Electronic Relay Research Articles

The synchronized astable multivibrator bridge as an error detector of an on-off servomechanism

The synchronized astable multivibrator bridge using time delay between pulses, is a new temperature- stabilized linear transducer and a measuring device with a digital counter of R or C parameter changes or corresponding nonelectric quantities. It is used as an error detector, compatible with an electronic relay, bistable multivibrator or corresponding flip-flop integrated circuit, in a simple and reliable on-off servomechanism whose hysteresis or dead zone corresponds to relative changes of a variable element of about 10-5. This servomechanism is convenient for measurement, control, command or recording, especially for remote operations. Applied with thyristors it can be used as a sensitive and contactless thermostat or switcher.

An Inexpensive Electronic Relay for Precise Water-Temperature Control

An Inexpensive Electronic Relay for Precise Water-Temperature Control

Turing Machines and the Mind-Body Problem

i In his [1961] Hilary Putnam has argued that 'all the issues and puzzles that make up the traditional mind-body problem ... arise in connection with any computing system capable of answering questions about its own structure'. This shows, he believes, that such issues and puzzles are wholly linguistic or logical in character, and 'have thus nothing to do with the unique nature (if it is unique) of human subjective experience'.1 His argument makes use of the notion of a Turing machine. Such a machine consists of (a) a physical tape, scanner and printing device, along with a control and storage mechanism, and (b) a machine table which comprises a set of instructions for the machine to follow, and which directs the machine to print, erase or move the tape as required. There are thus two kinds of descriptions which can be given of a Turing Machine, the one called its logical description which concerns only the table of rules and instructions and does not presuppose any specific physical embodiment (it may be electronic relays, clerks sitting at desks, or whatever), and the other called its structural or physical description which applies to the specific system chosen to carry out the instructions of the machine table. These two types of descriptions, Putnam goes on to note, are closely analogous to the two types of descriptions typically applied to human beings, namely the psychological and the physical. Thus, the physical description of a human being corresponds to the physical (or structural) description of the machine, and the psychological description corresponds to the logical. A few words of explanation are needed for the second half of this analogy. Putnam makes the following three points in this connection:

The operant manipulation of vocal pitch in normal speakers.

A device consisting of variable electronic filters and voice-actuated relays was used to raise or lower the vocal pitch of four normal-speaking subjects by the differential reinforcement of selected frequencies emitted by them during oral reading. Continuous, fixed interval, fixed ratio, and variable interval reinforcement schedules were applied to each subject. The results of the study indicated that fundamental vocal frequency is a manipulable operant response. All reinforcement schedules examined produced high rates of response at the selected frequency for all subjects. The variable interval schedules produced the most consistent, high durations of response for all subjects. The method of manipulation of fundamental frequency investigated in the study appears to have promise as a therapeutic technique, especially for deaf speakers and clients with functional pitch disorders.

Theory and design of electronic relays

A unified theory on the principles and characterizations of electronic relays is presented. A basic realization scheme is shown to consist of a cascade connection of an isolation box, an analog-to-binary converter, and an electronic switch. A total of eight canonic realizations are given for synthesizing each of the four types of electronic relays. In conclusion the design of two complete practical electronic relays is presented and the actual performance is verified through experimental measurements.

Characteristics of Excursions above a High Level for a Gaussian Process and Its Envelope

Characteristics of Excursions above a High Level for a Gaussian Process and Its Envelope

Measurement of Contact Resistance

An instrument for measuring the long term quality of electrical connecting devices is described. The parameter which controls this property is the contact resistance. In the instrument described, the contact and bulk resistance are separated by utilizing the difference in thermal response time between a contact spot and bulk metal. The circuits, mode of operation, and applications of the instrument are discussed. Contact resistance can be measured within 5% in most electronic connectors, switches, and relays.

Inhibition by temperature of the terminal step in biosynthesis of prodigiosin

This chapter presents a discussion on the effects and control of temperature on micro-organisms and microbiological studies. The pioneer microbiologists realized that the rate of growth of a microbe is affected by the environmental temperature, and several studies on the effect of temperature on growth of pure cultures of microorganisms have been made. In a given medium, a microbe grows most rapidly at a particular temperature (or over a small range of temperatures) that is referred to as the ‘optimum temperature’ for growth. In most studies, the optimum temperature for growth is based upon the rate of growth, although it is occasionally based instead on the size of the crop of micro-organisms produced. It is common practice to store stock cultures of micro-organisms on, or in, solidified nutrient media at a temperature near or below the minimum for growth of the organisms on that medium. Anhydric incubators satisfy the requirements of most microbiological laboratories when the need is often only to incubate static cultures under conditions where variations in temperature are not critical. Temperature-gradient incubators have been used to study the effect of temperature on growth of bacteria, yeasts, and algae. A contact thermometer and electronic relay are now almost universally used for control of bath temperature in apparatus used for manometric work.

Transistorized 2-24 channel carrier telegraph equipment

The transistorized 2×24-channel carrier telegraph equipment consists of two FM (frequency modulation) type 24-channel systems in a bay, as recommended by the CCITT (International Telegraph and Telephone Consultative Committee). Taking account of the major weakness of the transistor circuit and of the center frequency variation of the FM system caused by temperature rise, the various parts and circuits have been specially designed, including, for example, the use of afc (automatic frequency control), electronic relay, and special circuits for the oscillator and discriminator. This paper describes these features and characteristics.

A New Current-Sensing Device

Development of a reliable, low-cost current sensing device was undertaken for use in capacitor switching, load study, and protective relaying. The unit takes the form of an inductive pick-up coil imbedded in a porcelain insulator. It may be used on straight conductor runs with an accuracy of ±6% before applying correction factors which depend on physical configuration and size of conductor. Output impedance is high, suggesting use of high-impedance loads. Sufficient power is available to operate electronic equipment and sensitive relays.

Electronic relay for a printing chronograph

Electronic relay for a printing chronograph

Inexpensive electronic relay for use with toluene regulators

Inexpensive electronic relay for use with toluene regulators

Thermostat suitable for controlling air temperature, particularly in biological research

Some of the features essential to the control of air temperature in small and unlagged containers are outlined, and apparatus is described which will control the temperature in such a container to ±1/50° C. A system of continuous proportional control is used, based on a two-stage directly coupled amplifier whose input is dependent on the resistance of a thermistor, and whose output is fed directly to the heating element. Incorporation of variable positive feedback makes it possible to attain high sensitivity, or alternatively to use the equipment without modification as a switching thermostat and electronic relay for large power loads. A description is also included of a temperature-measuring system based on a thermistor, which will display the air temperature to ±1/50° C.

Electronic time relays

Electronic time relays

Small dual electronic relays with grid contact

Small dual electronic relays with grid contact

A Design Technique for Pedestal-Free Switching Circuits

The fundamental differences between mechanical and electronic switching circuits are discussed with special emphasis on the problem of pedestals. Based on the fundamental differences it is shown that Boolean algebra fails to express practical requirements of electronic switches. This paper takes a step in the direction of removing this limitation by augmenting the ON-OFF notation of Boolean algebra by a notation of inequalities to handle the problem of pedestal-free switching. The ideal electronic relay is defined and a diode network realization is synthesized. An electronic switch is synthesized to illustrate the design technique's application. Photographs showing the performance of the circuits are given.

Discussion on “An electronic over-current relay for electrical machines”

Discussion on “An electronic over-current relay for electrical machines”

An electronic relay

An electronic relay

An electronic over-current relay for electrical machines

The paper describes an electronic relay designed to protect electrical machines under over. current conditions. The advantages of this device over conventional thermal and magnetic protective relays are outlined, and methods of connection for single- and multi-phase working are discussed.

Power system protection, with particular reference to the application of junction transistors to distance relays

The object of the paper is to describe early experience in designing and testing high-speed distance relays using junction transistors, and to expose the main difficulties in this field. The paper reviews briefly the history and application of electronic relays to electrical power-system protection and considers the general advantages of junction transistors over thermionic valves for this purpose. The principles of two distance relays using junction transistors are described, and it is shown that there is no theoretical difficulty in obtaining a range of relay characteristics within the general classification of ?distance relay?, together with the properties of a straightforward directional relay. The particular susceptibility of the ?mho?-type distance relay and of the directional relay to collapse of line voltage is then discussed. The circuits of the pulse type and direct phase comparison types of relay are described, together with the relay test arrangement and a brief exposition of the method of presenting the relay characteristics. The operating characteristics of the relays, as expressed by accuracy/range curves, are explained, it being shown that the direct phase comparison type is more successful than the pulse type but that both are extremely susceptible to transient overreach; the nature of this latter phenomenon is discussed. It is concluded that junction transistors have some important operational advantages over thermionic valves where electronic protection can be justified, but that, in particular, the application of junction transistors, in common with conventional electronic circuits, to high-speed distance relays is dependent upon a satisfactory solution of the transient overreach problem; two possible ways of overcoming this latter difficulty are advocated. The rapid development of transistors is bringing their rating, power and length of life into a situation where it is thought they will be of importance in the design of new protective-gear relays and systems.