signs, the driver presses one of the buttons for selecting the maximum allowable speed displayed on the front panel. As soon as the selected speed value is exceeded, a flashing red light signal and an intermittent sound signal will turn on on the instrument panel. Signaling continues until the speed is reduced to the allowed value or until another button is pressed corresponding to a higher speed limit. Thus, the driver is freed from the need to constantly monitor the speedometer readings and will be able to pay more attention to the traffic situation.

The device has five buttons corresponding to the limits of 40, 50, 60, 70 and 90 km/h. The alarm is activated when the speed limit is exceeded by 0,5...2,3 km/h. The warning light only works when the vehicle is in direct gear. The current consumed from the on-board network does not exceed 25 ... 30 mA.

The improvement of the tachometer is to add a decoder to it, an alarm trigger and the alarm device itself.

(click to enlarge)

The decoder (see diagram) is assembled on microcircuits DD1, DD2 and is designed to decipher numbers 1,6; 2,4; 2,8; 3,5, corresponding to the values of the speed of 40,8; 51,5; 61,3; 71,5 and 89,8 km/h. When the output of the counters D2, D5 tachometer BCD. corresponding to any of these numbers, a voltage with a logic level of 1.1 will appear at the corresponding output of one of the logical elements DD1.2, DD2.1, DD2.3-DD0. For example, when the binary code of the number 2,4 appears at the output counters of the tachometer, both inputs of the logical element DD2.2 of the signaling device will receive logical 1 signals and a signal 0 will appear at its output, which through the contacts of the SB3.1 button (if, of course, this button is pressed) will go to the input of the alarm trigger. The trigger, assembled on the elements DD3.1, DD3.2, will be set to a single state. From the output of the DD3.2 element, signal 1 will go to the input of the DD3.3 element and enable the operation of the signaling device assembled on the DD2.4 elements. DD3.3, DD3.4 and transistor VT1.

The upper input (pin 12) of the DD2.4 element from the tachometer multivibrator receives pulses that form an intermittent sound and a flashing light indication. The sound signal generated by the generator DD2.4. DD3.3, DD3.4, amplifies the transistor VT1, the load of which is the dynamic head BA1. For light indication of speeding, a line of LEDs VD1-VD1, switched by contacts SB5-SB1.2, is included in the collector circuit of transistor VT5.2. Depending on which button is pressed, one or another LED will turn on periodically.

The alarm trigger is periodically switched to the initial state by a signal generated by the second multivibrator of the tachometer, and again returns to the single state if the vehicle speed remains above the allowable one or remains in the zero state if the speed is reduced.

The signaling device uses a P2K switch with dependent fixation. The SA1 limit switch, similar to that used in a car to turn on the interior lighting when the door is opened, is placed under a protective cover at the base of the gear lever. This switch is installed so that its contacts open when the direct gear is engaged, and remain closed in all other positions of the lever.

All elements, except for LEDs and a dynamic head, are placed on a double-sided printed circuit board with dimensions of 80x45 mm made of foil fiberglass 1,5 mm thick (see Fig. 2). Switch buttons SB1-SB5 are displayed on the front panel. LEDs VD1-VD5 are installed above the buttons. The BA1 head must be installed so that its sound is clearly audible against the background of extraneous noise.

Overspeed signaling device

With proper installation and serviceable parts, the adjustment of the signaling device comes down to setting the desired tone of the sound signal by selecting the resistor R2 and the required sound volume by selecting the resistor R5.

The device is designed for the car "Moskvich-2140". When installing the signaling device on other vehicles, it is necessary to change the decoder circuit for other limit values of the engine crankshaft speed. The dependence of the rotational speed N (min-') of the engine crankshaft on the speed V (km / h) of the vehicle is expressed by the formula:

N=16.7VK/2pR

where K is the gear ratio of the rear axle gearbox, R is the static rolling radius of the wheel, in meters. The gear ratio of the gearbox in direct gear is 1 and therefore is not included in the formula.

It is convenient to install the device in the Moskvich-2140 car behind the instrument panel above the radio receiver.

Author: V. Perolainen Balashov, Saratov region; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Automobile. Speedometers and tachometers.

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

microphone in ear 28.04.2003

South Korean firm Samsung has developed an in-ear microphone.

The company claims it is the first in-ear microphone phone. It receives sound directly from the user's head, while filtering out about 90% of external noise. The in-ear microphone will go on sale later this year in wired and wireless (Bluetooth) versions.

The latter should especially appeal to drivers using mobile phones: while driving, they will be able to talk without even putting on a headset. Today, such a headset usually consists of headphones and a microphone at the mouth and is connected by a wire to a cell phone.

Other interesting news:

▪ Recognition of people at a distance by heartbeat

▪ Sweet makes ants more fun

▪ 6Gbps Wireless Platform

▪ Oat gold

▪ The lawn mower runs on grass and is guided by Google maps

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Home workshop. Article selection

▪ article Study of control systems. Lecture notes

▪ article How did the circus originate? Detailed answer

▪ article Barley mouse. Legends, cultivation, methods of application

▪ article Combination lock on the microcontroller. Encyclopedia of radio electronics and electrical engineering

▪ article 18 W low-voltage soldering iron power supply. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

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