1. How can you tell when overflow occurs?
2. How can you tell when underflow occurs?
3. What is the function of clear input?
4. What is the function of data output?
33 2
Fill in the blanks with suitable words.
1. Data input and load input for ... counter to desirable initial number.
2. Carry output is for indication ... of counter. 3. The reversible counters have the following inputs: clock pulses inputs for ... and counting up.
34 3
Speak on the cascading of counters using the words below:
1-. counter, design, cascade; 2. both, borrow, carry, output, available, up, down, counting, function; 3. borrow, produce, pulse, counter, underflow;
4. similarly, carry, produce, pulse, overflow, occur.
35 3
Complete the following sentences in such a way that they make sense. Compare your results with the text.
1. The counters can be easily cascaded by... . 2. The output will change to agree with.... 3. Counters are fully programmable that is. .. .
36 6
Work in pairs. Explain the theory of relativity to your fellow student.
37 15 Check your reading skills. See ex. 32, Section 1, Unit 2.
Automation
Automation has been, and is still, a greatly misused word but its proper meaning and, therefore, its implications, is gradually becoming better understood. It is a concept through which a machine system is caused to operate) with maximum efficiency by means of adequate measurement, observation and control. It involves a detailed and continuous knowledge of the functioning of the system so that the best corrective actions can be applied as soon as they become necessary. Thus automation should produce the optimum result. Unfortunately the word has gathered many wrong and half-wrong associations all of which imply mechanization, which in turn implies unthinking repetitive motion and this is the exact opposite of automation.
Fill in the blanks:
1. Automation has been, and is still, a greatly ... . a) misused word;
b) elimination of practical human judgement; c) essential skill and experience of an operator.
2. Automation is a concept through which ... is caused to operate with maximum efficiency by means of adequate measurement, observation and control, a) mechanization; b) unthinking repetitive motion; c) a machine system.
3. Automation involves a detailed and continuous knowledge of the functioning of the system so that ... as soon as they become necessary.
a) the skill and experience of the trained operator will still be essential;.
b) the best corrective actions can be applied; c) the engineer’s aim has always been to make the best use of machines, materials and money.
Now record your time and results.
Give the exact translation.
Frequency
The number of cycles per second is the frequency of an a-c. There are two frequencies: the standard for Europe is 50 cycles per second while the standard for the USA is 60 cycles per second. A standard frequency has a great advantage since different systems can be interconnected.
39 3
Ask each other questions covering the text.
Electronic Control of Motors
It is necessary to control motors. That is, motors must be started, stopped, and reversed, and, within limits, it must bej possible to control their speed.
The controls needed to perform these various functions on d-c motors are designed to alter the quantity or the direction of the current in the field or in the armature of the motor. On d-c controls, these functions were shown to consist mainly of resistances, switches, and solenoids.
It is possible to control motors, not only electromechanically an-d electromagnetically, but also electronically, by means of vacuum tubes or gas-filled tubes. Some electronic devices can be made to operate a relay which in turn controls a motor. Others influence the amount and direction of current flowing in the motor circuit and thus the action of the motor itself. Both types may be found in one control device.
40 3
Work in pairs. Dwell with your fellow-student on basic elements of automation. Use ex. 19, 20, 37, 39.
