P4 Electronics. Digital technology. and basic circuits. Operational amplifier. P 4.3 Open- and closed-loop control

Transcription

1 Electronics

2 Table of contents Electronics P4 Electronics P 4.1 Components and basic circuits P Current and voltage sources P Special resistors 153 P Diodes 154 P Diode circuits 155 P Transistors 156 P 4.1.6Transistor circuits 157 P Optoelectronics 158 P 4.4 Digital technology P Basic logical operations 163 P Switching networks and units 164 P Serial and parallel arithmetic units 165 P Digital control systems 166 P Structure of a central processing unit (CPU) 167 P 4.4.6Microprocessor 168 P 4.2 Operational amplifier P Internal design of an operational amplifier 159 P Operational amplifier circuits 160 P 4.3 Open- and closed-loop control P Open-loop control 161 P Closed-loop control

3 Electronics Components and basic circuits P4.1.1 Current and voltage sources P P Determining the internal resistance of a battery Operating a DC power supply as a constant-current and constant-voltage source Determining the internal resistance of a battery (P ) Battery case 2 x 4.5 Volt Set of 20 batteries 1.5 V (type MONO) AC/DC power supply V 1 Voltmeter, DC, U 10 V, e. g Multimeter LDanalog 20 1 Ammeter, DC, I 3 A, e. g Multimeter LDanalog 20 1 Ammeter, DC, I 6 A, e. g Multimeter LDanalog 30 1* Rheostat 10 V Connecting lead, Ø 2.5 mm 2, 25 cm, black Connecting lead, Ø 2,5 mm 2, 50 cm, red 1* Connecting lead, Ø 2,5 mm 2, 50 cm, blue 1* Connecting lead, Ø 2.5 mm 2, 100 cm, red Connecting lead, Ø 2.5 mm 2, 100 cm, blue 1 * additionally recommended P P The voltage U 0 generated in a voltage source generally differs from the terminal voltage U measured at the connections as soon as a current I is drawn from the voltage source. A resistance R i must therefore exist within the voltage source, across which a part of the generated voltage drops. This resistance is called the internal resistance of the voltage source. In the first experiment, a rheostat as an ohmic load is connected to a battery to determine the internal resistance. The terminal voltage U of the battery is measured for different loads, and the voltage values are plotted over the current I through the rheostat. The internal resistance R i is determined using the formula U=U 0 R i I by drawing a best-fit straight line through the measured values. A second diagram illustrates the power P=U I as a function of the load resistance. The power is greatest when the load resistance has the value of the internal resistance R i. The second experiment demonstrates the difference between a constant-voltage source and a constant-current source using a DC power supply in which both modes are implemented. The voltage and current of the power supply are limited to the respective values U 0 and I 0. The terminal voltage U and the current I consumed are measured for various load resistances R. When the load resistance R is reduced, the terminal voltage retains a constant value U 0 as long as the current I remains below the set limit value I 0. The DC power supply operates as a constant-voltage source with an internal resistance of zero. When the load resistance R is increased, the current consumed remains constant at I 0 as long as the terminal voltage does not exceed the limit value U 0. The DC power supply operates as a constant-current source with infinite internal resistance. 151

4 Components and basic circuits Electronics P4.1.1 Current and voltage sources P Recording the current-voltage characteristics of a solar battery as a function of the irradiance Recording the curent-voltage characteristics of a solar battery as a function of the irradiance (P ) The solar cell is a semiconductor photoelement in which irradiance is converted directly to electrical energy at the p-n junction. Often, multiple solar cells are combined to create a solar battery. In this experiment the current-voltage characteristics of a solar battery are recorded for different irradiance levels. The irradiance is varied by changing the distance of the light source. The characteristic curves reveal the characteristic behavior. At a low load resistance, the solar battery supplies an approximately constant current. When it exceeds a critical voltage (which depends on the irradiance), the solar battery functions increasingly as a constant-voltage source STE solar battery 2 V / 0.3 A Plug-in board, DIN A Pair of holders for rastered socket panel STE potentiometer 220 V, 3 W Set of 10 bridging plugs 1 Voltmeter, DC, U 3 V, e. g Multimeter LDanalog 20 1 Ammeter, DC, I 200 ma, e. g Multimeter LDanalog Halogen lamp housing 12 V, 50/100W Halogen lamp, 12 V/100 W Transformer V Saddle base Pair of cables, 50 cm, red and blue Pair of cables, 100 cm, black 1 P Current-voltage characteristics for different illuminance levels 152

5 Electronics Components and basic circuits P4.1.2 Special resistors P P P P Recording the current-voltage characteristic of an incandescent lamp Recording the current-voltage characteristic of a varistor Measuring the temperaturedependency of PTC and NTC resistors Measuring the light-dependency of photoresistors Recording the current-voltage characteristic of an incandescent lamp (P ) Set of 10 lamps E 10; 12 V/3 W Lamp with socket E 10; 6.0 V/5.0 W Plug-in board section STE VDR-resistor STE photoresistor LDR STE NTC probe 4.7 ke STE PTC probe 30 E STE lamp holder, E10, lateral STE lamp holder E10, top DC power supply V, 5A Transformer, 6 V AC,12 V AC/30 VA 1 Voltmeter, DC, U 20 V, e.g Multimeter LDanalog Ammeter, DC, I 3 A, e.g Multimeter LDanalog USB Power-CASSY CASSYLab Steel tape measure, 2 m Thermometer, -10 to C Hot plate, 150 mm dia., 1500 W Beaker, 400 ml, ss, hard glass Connecting lead, red 100 cm Pair of cables, 50 cm, red and blue Pair of cables, 100 cm, black 1 additionally required: 1 PC with Windows 95/NT or higher 1 P P P P Many materials do not conduct voltage and current in proportion to one another. Their resistance depends on the current level. In technical applications, elements in which the resistance depends significantly on the temperature, the luminous intensity or another physical quantity are increasingly important. In the first experiment, the computer-assisted measured-value recording system CASSY is used to record the current-voltage characteristic of an incandescent lamp. As the incandescent filament heats up when current is applied, and its resistance depends on the temperature, different characteristic curves are generated when the current is switched on and off. The characteristic also depends on the rate of increase du/dt of the voltage. The second experiment records the current-voltage characteristic of a varistor (voltage dependent resistor). Its characteristic is non-linear in its operating range. At higher currents, it enters the so-called rise range", in which the ohmic component of the total resistance increases. The aim of the third experiment is to measure the temperature characteristics of an NTC thermistor resistor and a PTC thermistor resistor. The respective measured values can be described using empirical equations in which only the rated value R 0, the reference temperature T 0 and a material constant appear as parameters. The subject of the final experiment is the characteristic of a CdS light-dependent resistor. Its resistance varies from approx. 100 V to approx. 10 MV, depending on the brightness. The resistance is measured as a function of the distance from an incandescent lamp which illuminates the light-dependent resistor. 153

6 Components and basic circuits Electronics P4.1.3 Diodes P P P Recording the current-voltage characteristics of diodes Recording the current-voltage characteristics of zener diodes Recording the current-voltage characteristics of light-emitting diodes (LEDs) Recording the current-voltage characteristics of light-emitting diodes (LEDs) (P ) Virtually all aspects of electronic circuit technology rely on semiconductor components. The semiconductor diodes are among the simplest of these. They consist of a semiconductor crystal in which an n-conducting zone is adjacent to a p-conducting zone. Capture of the charge carriers, i.e. the electrons in the n-conducting and the holes in the p-conducting zones, forms a lowconductivity zone at the junction called the depletion layer. The size of this zone is increased when electrons or holes are removed from the depletion layer by an external electric field with a certain orientation. The direction of this electric field is called the reverse direction. Reversing the electric field drives the respective charge carriers into the depletion layer, allowing current to flow more easily through the diode. In the first experiment, the current-voltage characteristics of an Si-diode (silicon diode) and a Ge-diode (germanium diode) diode are measured and graphed manually point by point. The aim is to compare the current in the reverse direction and the threshold voltage as the most important specifications of the two diodes. The objective of the second experiment is to measure the current-voltage characteristic of a zener or Z-diode. Here, special attention is paid to the breakdown voltage in the reverse direction, as when this voltage level is reached the current rises abruptly. The current is due to charge carriers in the depletion layer, which, when accelerated by the applied voltage, ionize additional atoms of the semiconductor through collision Rastered socket panel, DIN A STE Resistor 100 E, 2 W STE light emitting diode LD 57 C, green STE light emitting diode yellow, LED 3, top STE light emitting diode red, LED 2, top STE light emitting diode LD 271 H, infrared STE Ge-diode AA STE Si-diode 1 N STE Z-diode ZPD STE Z-diode ZPD AC/DC-Power supply, V, 230 V/50 Hz Voltmeter, DC, U 10 V, e.g. Multimeter LDanalog Ammeter, DC, I 150 ma, e.g Multimeter LDanalog Connecting lead, red 100 cm Pair of cables, 50 cm, red and blue P P P The final experiment compares the characteristics of infrared, red, yellow and green light-emitting diodes. The threshold voltage U is inserted in the formula e U = h c Ö e: electron charge, c: velocity of light, h: Planck s constant, to estimate the wavelength Ö of the emitted light. 154

7 Electronics Components and basic circuits P4.1.4 Diode circuits P P P Rectification of AC voltages with diodes Limiting voltages with a Z-diode Testing polarity with light emitting diodes. Rectification of AC voltages with diodes (P ) Plug-in board, DIN A STE resistor 680 E, 2 W STE light emitting diode red, LED 2, top STE light emitting diode LD 57 C, green STE Si-diode 1 N STE Z-diode ZPD STE lamp holder, E10, top Set of 10 bridging plubs Set of 10 lamps E 10; 12 V/3.0 W AC/DC power supply V, 230 V/50 Hz Two channel oscilloscope Screened cable BNC/4 mm 1 Voltmeter, AC/DC, U 12 V, e. g Multimeter LDanalog 20 1 Voltmeter, DC, U 12 V, e. g Multimeter LDanalog Pair of cables, 50 cm, red and blue P P P Diodes, zener diodes (or Z-diodes) and light-emitting diodes are used today in virtually every electronic circuit. The first experiment explores the function of half-wave and fullwave rectifiers in the rectification of AC voltages. The half-wave rectifier assembled using a single diode blocks the first half-wave of every AC cycle and conducts only the second half-wave (assuming the diode is connected with the corresponding polarity). The full-wave rectifier, assembled using four diodes in a bridge configuration, uses both half-waves of the AC voltage. The second experiment demonstrates how a Z-diode can be used to protect against voltage surges. As long as the applied voltage is below the breakdown voltage U Z of the Z-diode, the Z- diode acts as an insulator and the voltage U is unchanged. At voltages above U Z, the current flowing through the Z-diode is so high that U is limited to U Z. The aim of the last experiment is to assemble a circuit for testing the polarity of a voltage using a green and a red light emitting diode (LED). The circuit is tested with both DC and AC voltage. 155

8 Components and basic circuits Electronics P4.1.5 Transistors P P P Investigating the diode characteristics of transistor junctions Recording the characteristics of a transistor Recording the characteristics of a field-effect transistor Recording the characteristics of a transistor (P ) Transistors are among the most important semiconductor components in electronic circuit technology. We distinguish between bipolar transistors, in which the electrons and holes are both involved in conducting current, and field-effect transistors, in which the current is carried solely by electrons. The electrodes of a bipolar transistor are called the emitter, the base and the collector. The transistor consists of a total of three n-conducting and p-conducting layers, in the order npn or pnp. The base layer, located in the middle, is so thin that charge carriers originating at one junction can cross to the other junction. In field-effect transistors, the conductivity of the current-carrying channel is changed using an electrical field, without applying power. The element which generates this field is called the gate. The input electrode of a field-effect transistor is known as the source, and the output electrode is called the drain. The first experiment examines the principle of the bipolar transistor and compares it with a diode. Here, the difference between an npn and a pnp transistor is explicitly investigated. The second experiment examines the properties of an npn transistor on the basis of its characteristics. This experiment measures the input characteristic, i.e. the base current I B as a function of the base-emitter voltage U BE, the output characteristic, i.e. the collector current I C as a function of the collector-emitter voltage U CE at a constant base current I B and the collector current I C as a function of the base current I B at a constant collectoremitter voltage U CE. In the final experiment, the characteristic of a field-effect transistor, i. e. the drain current I D, is recorded and diagrammed as a function of the voltage U DS between the drain and source at a constant gate voltage U G Plug-in board, DIN A STE resistor 100 Ω, 2 W STE resistor 1 kω, 2 W STE resistor 47 kω, 0,5 W STE potentiometer 220 Ω, 3 W STE potentiometer 1 kω, 1 W STE transistor BD 137, NPN, emitter bottom STE transistor BD 138, PNP, emitter bottom STE transistor BF 244 (FET) STE Si-diode 1 N Set of 10 bridging plugs AC/DC power supply V, 230 V/50 Hz DC power supply 0... ± 15 V Transformer, 6 V ~, 12 V ~/30 W 1 Ammeter, DC, I 100 ma, e.g Multimeter LDanalog Voltmeter, DC, U 12 V, e. g Multimeter LDanalog Two-channel oscilloscope Screened cable BNC/4 mm Connecting lead, blue, 50 cm Pair of cables, 50 cm, red and blue P P P

9 Electronics Components and basic circuits P4.1.6 Transistor circuits P P P P P P Transistor as amplifier Transistor as switch Transistor as sine-wave generator (oscillator) Transistor as function generator Field-effect transistor as amplifier Field-effect transistor as switch Transistor as amplifier (P ) P (a) P (b) P P P P P Rastered socket panel DIN A STE transistor BD 137, NPN, emitter bottom STE transistor BC 140, NPN, emitter bottom STE transistor BC 140, NPN, emitter top STE FET transistor BF STE resistor 1 ke, 2 W STE resistor 1.5 ke, 2 W STE resistor 10 ke, 0.5 W STE resistor 15 ke, 0.5 W STE resistor 33 ke, 0.5 W STE resistor 47 ke, 0.5 W STE resistor 68 ke, 0.5 W STE resistor 100 ke, 0.5 W STE resistor 1 ME, 0.5 W STE regulation resistor 10 ke, 1 W STE regulation resistor 4.7 ke, 1 W STE regulation resistor 47 ke, 1 W STE regulation resistor 1 ke, 1 W STE photoresistor LDR STE PTC probe 30 W STE capacitor 0.22 µf, 250 V STE capacitor 4.7 µf, 63 V STE capacitor 100 pf, 630 V STE capacitor 220 pf, 160 V STE capacitor 0.47µF, 100 V STE capacitor 1 µf, 100 V STE capacitor 2.2 µf, 63 V STE electrolytic capacitor 47 µf, 40 V Transistor circuits are investigated on the basis of a number of examples. These include the basic connections of a transistor as an amplifier, the transistor as a light-dependent or temperaturedependent electronic switch, the Wien bridge oscillator as an example of a sine-wave generator, the astable multivibrator, basic circuits with field-effect transistors as amplifiers as well as the field-effect transistor as a low-frequency switch STE electrolytic capacitor 100 µf, 35 V STE electrolytic capacitor 470 µf, 16 V STE electrolytic capacitor 220 µf, 35 V STE Si-diode 1 N STE Lamp holder E10, top STE toggle switch, single-pole STE heating element, 100 W, 2 W Set of 10 bridging plugs Set of 10 lamps E 10; 12 V/3 W Glow lamp E 10; 15 V/2.0 W Function generator S 12, 0.1 Hz to 20 khz AC/DC power supply V, 230 V/50 Hz DC power supply 0...+/- 15 V Two-channel oscilloscope Screened cable BNC/4 mm Multimeter LDanalog Connecting lead, Ø 2.5 mm 2, 50 cm, black Pair of cables, 50 cm, red and blue Pair of cables, 50 cm, black 1 1 P (a) P (b) P P P P P

10 Components and basic circuits Electronics P4.1.7 Optoelectronics P P Recording the characteristics of a phototransistor connected as a photodiode Assembling a purely optical transmission line Assembling a purely optical transmission line (P ) Optoelectronics deals with the application of the interactions between light and electrical charge carriers in optical and electronic devices. Optoelectronic arrangements consist of a lightemitting, a light-transmitting and a light-sensitive element. The light beam is controlled electrically. The subject of the first experiment is a phototransistor without base terminal connection used as a photodiode. The currentvoltage characteristics are displayed on an oscilloscope for the unilluminated, weakly illuminated and fully illuminated states. It is revealed that the characteristic of the fully illuminated photodiode is comparable with that of a Z-diode, while no conducting-state behavior can be observed in the unilluminated state. The second experiment demonstrates optical transmission of the electrical signals of a function generator to a loudspeaker. The signals modulate the light intensity of an LED by varying the onstate current; the light is transmitted to the base of a phototransistor via a flexible light waveguide. The phototransistor is connected in series to the speaker, so that the signals are transmitted to the loudspeaker Rastered socket panel, DIN A STE light emitting diode LD 57C, green STE light emitting diode CQV 51J, red STE photodiode BPX P (a) P (b) P STE transistor BD 138, PNP, emitter bottom STE operational amplifier LM STE resistor 47 E, 2 W STE resistor 100 E, 2 W STE resistor 470 E, 2 W STE resistor 1 ke 2 W STE resistor 2.2 ke, 2 W STE resistor 10 ke, 0.5 W STE resistor 47 ke, 0.5 W STE capacitor 4.7 µf, 63 V STE electrolytic capacitor 100 µf, 35 V STE electrolytic capacitor 470 µf, 16 V STE lamp holder E 10, lateral Set of 10 lamps E 10, 12 V/3 W AC/DC power supply V, 230 V/50 Hz DC power supply 0...+/- 15 V Transformer, 6 V AC,12 V AC/30 VA Two-channel oscilloscope Screened cable BNC/4 mm 2 2 Ammeter, DC, I 150 ma, e.g Multimeter LDanalog Earphone, 2 ke Function generator S 12, 0.1 Hz to 20 khz Set of 10 bridging plugs Pair of cables, 50 cm, red and blue Connection lead, 50 cm, black Connection lead, 25 cm, black 3 P (a) P (b) P

11 Electronics Operational amplifier P4.2.1 Internal design of an operational amplifier P Discrete assembly of an operational amplifier as a transistor circuit Discrete assembly of an operational amplifier as a transistor circuit (P ) Rastered socket panel, DIN A STE resistor 1 ke, 0.5 W STE resistor 10 ke, 0.5 W STE resistor 100 ke, 0.5 W STE resistor 10 E, 2 W STE resistor 220 E, 2 W STE resistor 330 E, 2 W STE resistor 470 E, 2 W STE resistor 1 ke, 2 W STE resistor 4.7 ke, 2 W STE 10-turn potentiometer 1 ke, 2 W STE capacitor 0.1 µf, 100 V STE electrolytic capacitor 100 µf, 35 V STE Si-diode 1 N STE Z-diode ZPD STE transistor BC 550, NPN, emitter bottom STE transistor BC 550, NPN, emitter top STE transistor BC 560, PNP, emitter top Set of 10 bridging plugs DC power supply 0...+/- 15 V 1 P Many electronics applications place great demands on the amplifier. The ideal characteristics include an infinite input resistance, an infinitely high voltage gain and an output voltage which is independent of load and temperature. These requirements can be satisfactorily met using an operational amplifier. In this experiment, an operational amplifier is assembled from discrete elements as a transistor circuit. The key components of the circuit are a difference amplifier on the input side and an emitter-follower stage on the output side. The gain and the phase relation of the output signals are determined with respect to the input signals in inverting and non-inverting operation. This experiment additionally investigates the frequency characteristic of the circuit. Circuit diagram of an operational amplifier assembled from discrete components Function generator S 12, 0.1 Hz to 20 khz Two-channel oscilloscope Screened cable BNC/4 mm Connecting lead, black, 25 cm Connecting lead, black, 50 cm Connecting lead, black, 100 cm Pair of cables, 50 cm, red and blue 1+1* Pair of cables, 1 m, red and blue 1 Multimeter with diode tester, e.g Analog-digital multimeter C.A * * additionally recommended 159

12 Operational amplifier Electronics P Operational amplifier circuits P P P P P Unconnected operational amplifier (comparator) Inverting operational amplifier Non-inverting operational amplifier Adder and subtracter Differentiator and integrator Adder and subtracter (P ) The first experiment shows that the unconnected operational amplifier overdrives for even the slightest voltage differential at the inputs. It generates a maximum output signal with a sign corresponding to that of the input-voltage differential. In the second and third experiments, the output of the operational amplifier is fed back to the inverting and non-inverting inputs via resistor R 2. The initial input signal applied via resistor R 1 is amplified in the inverting operational amplifier by the factor V = R 2 R 1 and in the non-inverting module by the factor V = R2 + 1 R 1 The fourth experiment demonstrates the addition of multiple input signals and the subtraction of input signals. The aim of the final experiment is to use the operational amplifier as a differentiator and an integrator. For this purpose, a capacitor is connected to the input resp. the feedback loop of the operational amplifier. The output signals of the differentiator are proportional to the change in the input signals, and those of the integrator are proportional to the integral of the input signals Function generator S 12, 0.1 Hz to 20 khz Two-channel oscilloscope Screened cable BNC/4 mm Multimeter LDanalog Connection lead, 50 cm, black P P P P P P P P P P Plug-in board, DIN A STE operational amplifier LM STE resistor 100 E, 2 W STE resistor 330 E, 2 W STE resistor 470 E, 2 W STE resistor 1 ke, 2 W STE resistor 1.5 ke, 2 W STE resistor 2.2 ke, 2 W STE resistor 3.3 ke, 2 W STE resistor 4.7 ke, 2 W STE resistor 10 ke, 0.5 W STE resistor 15 ke, 0.5 W STE resistor 22 ke, 0.5 W STE resistor 33 ke, 0.5 W STE resistor 39 ke, 0.5 W STE resistor 47 ke, 0.5 W STE resistor 100 ke, 0.5 W STE resistor 470 ke, 0.5 W STE resistor 1 ME, 0.5 W STE regulation resistor 10 ke, 1 W STE potentiometer 100 ke, 1 W STE capacitor 1 µf, 100 V STE capacitor 4.7 µf, 63 V STE capacitor 2.2 nf, 160 V STE capacitor 10 nf, 100 V STE Si diode 1 N STE transistor BC 140, NPN, emitter bottom Set of 10 bridging plugs DC power supply 0...+/- 15 V

13 Electronics Open- and closed-loop control P4.3.1 Open-loop control P P Assembling a traffic-light control system Assembling a model for control of stairway illumination Assembling a traffic-light control system (P ) P P Rastered socket panel, DIN A STE lamp socket E 10, top STE key switch n.o. single-pole STE dual program disk with cams STE motor 12 V /4 W, with gear Set of 10 bridging plugs Set of 10 lamps E 10; 12 V/3 W Set of 10 lamps E 10; 4.0 V/0.16 W AC/DC power supply V, 230 V/50 Hz Pair of cables, 100 cm, red and blue Pair of cables, 100 cm, black 1 Control is the term for any process in which the input variables of a system influence the output variables. The type of influence depends on the individual system. In the first experiment, the red, yellow and green phases of a traffic light are controlled cyclically by means of three cam disks driven by a common shaft. Here, the elastic switching tabs are actuated as the on and off switches for the individual lights. When the cam disks are provided with the appropriate pluggable cams, the three phases of the traffic light are controlled in a sensible sequence. The second experiment examines how a stairway illumination system is controlled. Pressing a pushbutton switches on the lighting and the drive motor of the cam disk at the same time. Both remain on for a period which is determined by the number of cams attached to the disk. 161

14 Open- and closed-loop control Electronics P Closed-loop control P P Assembling a model for servo control Brightness control with CASSY P Voltage control with CASSY Brightness control with CASSY (P ) Voltage control with CASSY (P ) P (a) P (b) P P P (a) P (b) P P Rastered socket panel, DIN A Rastered socket panel, DIN A STE resistor 10 kω, 0.5 W STE resistor 10 Ω, 2 W STE resistor 20 Ω, 2 W STE resistor 47 Ω, 2 W STE resistor 100 Ohm, 2 W STE resistor 2.2 kω, 2 W STE resistor 100 kω, 0.5 W STE resistor 1 MΩ, 0.5 W STE resistor 10 MΩ, 0.5 W STE regulation resistor 1 kω, 1 W STE regulation resistor 4.7 kω, 1 W STE photoresistor LDR 05 1 In the first experiment, a model of a servo control is assembled which consists of a P-controller with downstream operating amplifier as power controller, a set-point potentiometer and a motor potentiometer as servo drive. The aim of the two other experiments is the computer-aided realization of closed control loops. In the one case, a PI controller is assembled and used to control an incandescent lamp whose brightness is measured using a photoresistor. The other configuration controls a generator which supplies a constant voltage independently of the load STE capacitor 10 nf, 100 V STE capacitor 0.1 µf, 100 V STE capacitor 1 µf, 100 V STE power OP amp TCA STE lamp socket E 10, side STE lamp socket E 10, top STE toggle switch, single pole STE motor and tachogenerator STE potentiometer 4.7 kω, 2 W STE motor potentiometer 4.7 kω, 2 W Set of 10 bridging plugs Set of 10 lamps E 10; 3.8 V/0.27 W USB Power CASSY Current supply box USB Sensor CASSY CASSYLab Two-channel oscilloscope Screened cable BNC/4 mm Plastic tubing, 6 mm int. dia Pair of cables, 100 cm, red and blue Set 30 connecting leads DC power supply 0...+/- 15 V 1 1 additionally required: 1 PC with Windows 95/NT or higher DC power supply 0...+/-15 V 1 1

15 Electronics Digital technology P4.4.1 Basic logical operations P P P AND, OR, XOR, NOT, NAND and NOR operations with two variables De Morgan's laws Operations with three variables AND, OR, XOR, NOT, NAND and NOR operations with two variables (P ) SIMULOG LS-TTL, P 1 Basic logic circuits Base plate DIN A 4 for SIMULOG LS-TTL Regulated power supply, 2 x 5 V DC/1.0 A Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm 1 P Digital devices are built on the simple concept of repeated application of just a few basic circuits. Operations using these circuits are governed by the rules of Boolean algebra, sometimes also called logic algebra when applied to digital circuit technology. The first experiment introduces all operations with one or two variables used in digital technology. The aim is to verify the laws which apply in Boolean algebra, i.e. those describing commutation, idempotents, absorption and negation. The second experiment demonstrates de Morgan's laws in practical application. The object of the final experiment is to verify the associative and distributive laws through experiment when operating three variables. 163

16 Digital technology Electronics P Combinatorial and sequential circuits P AND, NAND, OR and NOR operations with four variables P Coders, decoders and code converters P Multiplexers and demultiplexers P Adders P Flipflops P Counters P Shift registers 4-bit digital counter (P ) A combinatorial circuit performs operations on multiple digital circuits such that the output variables are uniquely determined by the input variables. A sequential circuit is additionally able to store the states of individual variables. The output variables also depend on the result of preceding events, which is represented by the switching state of flipflops. As an approach to the structure of complex combinatorial circuits, the first experiment applies the understanding of basic operations previously learned to the logical operation of four inputs. Combinatorial circuits for coding and decoding signals are the theme of the second experiment. In this experiment, the object is to assemble a coder for coding decimal numbers in binary form, a corresponding decoder and a code converter for converting binary to Gray code. The third experiment demonstrates how a multiplexer is used to switch multiple inputs onto a single output and a demultiplexer distributes the signals of a single input line to multiple output lines. The fourth experiment investigates half adders, full adders and parallel adders as key components of a computer. The aim of the fifth experiment is to study the function of flipflops. It deals with the various demands on the behavior of these fundamental components of sequential circuits, which are required for assembling RS, D and JK flipflops. The sixth experiment gives the students an opportunity to assemble various synchronous and asynchronous counters. Specifically, these include a binary counter, a BCD counter, a 4-bit counter, a forward-reverse counter and a counter with parallel data input. The final experiment investigates the shift register as a further important function group in data-processing systems. This experiment shows how these components can be used to realize multiplication and division of binary numbers in an extremely easy fashion SIMULOG LS-TTL, P 1 basic logic circuits SIMULOG LS-TTL, extension P 2 switching networks and units Base plate DIN A 4 for SIMULOG LS-TTL Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm Set of 5 connecting leads, 30 cm Regulated power supply, 2 x 5 V DC/1.0 A 1 P

17 Electronics Digital technology P Serial and parallel arithmetic units P P P P Data transfer between registers Serial and parallel logic elements Serial and parallel adders and subtracters Functions of the buffer, latch and accumulator Serial and parallel adders and subtracters (P ) SIMULOG LS-TTL, P 1 basic logic circuits SIMULOG LS-TTL extension P 2 switching networks and units SIMULOG LS-TTL extension E 4 serial and parallel arithmetic units Base plate DIN A4 for SIMULOG LS-TTL Regulated power supply, 2 x 5 V DC/1.0 A Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm Set of 5 connecting leads, 30 cm 2 P In information technology, the hardware executes arithmetic, Boolean and other operations using arithmetic units. The operations can be performed either serially or in parallel. The first three experiments investigate the serial and parallel processing of data in registers, logic elements and adders and subtracters. The final experiment demonstrates the function of the buffer as a bus driver, the latch as a small intermediate storage element and the accumulator as a register which supports arithmetic operations. 165

18 Digital technology Electronics P Digital control systems P P Structure of functional circuits DA and AD converter Setup for measuring reaction times (P ) Digital control units are used increasingly in industrial applications in order to realize periodic processes reliably and without the need for a great deal of complex circuitry. In the first experiment, the object is to assemble functional digital circuits for controlling a traffic light, an LED display with hexadecimal display, a digital clock with decimal display of seconds and an alarm system. The second experiment investigates the function of an analogdigital and a digital-analog converter which allow digital and analog units to be integrated in an industrial open control loop SIMULOG LS-TTL, P 1 basic logic circuits SIMULOG LS-TTL, extension P 2 switching networks and units SIMULOG LS-TTL, extension E 3, digital measurements and control circuits Base plate DIN A 4 for SIMULOG LS-TTL IC-socket, 14 pin, top IC-socket, 16 pin, top Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm Set of 5 connecting leads, 30 cm Set of 5 connecting leads, 50 cm Regulated power supply, 2 x 5 V DC/1.0 A 1 P

19 Electronics Digital technology P Structure of a central processing unit (CPU) P Function of the ALU, CPU timer, RAM und I/O components P Address bus and data bus P Indirect, direct and immediate addressing P Conditional and unconditional jump instructions P Program memory P Examples of programs Structure of a central processing unit (CPU) (P ) SIMULOG LS-TTL, kit C 9 (complete kit) assembly of a central unit Base plate DIN A3 for SIMULOG LS-TTL Regulated power supply, 2 x 5 V DC/1.0 A Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm Set of 5 connecting leads, 30 cm Set of 5 connecting leads, 50 cm 2 P The heart of every information processing system is the central processing unit (CPU). This consists of an arithmetic and logic unit (ALU), a control unit, the registers and the working memory (RAM), as well as the input and output modules. These elements are linked via the bus system. The structure of the CPU is determined mainly by the requirements of the software. The first experiment explores the functions of the individual hardware components of a CPU, while the second experiment investigates the organization of the address and data buses. The aim of the third experiment is to illustrate the difference between indirect, direct and immediate addressing of storage locations in arithmetic and logic operations. The fourth experiment shows how a predefined program sequence can be altered using conditional and unconditional jump instructions. The fifth experiment looks at how to assemble and expand the program memory. Finally, simple program examples are realized in the last experiment. 167

20 Digital technology Electronics P Microprocessor P P P P P P P Signal transmission via the address, data and control buses Program counter and address structure, zero page Data-transfer instructions Rotation and shift instructions Arithmetic and logic operations Program control using jumps, branches, subprogram calls and interrupt processing Application examples Assembly with microprocessor (P ) The microprocessor BP 6502 is used as the basis for the stepby-step investigation of the main structures and functions of a real microprocessor with input/output units, address-bus display and working memory. Here, the special properties of microprocessors are of course taken into account. The first experiment comprises introductory demonstrations on signal transmission via the address, data and control buses. The second experiment illustrates the function of the program counter, which counts one address further each time an instruction is read. In addition, the division of the 16-bit wide addresses into pages and the storage capacity of each page are examined, as well as the special importance of the zero page. The third experiment focuses on the various data-transfer instructions of the processor and demonstrates how each one is used. This is followed in the fourth experiment by the investigation of processing instructions which shift the content of a register one bit to the right or the left, so that a ninth bit, the carry flag, is required to accommodate the carry digit. The aim of the fifth experiment is to perform arithmetic and logic operations on two register contents. The final two experiments illustrate the control of complex programs. Jump instructions enable the creation of a program loop as well as the subsequent return. Branching instructions make it possible to make the program dependent on a condition. Subprogram calls, as the name implies, permit special subprograms to be activated repeatedly from various points in the main program. Interrupt processing enables a defined interruption of the program flow in such a way that the program can be resumed at the same point SIMULOG LS-TTL, kit M 8 (complete kit) microprocessor circuits Base plate DIN A3 for SIMULOG LS-TTL Regulated power supply, 2 x 5 V DC/1.0 A Set of 5 connecting leads, 4 cm Set of 5 connecting leads, 8 cm Set of 5 connecting leads, 15 cm Set of 5 connecting leads, 30 cm Set of 5 connecting leads, 50 cm 3 P