The main topics presented
1. Techniques and methods for measuring earthing installations
There are several reasons for grounding, but the most important of these is to ensure the safety of personnel.
The following agencies and organizations have recommendations and / or standards for grounding, to demonstrate that personnel safety is achieved.
The organizations that offer rules and guidelines for earthing are: International Electrotechnical Commission (IEC), European Committee for Electrotechnical Standardization (CENELEC), Romanian Standardization Association (ASRO), National Association for Fire Protection, American National Standards Institute (INAS ), The Mining Health and Safety Administration (ASSM), the Occupational Health and Safety Administration (OSHA), the Standard Telecommunications Industry (TIA) and others.
Optimal grounding is not only necessary for employee safety, but also to provide overvoltage protection for buildings and equipment.
A well-designed earthing system will improve the safety of the equipment and reduce the possibility of electric shocks, damage and damage due to lightning strikes or defects in electronic circuits.
2. Temperature transducers (I) - Resistive transducers (thermistors)
In the first part it is presented sensors that convert temperature variations into resistance variations.
The existing range is varied and includes detectors from the most accurate, which are probably the ones based on platinum resistive elements - but also the most expensive, up to thermistors or heat-resistant elements made of silicon structures.
The applications are multiple and will be described separately. In figure 1 (from the article) you can see, in a graphic form, a brief comparison between the different types of resistive transducers, the range of measured temperatures, their sensitivity and linearity.
In table 1 (from the article) the costs involved in using a type of transducer are analyzed, including here - although not based on resistive detectors; for comparison only, modern transducers made in the form of an integrated circuit, with multiple functions and which include the sensor, the adapter, the A / D converter and (possibly) serial communication.
Some models can also be used as thermostats or temperature-limit detectors, either by using an internal limit prescription - possibly programmable, or by setting it with an external resistive divider.
For usual measurements in the field of ambient temperatures, their accuracy can be greatly improved, and the costs are acceptable, especially for multipoint measurements where one can benefit from the serial transmission of data, in numerical format.
3. TDA5051 - Modem through the 220Vac socket network
For a start, a brief presentation of the utility and efficiency of a modem with communication through the socket network is made and the specialized circuit TDA5051A produced by Philips Semiconductors is presented under the name Home Automation Modem (modem for home automation).
Next, the operation of a general application is proposed and explained, which allows the bidirectional connection of two or more stations, with a transmission rate between 600 and 1200 bits / s.
In the final part you can find some suggestions on the practical realization of an application.
4. Universal mobile phone interface - PC with MAX3232
The assembly presented represents a upgrade to "Universal data interface, RS232-mobile phone" presented in issue 9/2003 of Conex Club.
MAX232 is replaced with its version for low level TTL signals, respectively MAX3232. In addition, a new smaller wiring, hybrid realization technique (THT and SMT) and more signals in TTL format available.
Because the scheme is approximately similar to the one presented in the issue 9/2003 of the Conex Club on page 31, in this article we will mainly highlight the differences between the use of MAX232 and MAX3232, how to use the wiring, with small modifications, for any of these integrated circuits and other construction differences (because SMD components are also used).
5. Counter / Dispenser for packing pills
It presents a application (timer - counter) with uC AVR destined for the pharmaceutical industry: dispenser for packaging medicines.
As a continuation of the article for the presentation and description of AVR series microcontrollers, a concrete application is presented, namely a dispenser - counter used in the pharmaceutical industry for dosing the number of pills (tablets) in a tube (vial) of drugs and counting tubes loaded certain period of time (for example during a day, weeks, months, etc.).
The scheme presented in the article contains two basic components: the AT90S2313-10PI microcontroller and the M1641 type LCD display.
6. Voice encryption mode
It presents a miniature electronic assembly, made in SMT technique, for secrecy and maintaining the confidentiality of conversations.
The device is made on a double plated printed circuit board, with dimensions 2,5 x 3cm, made in SMT technology on FR4 material.
The operation is managed by a usual microcontroller, PIC16F628 </strong> Microcontroller., and the assembly is supplied with a minimum voltage of 3.7Vcc.
mounting allows its intercalation in a simplex, semi-duplex or full duplex communication network being suitable for any voice transmission medium.
Mainly, it is intended for use as such in transmission-reception stations, allowing the adaptation with minimum auxiliary components to the fixed or mobile telephony network.
In particular, for use on the fixed telephony network, the module is inserted in the electronic bridge (active or passive) inside the phone, seeking to obtain a maximum rejection of the local echo effect.
7. Intercom source - With timer and telephone call
It presents a complex voltage source which is recommended to be used in an intercom or access control system.
Offers two voltage outputs (12Vdc and 30Vdc / 1A), one control output for electromagnetic yalla (on relay, 12V / 1.5Amax) and two inputs (lock actuation control and electronic call control via buttons).
8. Anemometer - Measuring wind speed
An indispensable element in a weather station, the anemometer is the equipment for measuring wind speed.
The wiring diagram is simple, in the form of a PC interface, the communication being made on the serial port. In addition, the power is supplied from the same port.
The mechanical part is harder to achieve, but going through the lines of the article, everything will seem simple! Basically, the hemispheres in the figure are halves of ping-pong balls, and the base is made of two plastic tubes, as recommended by the source (PC Interfaces, author David Rey) plastic tubes recovered from drugs!
The transducer is an optocoupler with slot, known to readers of the "Contest" section of December 2003.
The fixed part of the mechanical construction is a simple tube used for packaging medicines, its length is not important, but the diameter must be minimal 30 mm.
A ball bearing will be mounted at its base. The moving part is made of a tube of the same size, but with a much shorter length, recommended 20 mm.
On this second tube will be mounted 3 hemispheres obtained from ping-pong balls (supported by screws), arranged at 120 degrees.