Electronic circuits for all by Elektor

M. A. Shustov, A. M. Shustov

This book contains more than 400 simple electronic circuits which are developed and tested in practice by the authors.

Michael Shustov is a Doctor of Science and has authored 518 publications, including 16 books and 18 inventions.

Andrey Shustov is a Doctor of Electrical Engineering and has authored 24 publications, including 2 books.

ISBN 978-1-907920-65-3

The technical solutions presented in the book are intended to stimulate the creative imagination of readers and broaden their area of thought. This should allow readers to look beyond the horizons of possibilities and use ordinary electronic items in a new way. This book includes new and original radio electronic multipurpose circuits. The chapters of the book are devoted to power electronics and measuring equipment and contain numerous original circuits of generators, amplifiers, filters, electronic switches based on thyristors and CMOS switch elements. Wired and wireless systems as well as security and safety systems are presented. Due to the high relevance and increased interest of readers in little-known or not readily available information, the different chapters of this book describe the use of electronic devices in industrial electronics and for research, as well as new instruments and equipment for medical use, gas-discharge and Kirlian photography.

This book will be useful for both radio amateurs and professionals. Elektor International Media BV

www.elektor.com

LEARN DESIGN

A number of technical devices presented in this book are related to research of the mysteries of the earth, nature and human beings by using radio electronic devices.

ELECTRONIC CIRCUITS FOR ALL ● M. A.SHUSTOV, A. M. SHUSTOV

ELECTRONIC CIRCUITS FOR ALL

M. A. Shustov, A. M. Shustov LEARN DESIGN SHARE

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Chapter 1 • Power electronics

Chapter 1 • Power electronics 1.1 • Barrier-resistor elements – baristors and their application In power electronics, Thyristors and Triacs are known as commutation elements which are switched from a non-conducting state to a conducting state when a voltage is applied to their control electrode. They turn off if their anode voltage approaches zero. Thyristors and Triacs allow the "right" part of a sine wave signal to be cut with adjustable width for further use. Thyristors and triacs have a number of disadvantages: the impossibility of tripping without interrupting the current in them, low operating frequencies, distortion of shape of sinusoidal oscillations, low power factor and low efficiency. Using Thyristors and Triacs in industrial and consumer electronics causes distortion of the sine wave of the supplying voltage due to adding higher harmonics reducing the efficiency of using of electrical energy. The barrier-resistor element (barrier + resistor = baristor) is a switch element of power and analogue electronics, where electrical "Input-Output" resistance changes abruptly from a conducting state to a non-conducting state or vice versa. A change occurs when voltage at the input of the element exceeds a predetermined threshold (barrier). Symbaristor – symmetric baristor – is designed to operate with AC-current. Baristors and Symbaristors allow an AC-current signal to be divided into segments of adjustable width, using them according to the needs of customers: •

By a summation principle – to regulate or stabilize the power consumption of the heating and lighting devices;

•

To use in power supply units for generation of several different output voltages, etc.

Baristors are a "Thyristors vice versa": considering the diagram "Voltage – Time" – for Thyristors and Triacs, switching occurs on the horizontal (time) axis. In the case of baristors, switching occurs on the vertical axis (voltage) axis. This feature of the baristor opens fundamentally new opportunities for its use in communications equipment and power electronics. Baristors are designed to separate signals with amplitude above or below a predetermined threshold value (barrier) set by a user. Such devices, at low level output, should pass the input signal without distortion if amplitude does not reach the threshold (barrier) value. Upon exceeding the threshold (barrier) value, the input signal automatically switches over to pass undistorted at high level output. Baristors (see Figure 1-1 on page 16) can be categorized as: •

Controlled and uncontrolled (with a controlled or uncontrolled threshold value (barrier));

•

AC- or DC-current (asymmetric and symmetric baristors – symbaristors);

•

Single-channel or multi-channel (multi-level, multi-threshold baristors);

•

Switches as ON/OFF/switch-over.

● 15

Electronic Circuits for All The schematic symbols for the main types of the barrier-resistor elements are shown in Figure 1-1. •

High-level baristor – the voltage at its output occurs only in the case when input voltage level exceeds a certain threshold value.

•

Low-level baristor – the voltage is applied at its output until the input voltage level exceeds a certain threshold value. After that the baristor changes its state and turns-off the load.

•

Switching single-threshold baristors – by continuous increasing of the input voltage, the output voltage is initially present at the output of the lowlevel signal. After exceeding a certain threshold value, the input signal is automatically switched over to the high-level output. The I–V curves of the baristor, the shape of input and output signals, and the examples for the application of a baristor in power supply units are shown in Figure 1-1 to Figure 1-8.

•

Switching multi-threshold baristors – with a continuous increase/decrease in input voltage, the baristor output switches are sequentially switched. The input signal passes on the corresponding output of the baristor (see Figure 1-1).

Figure 1-1 Schematic symbols of the main barrier-resistor elements

● 16

Chapter 1 • Power electronics Figure 1-2 on page 17 demonstrates the operation of a baristor. A semiconductor device with an S-shaped current-voltage or "zener diode" characteristic is used as a threshold (barrier) Z-element determining the response threshold of the device, for example, dynistors, thyristors, zener diodes, bipolar avalanche transistors or controlled and uncontrolled semiconductor analogs. If input voltage does not exceed the switching voltage of the barrier Z-element, then its resistance is infinitely high. The low-level voltage is applied to the control input of one of the switch elements; the inverted highlevel voltage is applied to the second input of the second switch element lossless. As a result, the input signal passes through a used (powered on) switch element. When the input voltage exceeds the response threshold, the resistance of the Z-element is abruptly decreased up to a certain final value. This results in an automatic switchover of the switch elements. Figure 1-3 and Figure 1-4 show schematically a baristor and its current-voltage characteristics (CVC) for a certain load resistance Rload. Figure 1-5 to Figure 1-7 demonstrate the use of single-threshold baristors as a part of the power supply to gain on its output a voltage of one or two levels. The practical use of the baristor as a part of the power supply with an adjustable output voltage is shown in Figure 1-8 on page 19. The signal diagrams on the input and outputs of the baristor (Figure 1-4 and Figure 1-7) are shown in Figure 1-9 on page 20.

Figure 1-2 Schematic views of a switching single-threshold baristor

Figure 1-3 Variant of baristor with one threshold

● 17

Electronic Circuits for All

Figure 1-4 Current-voltage characteristics of a switching baristor

Figure 1-5 Transformerless power supply with baristor use

Figure 1-6 Using of a switching single-threshold baristor in a power supply unit

● 18

Chapter 2 • Measuring equipment

Chapter 2 • Measuring equipment 2.1 • Indicators of “phase“ based on modern elements Indicators used for indicating “phase” and high voltage have been well-known for several decades. Usually an indicator contains series-connected screwdriver probes, a current limiter (resistor) with a resistance of 0.47 to 1MOhm and low capacity between supply electrodes, neon lamps and touch-sensitive areas. When a screwdriver is unipolarly connected to the current-carrying “phase” conductor and a finger touches the sensor pad, the neon lamp glows, signalling the presence of high voltage. The voltage that can be controlled by a similar indicator is 90 to 380V, or more rarely from 70 to 1000V at a current frequency of 50Hz. For a long time, neon lamps were considered to be mandatory as an indication element. Indeed, the capacitive current passing from the AC power supply with a frequency of 50Hz and voltage of 100 to 400V through the indication circuit and the human body to “ground” at the human body capacity of about 300pF (experimental estimation by the authors) is 10 to 40µA, which is two orders of magnitude lower than the magnitude of the current required to make LEDs glow. In this connection, LEDs, piezoceramic transducers and other indicators can be used to indicate the “phase” by using special circuits. The value of the power consumed by a neon lamp with continuous light can be estimated as follows: for lamp voltage of 100V and discharge current of 10 to 40µA, supply power is 1 to 4mW. The value of supply power is sufficient to provide LED lighting, however, since it is not possible to provide the required value of current directly, there is a need for transformers which allow for the pulsed glow of the indicator (not continuous) to be obtained with storing a value of the supply power. Such requirements are met by relaxation pulse generators with operation based on accumulation and short-term energy release: periodic charging of the capacitor from a low-current source to the breakdown voltage of the threshold element, and a subsequent discharge into a low-resistance load (LED). The discharge current is sufficient to result in a bright flash of LEDs. Thus, a similar device should contain a storage capacitor with a small leakage current and an operating voltage exceeding the breakdown voltage of the threshold element; the threshold element meets the following requirements: small leakage currents at a voltage lower than the breakdown one and a low resistance during breakdown. Avalanche transistors and their analogs meet such requirements. Figure 2-1 to Figure 2-3 and Figure 2-6 show the circuits of the “phase” indicators based on relaxation generators using avalanche transistors (see Figure 1-72 on page 56). For these transistors, avalanche-breakdown voltage is close to 8V during inverse switching. The indicator in Figure 2-1 on page 66 contains a current limiter, rectifier based on a bridge circuit, and a relaxation pulse generator. The flash frequency of the LED is close to 3Hz at a voltage of 230V: the increase in capacity of a paper or electrolytic capacitor (with a low leakage) leads to an increase in the intensity of flashes with decreasing the frequency of flashes. The minimum voltage that can be detected by a similar indicator is 45V. The frequency of flashes is reduced up to 0.3Hz. For comparison, neon indicators allow voltage to be indicated at not less than 65 to 90V. The indicators in Figure 2-2 and Figure 2-3 use alternative rectifier circuits. The circuits in Figure 2-2 and Figure 2-3 demonstrate the option for the connection of touchsensitive areas to the other elements of the circuit. The device in Figure 2-4 on page 67 is based on the composite avalanche thyristor. In circuit Figure 2-5 on page 67, the pulse generator is based on the analog of an avalanche transistor with a switching voltage (breakdown) 12V.

● 65

Electronic Circuits for All The “phase” indicator in Figure 2-6 on page 67 is based on the bridge RC-circuit with the connection across a diagonally opposite pair of junctions of a bridge (avalanche transistor). The circuit of the indicator in Figure 2-7 on page 67 is also based on the RC-bridge, but it uses two transistors of n-p-n and p-n-p types: when capacitors C2 and C3 are charged to a particular value, the transistors are instantaneously switched from “OFF” to “ON” state. Capacitor C1 is discharged into LED D5 and the process is repeated. To construct “phase” indicators without using any external power supply sources, other types of generators can be used. For example, Figure 2-8 on page 68 shows the indicator circuit with use of a generator based on two transistors of a different structure. Varying the nominal values can lead to frequent, but not so bright flashes of LEDs, or bright but seldom flashes.

Figure 2-1 “Phase” indicator based on the avalanche transistor

Figure 2-2 Simplified “phase” indicator based on the avalanche transistor

Figure 2-3 Simplest “phase” indicator based on the avalanche transistor

● 66

Chapter 2 • Measuring equipment

Literature 1. The Remote Microwave Field Detector. Radioamateur (Belarus). 1992. No. 10. P. 40; No. 11. Pp. 31–32. 2. Ignatenko Yu. Microwave field detector. Radioamateur (Belarus). 1993. No. 7. P. 40. 3. Patent R.F. 2087004. IPC6 G01S 13/04, H01Q 1/38. Transmit-Receive Module. Yu.L. Soloviev. Discoveries. Inventions. 1997. No. 22.

2.9 • Colour-dynamic indication of a signal level Digital and analogue measuring devices are used usually to measure signal level. The latter are complicated and of little reliability with a range of measuring values being usually packed up in 30 to100 degrees of a scale. A drawback of devices with arrow indication is the impossibility of operation in darkness, shaky conditions, in the presence of acceleration, magnetic fields, in changing inclination angle as well as unsatisfactory mass-dimension parameters and etc. For dynamic indication of a signal value at a “more – less” level, either achromatic or quasichromatic light-emitting indicators (incandescent lamps, light-emitting diodes and etc.) can be used. It is possible to separate up to 10 degrees of light intensity change in a short interval of time visually in terms of the gradation of brightness, see Figure 2-25. But to define a signal level confidently and to relate it to some basic magnitude is not directly possible.

Figure 2-25 Graduation strips of gray and colour tones The situation changes considerably when transformed to colour indication of a signal level (colour-dynamic indication). The principle of operation of the colour-dynamic measuring devices is based on visual representation of a measured magnitude in the form of colour shade. An untrained eye of an average human is known to be able to distinguish up to 300 colour shades, but a trained eye, up to several thousands. Hence, a changing a colour of indicator included on the output of a measuring device can help one distinguish not 30–100 degrees of the scale, but by a factor higher – more than 300, see Figure 2-25 and Figure 2-26. However, the problem of correlation of each indicated colour shade to the level of a measured signal in this case remains.

● 79

Electronic Circuits for All In measuring bridges, the exact value of a measured quantity can be calculated in terms of relation of known elements of the counterbalanced bridge. In the devices with colourdynamic indication [1, 2] in quantitative defining, the level of a measured signal next to a light resumption screen of the device a stripe of colour range with a scale – index of correspondence of each measured value, for example, of voltage to the colour shade (such as litmus paper) is placed as an element of comparison, Figure 2-25 on page 79. To widen the range of measurements and its extension the removable stripes of spectrum including different sub range of the colour scale can be used. The extension of the colour shades of transitions and delimitation of the colour scale being used can be made using a graphics editor on a PC. The alternative, but not an expressed variant of definition of a measured signal level in terms of its colour shade is a comparison of the lighting colour of two colour-dynamic measuring devices. The former controls the value of an unknown (controlled) signal, the latter is supplied from a precision regulated source, see Figure 2-27. The technique of measurement fully corresponds to the method of balance bridge measurements (on reaching the identity of colour shades of the colour-dynamic indicator light), see Figure 2-27.

Figure 2-26 Example of mixing the two different colour tones in different ratio

Figure 2-27 Comparison of two voltages by using color balance of two LED optical radiation sources For synthesis of colour scale by mixing colour components of two or three controlled sources of optical radiation while changed the level of input signal the following converters can be used:

● 80

Chapter 3 • Generators

Chapter 3 • Generators 3.1 • Forward-bias sensors in controlled high frequency generators The methods to control the frequency of the generator used as converters of a measured value into a frequency are well known and include the effect on an R, L and C frequencycontrol element; on the active element of a generator or power supply source. The sensors based on active elements with an N-shaped current-voltage characteristic (CVC), tunnel diodes, lambda diodes and their analogs usually contain a current source, active element and a frequency-control element (LC-circuit) with a parallel or series connection. As such the generators are critically sensitive to bias voltage and operate in a limited range. Forward-bias semiconductor sensors used, for example, in the voltage/frequency and current/frequency converters operate in a forward-bias region of a current-voltage characteristic and have a high conversion conductance. In particular, the equivalent resistance of a semiconductor forward-bias converter depends exponentially on the applied voltage. Since the sensors operate at low voltages (fractions of volts), they are optimally combined with the generators based on the active elements with an N-shaped current-voltage characteristic (tunnel diodes, lambda diodes, etc.). Figure 3-1 shows a generalized circuit of a controlled high-frequency generator based on the active element with an N-shaped current-voltage characteristic and a forwardbias semiconductor sensor. The resistor R limits the current through the non-linear elements connected in parallel: the semiconductor sensor, resistance and capacity of which depends on the applied voltage, and an active element with an N-shaped currentvoltage characteristic. The operating frequency of oscillation is determined by the parallel oscillation circuit. When a semiconductor sensor is affected by, for example, the change in a voltage, current, or temperature, the conversion of a measured value into current and then in frequency, its resistive-capacitive characteristics are changed. The modulation of a generated frequency takes place due to the redistribution of currents.

Figure 3-1 Generalized circuit of a controlled generator based on the active element with an N-shaped current-voltage characteristic and a forward bias semiconductor sensor

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Electronic Circuits for All

Figure 3-2 Practical circuit of a controlled high-frequency generator based on the tunnel diode (radio adapter of a serial-type telephone line)

Figure 3-3 Practical circuit of a controlled high-frequency generator based on the tunnel diode powered by a current source of any polarity (radio adapter of a serial-type telephone line)

Figure 3-4 Practical circuit of a radio microphone based on the tunnel diode] Figure 3-2 and Figure 3-3 show the practical circuits of the controlled high-frequency generators based on tunnel diodes (radio adapter of a serial-type telephone line. The forward-biased junction of a semiconductor diode is used as a sensor. Frequency modulation is conducted mainly due to changes in dynamic resistance of the sensor. The capacitive resistance of a semiconductor sensor is much lower than its directcurrent resistance for a high-frequency component. A semiconductor diode stabilizes the operating point of the tunnel diode by simultaneously controlling oscillation frequency.

● 120

Chapter 3 • Generators

3.15 • Pulse oscillator based on a CMOS switch The pulse oscillator in Figure 3-45 is constructed using a CMOS switch, namely elements IC1.1 and IC1.2 in microcircuit CD4066. When the oscillator is switched on, both switch elements of the microcircuit are open. Capacitor C2 is charged through resistor R5 up to a voltage at which switch IC1.1 is switched on. Power supply voltage is applied to the resistive divider R1–R3; capacitor C1 is charged through resistor R4, resistor R3 and part of potentiometer R2. When the voltage across its positive plate reaches the switch-on voltage of the switch IC1.2, both capacitors will be discharged, and the charge-discharge process will be repeated periodically. Potentiometer R2 allows the value of a “start” voltage to be changed to charge capacitor C1 and, consequently, the frequency of the generated pulses to be changed in the range from several to tens of Hz.

Figure 3-45 Pulse oscillator based on a CMOS switch A resistance load or indicator of the oscillator operation, for example, a light-emitting diode with a current-limiting resistor (680Ohm) can be connected in parallel with the chain of resistors R1–R3. A second pulse oscillator can be constructed using the unused elements of microcircuit IC1.3 and IC1.4. This device can be used as an oscillator controlled by the power supply voltage in the range of 5 to 15V. The frequency of pulses generated is increased with decreasing power supply voltage.

3.16 • IR pulse oscillators Infrared pulse oscillators are often used for security alarms and in remote control radio electronic application. In order to maintain battery resources, IR pulse oscillators should provide short powerful (tens to hundreds of mA) current pulses through a light emitting diode (LED) with a repetition frequency between Hz and kHz.

● 145

Electronic Circuits for All The best way to construct such devices is to use relaxation pulse oscillators based on elements with an S-shaped CVC. Such oscillators are used for the power supply of semiconductor lasers, when there is a need for short current pulses through the n-p junction of a laser diode. Figure 3-46 shows the IR pulse oscillator circuit based on composite avalanche transistor T1 and T2 (Figure 1-72 on page 56). The transistor operating in avalanche mode (Figure 1-72 on page 56), is used as a nonlinear element. The pulse repetition frequency is determined by constant R1(C1 + C2); pulse duration is determined by constant R2(C1 + C2). The maximum current through light-emitting diode LED1 is determined by the expression:

I max =

U pow − U LED1 − U ecV2 R3

where Upow is the power supply voltage; ULED1 is the voltage drop across a light-emitting diode; UecT2 is the emitter/collector voltage drop for transistor T2 at current Imax. The series-connected light-emitting diode or parallel connection of a series-connected lightemitting diode and current-limiting resistor can increase the output power of the device, if necessary. Due to the fact that the average current consumed by the device (mA) is almost two orders of magnitude lower than the maximum current passing through a light-emitting diode, output transistor T2 is not heated. The device can operate in a power supply voltage range from 8V (avalanche breakdown voltage of transistor T1) to the breakdown voltage in the collector junction of transistor T2 (tens to hundreds of volts, depending on the type of transistor). The IR pulse oscillator, constructed using the circuit in Figure 3-46 controlled the receiver at a distance of more than 50m without additional optical devices at a power supply voltage of 24V, an oscillation frequency of 1kHz and three light-emitting diodes. The oscillator generates pulses with a frequency of 2 to 3Hz for the nominal values shown in the circuit (Figure 3-46). When security alarm loop B1 is opened (disconnection of capacitor C1), pulse frequency is increased by an order, which leads to the triggering of a security alarm device. A security alarm circuit can operate by the infrared beam breaking method. Figure 3-47 shows an IR-pulse oscillator circuit based on the analog of an injection fieldeffect transistor (T1 and T2). In contrast to the device in Figure 3-46, the oscillator operates at low voltages: the upper limit of power supply voltage is limited by the limiting voltage of the power supply of a field-effect transistor. The lower limit of the power supply voltage is limited by values ULED1 and UecT2 (>3V).

Figure 3-46 IR-pulse oscillator based on an avalanche transistor

● 146

Chapter 4 • Amplifiers

Chapter 4 • Amplifiers 4.1 • Main characteristics of operational amplifiers One of the most important characteristics of operational amplifiers (OA) is the frequency dependence of a transmission (amplification) coefficient, or an amplitude-frequency characteristic (AFC). For illustration purposes and usability, the frequency characteristics of the amplification coefficient modulus OA are usually represented in the coordinates (Figure 4.1), and the following rule is met: lg|K| + lgf = const.

This dependence can be described by the equation of the straight line: y = –ax + b, where = y lg= K ampl ; x lg f . Then lg K ampl = −a lg f + b. The a and b coefficients can be determined using the following equalities:= y lg K ampl = 0;= x lg= f 0. In the general case

a =

lim lg K ampl lim lim lg K amp lg K ampl ; b lg K ampl . or= = lim lg f

 lg f 1 − lg f lim 

  . Only the ideal AFC OA can be 

described by the straight line with the coordinates given in Figure 4-1. It should be noted that this characteristic is considered to be a frequency dependence of the transmission coefficient modulus. In fact, the AFC OA is different due to various structural reasons (Figure 4-1).

Figure 4-1 Ideal (limiting) and actual amplitude-frequency characteristics of the operational amplifier

4.2 • Standard connection circuits of operational amplifiers An operational amplifier (OA) is an integral direct current amplifier, the parameters of which are dependent on the properties of negative feedback in the circuit. Based on the

● 165

Electronic Circuits for All OA, it is possible to construct devices designed for amplification, comparison, limitation, processing, selection or filtering of different signals, as well as the other radio electronic equipment. An ordinary OA is an amplifier with two inputs and one output. Table 4-1 provides the basic circuits for OA connection, when low-level signals are applied from voltage or current sources to the amplifier input. Table 4-1 Circuits and properties of idealized devices based on OA Scheme

Transmission factor, K

Differential amplifier

U out = ( U in1 − U in2 )  R1 R3  =    R2 R4 

Voltage amplifier

R2 +1 R1 U out = KU in

Voltage source inverter

−

R2 R1

U out = −

R2 U in R1

Voltage repeater

U out = U in

● 166

R2 R1

Chapter 4 • Amplifiers Table 4-3 Comparative characteristics of electronic devices based on N- and S-type negatrons CVC of an active element

Uwork, V

Iwork mА

Pcons, mW

Fmax, МHz

N-shaped

Fractions units

Units … tens

~10

>1000

S-shaped

Units ... hundreds

Fractions

~10

<0.2

For the stable operation of the amplifier based on a negavaristor, its operating point should be located approximately in the middle of the region with negative dynamic resistance. The load line, the inclination angle of which is determined by the ratio E1/Rload = I1, should intersect the CVC only one time (Figure 4-13 on page 176), line B, point 1. If the load line (for example, line A, Figure 4-13 on page 176, points 1, 2 and 3) intersects the CVC at two or three points, the amplifier will be transformed into a generator of relaxation or sine-wave oscillations. The first case (amplification) corresponds to the condition Rload < |R–|, the second case (oscillation) corresponds to Rload > |R–|, where Rload is the load resistance; R– is the differential resistance of a negavaristor for the given region of the CVC [4]. The general formula for establishing the relationship between the voltage-currentfrequency characteristics of negavaristors (negatrons) can be given by: 2

f N R work.S  U work.S   I work.N  4 = =  =   =  10 , fS R work.N  U work.N   I work.S  U where R work. = work. . I work. Standard circuits of the amplifiers based on negavaristors are shown in Figure 4-15 on page 177. They differ in the method for connection of a useful signal source. A feature of double-pole amplifiers, which include negavaristors, is that their inputs and outputs are equivalent (interchangeable). On the one hand, this is a positive feature, since it allows reversed amplifiers to be constructed. On the other, it is impossible to directly increase the number of amplifying stages for such amplifiers. The operating point of amplifiers is determined by resistive dividers R1—R4. AC load resistance Rload is connected in parallel with a negavaristor. For the amplifier circuit in Figure 4-15a, the resistance of a Rosc signal oscillator (source) is connected in parallel with a negavaristor and connected in series with it for the circuit in Figure 4-15b. Considering the method for connection of the oscillator, the total resistance of the load and resistive divider R1–R4 should be less than the differential resistance of the negavaristor (R–). Examples of negavaristors with an N-shaped CVC are shown in Figure 4-16 to Figure 4-19, and the negavaristors with an S-shaped CVC are shown in Figure 4-21 to Figure 4-23 [1, 5–9]. The program of circuit simulation (Multisim) was used to model the operation of electronic devices based on negavaristors. A 2-volt zener diode model was used as zener diodes D1, Figure 4-17 and Figure 4-19, in the circuits of the lambda diode and tunnel diode analogs. The results obtained in modeling the operation of devices (Figure 4-15 to Figure 4-23), are summarized in Table 4-4 on page 176. The transmission coefficient corresponds to a frequency of 1kHz, and bandwidth corresponds to 0.707 (–3dB). To simplify the amplifier

● 175

Electronic Circuits for All circuits, the following assumptions are made: Rosc = 0, Figure 4-15b (this resistance is connected in series with the resistance of a negatron), C1 = Cosc = Cload = 0. Table 4-4 Characteristics of negatron amplifiers Fig No.

E,V

U0,V

I0,uA

R1,R2, Ohm

R3,R4, Ohm

Rload, kOhm

С2,uF

Bandwidth, Hz

Transmission coefficient,dB (once)

Amplifier based on elements with the N-shaped CVC 4.16 4.15b

7,0

2,741 129,4

100 (47%) 388,08

5500 5500

200

3,0

0,11...70000 32,53(42,3)

4.17 4.15b

3,0

2,161 1934

100(68%) 27,91

100

1,0

1,7…22000

11,65(3,82)

4.18 4.15b

3,0

2,536 2789

20(43%)

33,2 8

1,0

2,0...15000

30,15(32,2)

4.19 4.15b

4,0

2,868 5219

100(70%) 20,155

3 8

100

1,0

1,3…2400

35,15(57,2)

4.19 4.20 4.15b

4,0

2,744 8030

100(67%) 24,398

0 8

17,66

100pF

Resonance 323.1kHz

94,65(54000)

Amplifiers based on the elements with an S-shaped CVC 4.21 4.15b

22,0

2,056 41,04

10kOhm (75%) 5kOhm

220kOhm 75 8

1,0

60…13000

31,48(37,5)

4.22 4.15b

6,0

1,614 93,72

0 8

50kOhm 8

1,0

72…7800

32,98(44,5)

4.23 4.15a

30,0

9,144 69,21

50 (69%) 16,481

R7 50 300kOhm 8

1,0 C1—10,0

30…13000

35,22(57,6)

The analysis of the experimental data shows that the tuning of the amplifier requires careful selection of a power supply voltage for the device, sometimes with an accuracy of several mV (resistive divider R1–R4). The increase in the amplification coefficient of each device, Table 4-4, leads to the simultaneous decrease in its frequency range (highfrequency region). The low-frequency region (low-frequency limit) is entirely determined by the nominal values of a capacity (capacitor C2) and load resistance Rload. Excluding these capacities allows DC amplifiers to be constructed. The effect of the capacities C1, Cocs, Cload (units ... tens of pF) on the operation of amplifiers in the low-frequency range can be neglected. The increase in the amplification coefficient by more than 20 to 40dB can lead to the self-excitation of the amplifier. The instability of the power supply voltage and ambient temperature significantly influence the operation of the amplifier.

Figure 4-13 Current-voltage characteristics of N-and S-type negatrons (a and b) and the load line for the amplifier based on the S-type negatron (c)

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Chapter 5 • Filters

Chapter 5 • Filters 5.1 • LC- and RC-filters with an adjustable bandpass Examples of circuit realizations of high and low frequency filters, band-pass and resonant filters with smooth operating characteristics (width, edge and passband height) are shown. The problem with the creation of modern filters remains the complexity of provision with smooth adjustments of key parameters: band passes and positions and transmission coefficient. Examples of implementation of LC- and RC-filters with gradually adjustable parameters are further presented. Figure 5-1 shows the LC-filter of the operational amplifier, which notably allows adjustment of the (smooth and in wide ranges) bandpass at preservation of transmission coefficient in pass-band frequencies. Simultaneously, the device allows varying levels of output signal (coefficient of filter transmission). The bandpass of the filter is adjusted by potentiometer R4. The transmission coefficient is adjusted by R3.

Figure 5-1 LC-filter with an adjustable bandpass Under the condition L1 = 1Hn, R1 = 1kOhm, R2 = 100kOhm, R3 = 2kOhm, R4 = 500Ohm, C1 = C2 = 1uF, IC1 LM741H, by adjusting potentiometer R4 it is possible to change the bandpass of the filter at the maximal transmission coefficient of 34.0dB (50 once) in the band of frequencies at the level –3dB from 80 up to 14500Hz (short-circuited potentiometer R4) and up to 34.7dB in the band of frequencies at the level –3dB from 115 up to 700Hz (the maximal value of resistance of potentiometer R4). A simpler variant of performance of the LC-filter with smooth adjustment of the width of a resonant band is given in Figure 5-2 on page 184. At adjustment of potentiometer R4 (L1 = 100mHn, R1 = 1kOhm, R2 = 75kOhm, R3 = 2kOhm, R4 = 500Ohm, C1 = 1uF, IC1 LM741H) there is a tuning of the bottom transmission cut and narrowing of the filter bandpass. The family of peak-frequency characteristics of the filter at tuning of potentiometer R4 is given on Figure 5-3 on page 184. The transmission coefficient of the filter varies over a wide range: from 0 by kmax ≈ 20lg(R2/R1), dB, by the adjustment of potentiometer R3. The resonant frequency of the filter is defined from the expression

f rez =

2π LC

, Hz, who L – in Hn, C – in F.

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Figure 5-2 LC-filter with smooth adjustment of the width of a resonant band

Figure 5-3 The family of peak-frequency characteristics of the LC-filter at tuning of potentiometer R4: 1) 0; 2) 50Ohm; 3) 100Ohm; 4) 200Ohm; 5) 500Ohm (The resonant frequency is 50Hz) If the resonant LC contour in the scheme Figure 5-2 is replaced with the condenser, it is possible to obtain a low pass filter (Figure 5-4). At variation of an adjusting element (potentiometer R4), a smooth tuning of the boundary frequency of the filter transmission takes place.

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Chapter 5 • Filters

Figure 5-27 The amplitude-frequency response rejection LC-filter (1 – SA1 is disconnected; 2 – SA1 is connected)

Figure 5-28 Amplitude-frequency response rejection RC-filter (1 – SA1 is disconnected; 2 – SA1 is connected)

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Electronic Circuits for All The RC-filter, in comparison to the previous one, allows effective suppressing handicaps signal. Thus, on a rejection frequency of 504.0kHz, the maximum suppression of handicaps signal, depending on quality of filter adjustment can reach 83 to 90dB at the total weakening of other frequency signals of about 40dB (Figure 5-28 on page 197). At short circuit of switch SA1 (shutting-off the filter), the total weakening of signals is 22 to 23dB, which can be compensated by the introduction of an additional cascade of strengthening.

Literature 1. Bunimovich S., Yaylenko L. The technique of single-sideband amateur radio communication. Moscow: Publishing house of DOSAAF, 1970. 312 p.

5.5 • Gyrator filter based on electronically tuned transistors A gyrator is an electronic circuit that transforms a combination of RC-elements and an amplifier into an equivalent LR-circuit to imitate an inductance coil. The resonance frequency of a gyrator (Figure 5-29) is gradually tuned by potentiometer R6 in the range of 90 to 130kHz for the 26dB transmission coefficient in the range limits with a maximum at the frequency of 100kHz (41dB). The input and output of gyrators are equivalent, since the device imitates a conductance coil.

Figure 5-29 Electronically tuned gyrator filter in the range of 90 to 130kHz

5.6 • Multichannel valve quasi-filter A frequency multiplex is used in measuring and communication devices and for measuring and analyzing frequency-amplitude spectra. The use of a quasi-filter valve device (Figure 5-30 on page 200), allows the problem of frequency multiplex to be solved. Such filters can operate in the frequency range of tens of Hz to several MHz. The quasi-filter device (Figure 5-30 on page 200) includes: input signal amplifier (1); pulse shaper/limiter based on the Schmitt trigger or comparator (2); frequencyto-voltage conversion unit (f/U) (3); output level regulator (R5); poly-comparator line switching circuit of output switches in proportion to the amplitude of an input signal (microcircuit IC1);voltage regulator (R1, D1); circuit for setting the response limits

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Chapter 6 • Electronic switches

Chapter 6 • Electronic switches 6.1 • MOS analog of thyristors In 1955, the Bell Telephone Laboratory (USA) published an article [1] that first described the construction of a thyristor, namely a four-layer semiconductor device with a controlled S-shaped VAC (Figure 6-1). Since then, the diversity of thyristor and triac structures has expanded considerably. Classical thyristors are widely used due to natural selection in the practice. Along with their undeniable advantages, thyristors have undeniable disadvantages: low input resistance, unsatisfactory frequency characteristics, significant voltage drop for the open device, etc. The problem concerning the low input resistance of thyristors was solved by developing thyristors which were a combination of a field-effect transistor, including MOS transistor, and thyristor [2, 3]. The equivalent circuits of similar thyristors are selectively shown in Figure 6-2.

Figure 6-1 Equivalent circuit of a classical thyristor

Figure 6-2 Equivalent circuits of MOS thyristors Below, Figure 6-3 on page 204 shows the several circuits for the synthesis of thyristor structures, using MOS elements. The circuits are not ideal, but the further improvement can serve as a starting point for the development of thyristors with improved properties. Figure 6-3(1) shows an example of a thyristor based on a CMOS switch element in the input circuit. The disadvantage of this thyristor is a low operating voltage (up to 15V) and a significant voltage drop across an open element of up to 3V. The advantage of the thyristor is a high input resistance (about 1MOhm) and increased response. To reduce the voltage drop

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Electronic Circuits for All across the open element, a modern modification of the CMOS microcircuit can be selected to operate at a power supply voltage of less than 2V.

Figure 6-3 MOS analogs of thyristors Figure 6-3(2) shows a thyristor based on two MOS transistors with P- and N-channels. A thyristor differs in that it has two control electrodes. To switch the thyristor on, the input of CE1 is momentarily connected to the common wire, or a control short signal with a voltage of over 4.1V is applied to the input of CE2. To switch off the thyristors, it is usually enough to switch off the power supply for a moment, or apply a voltage of lower 4.0V (0 to 4.0V) at the input of CE2 for a moment. Also this input can simply be connected to a common wire. When the load resistance is 750Ohm, the current through the load is 9.6mA. At a power supply voltage of 12V, the current through the load does not exceed 12uA when the thyristor is in the off-state. Figure 6-3(3) demonstrates that the thyristor is also based on two MOS transistors with P- and N-channels but it is initially in the on-state. To switch off the thyristor, the control signal with a voltage of 0 to 2.5V is applied at the input of CE1, or this input can be simply connected to the common bus. To reconnect the thyristor, the control signal is applied to the input of CE2 (this input is connected to the common wire) or the power supply is disconnected for a moment. The initial on-state of this thyristor analog is due to the inequality of initial resistances for the drain-source channels of transistors T1 and T2 when the device is switched on. The structure of a thyristor in Figure 6-3(4) is close to the classical structure of the MOS thyristor shown in Figure 6-2 on page 203, but it has an additional control input of CE2. The minimum voltage is 1.35V to switch on the thyristor at the input of CE1.

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Chapter 7 • Communication

Chapter 7 • Communication 7.1 • Wire telegraphy device A wire telegraphy device (Figure 7-1) is designed to study the telegraph alphabet, as well as wire telegraph communication between two or more users. A double-wire line is used for communication between users; one of the wires can be presented by pipes or even the surface of the earth. The device does not need a switch and operates as follows: In the initial state, if there is no need for self-monitoring of an operator, switches SB1 and SB2 are closed. Pressing for example the telegraph switch S1 leads to current from battery GB1 passing through diode D1 and a communication line, and is applied to transistor T2. The transistor is opened and switches on the elements of visual and sound indication, LED2 and HA2 respectively. At the same time, transistor T1 is closed; there is no light or sound indication on the transmitting side. The corresponding processes take place when switch S2 is pressed: When switches S1 and S2 are pressed simultaneously, the device is blocked and the signal does not pass from counter partner to counter partner. In order to provide self-monitoring, the transmission of telegraph signals, the button SB1 (and/or SB2) is pressed. In this case, pressing switches S1 or S2 is accompanied by sound and light signals on the receiving and/or transmitting side. Sound emitters with built-in oscillators, for example HCM1212X, were used as the sound emitters HA1 and HA2 at an operating voltage of 12V in the voltage range of 8 to 15V. When a device uses batteries (accumulators) designed for example, lower voltage, it is necessary to adjust resistors R2 and R3, as well as use sound emitters designed for operation at a lower voltage, for example HCM1206X or HCM1205X.

Figure 7-1 Wire telegraphy device

7.2 • Wire telephony device The wire telephony device in Figure 7-2 on page 226 is designed for double-wire telephone communication between two or more users. The device does not need a switch, since it consumes minimum current due to the collector reverse current of transistors T1 and T4 when buttons S1 and S2 are not pressed.

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Electronic Circuits for All When button S1 (transmission) is pressed, current from the battery GB1 passes through a microphone, diode D1, a communication line and reaches the receiving side. It opens transistor T3, passes through the transient electrolytic capacitor C2 and reaches the base of transistor T4 that amplifies the current which is applied to the sound emitter BF2. At the same time, transistor T2 is blocked; there is no reverse acoustic feedback. Similar processes occur when the button S2 is pressed. When buttons S1 and S2 are pressed simultaneously, the device is blocked, and the signal does not pass from counter partner to counter partner. In the frequency range of 0.2 to 10kHz, the transmission coefficient of the amplifiers based on the transistors T1 and T4 is changed from 25 to 27dB. The device can operate when a battery is discharged up to 3V. Carbon microphones of handsets are used as microphones BM1 and BM2. Electronic components of devices, including buttons S1 and S2 can also be placed in these handsets.

Figure 7-2 Wire telephony device

7.3 • Three-channel double-wire communication device The device in Figure 7-3 and Figure 7-4 is designed for three-channel double-wire communication between several users. Three-program broadcast loudspeakers are usually used for the reception of messages. Three frequency channels are used for communication: a low-frequency channel (sound frequency range) and two high-frequency channels of 78 and 120kHz. An oscillator is based on transistor T1, (Figure 7-3 and Figure 7-4), whose oscillation frequency or switching-off is determined by switch SA1. The oscillator uses Colpitts oscillatory circuit. The modulation signal, received from the output of the microphone amplifier is connected in the open collector circuit of transistor T1 through isolation transformer Tr1 (Figure 7-3 and Figure 7-4). When a low-frequency signal is applied, there is amplitude modulation of the signal generated. The modulated signal is applied to the communication line through a separation capacitor. The operating frequency of the oscillator is altered due to the change in capacities. In the low-frequency range, the oscillator is switched off. For the oscillator in Figure 7.3, the inductance coil of the oscillation circuit is short-circuited. For the circuit in Figure 7.4, the transistor of the oscillator is switched off. In this case, the low-frequency signal is applied directly to the communication line through the transformer and electrolytic capacitors C1 and C7 (Figure 7-3, or C1 and C6, Figure 7-4). Operating frequencies of the oscillators are determined by selecting capacitors. The light-emitting diode LED1 indicates the on-state of a device and simultaneously stabilizes the operating point of the oscillator transistor.

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Chapter 8 • Security and safety systems

Chapter 8 • Security and safety systems 8.1 • Personal protection alarms Personal protection alarms are designed for individual protection against criminal activity. Such devices can be used in security alarm systems, for safety of vehicles and also can be mounted in brief and suitcases. The base element of circuit Figure 8-1 contains a sub hertz range oscillator and voltage controlled oscillator. The terminals of the module are represented as follows: Figure 8-1: 1 – is the positive power supply voltage; 2 – is the output; 3 – is the negative power supply voltage (common wire); 4 – is the sound characteristic device; 5 – is the timer. Figure 8-2 on page 258 shows a personal protection alarm with the use of p-n-p output transistors. The current consumed by the device is 450mA at a supply voltage of 9V. The device operates as follows: after a short pressing of button SB1, capacitor C1 is charged from the power supply source and opens composite transistors T1 and T2 to switch on the alarm. When the capacitor is discharged, the transistors are closed, and the alarm is switched off. The duration of alarm sound is determined by the RC elements and is 2 to 3 minutes: the volume and duration of the alarm sound are higher at an increased voltage. In waiting mode, the device practically consumes no power and consequently does not need a switch (the current in the no-signal state is several uA). The peculiarity of the circuit in Figure 8-2 on page 258 is that the behavior of sound signals is changed in time, which is caused by the smooth closing of transistors T1 and T2. The alarm sound is not discontinued when the power supply is switched off for a short time. The device in Figure 8-3 on page 258 is constructed using n-p-n output transistors. The alarm is also switched on after short closing the contacts of the SB1 button. The circuit can also use button SB2 that is pressed and held for more than ten seconds to switch the alarm on that is switched off after only 2 to 3 minutes. This peculiarity allows the alarm to be used (Figure 8-2) in security alarm systems. Switch SA1 allows the behavior of sound signals to be changed: from a periodic howl to two-tone sound signals.

Figure 8-1 Basic element of a personal protection alarm oscillator

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Electronic Circuits for All

Figure 8-2 Electric circuit of the personal protection alarm

Figure 8-3 Security alarm based on the personal protection alarm

● 258

Chapter 9 • Electronics for industrial purposes

Chapter 9 • Electronics for industrial purposes 9.1 • Gas- and temperature-sensitive relay Gas and temperature-sensitive relay circuits can prevent the occurrence or development of fire-hazardous situations during the operation of gas supply systems. The operation of gas-sensitive sensors is based on the reversible reaction between some hydrocarbons and thin films of metal oxides (usually SnO2). Temperature-sensitive relays can use semiconductor forward-biased sensors, the voltage drop of which is proportional to ambient temperature. Four-terminal devices are commonly used as gas-sensitive sensors: two terminals are connected to the heating element; the other two terminals are terminals of a gassensitive tin dioxide layer. When current passes through the heating element, a tin dioxide layer is heated up to the operating temperature. The change in the environment (interaction of a sensor layer with molecules of hydrocarbons: methane, ethane, propane, butane, alcohols, etc.) results in a reversible change in the electrical resistance of the sensor. Therefore, gas-sensitive relays can be constructed using simple methods of controlling electrical resistance of the sensor. Figure 9-1 shows one of these circuits. Comparator IC1 is used as a comparison device that compares voltage drop across resistive divider B1 (sensor) and R2 and the voltage drop across the adjustable resistive divider of the comparison arm (potentiometer R3). The load of the comparator is light-emitting diode indicator LED1. A relay that switches on an alarm or sound signal oscillator can be used as a load of a comparator.

Figure 9-1 Electrical circuit of a hygro-sensitive relay

Figure 9-2 Electrical circuit of a temperature-sensitive relay

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Electronic Circuits for All A heating element can be made of thin nichrome or other wire. Small metal film resistors, without lacquer coatings, for example, the resistors designed for surface mounting, can be used as heating elements. The SnO2 based sensor has an electrical resistance of about 2MOhm in the absence of a controlled gas medium and 170 to 200kOhm in the presence of a gas medium (ethyl alcohol vapor). The thermal electrical relay (Figure 9-2 on page 277), is constructed using a similar circuit (Figure 9-1), and allows the medium temperature rise to be controlled near a semiconductor sensor. To increase the sensitivity of a circuit, several diodes (temperature sensors) can be connected in series. To ensure that in the case of an emergency situation, the load of the comparator is not connected, but disconnected, the connection of comparator inputs (terminals 2 and 3) should be interchanged.

9.2 • Gradient relay Gradient relays are the devices which respond to the rate of change in the controlled parameter. These relays are used to control time-varying values. The operation of gradient relays can be explained by Figure 9-3 to Figure 9-9. In the initial state, the ratio for resistances of divider R1/sensor is close to 1. The input voltages of the comparator are the same, and the gradient relay is in signal waiting mode (ready mode). Let us assume that the resistance of the sensor is changed. When voltage is reduced across divider R1/sensor (Figure 9-4 to Figure 9-6), the voltage at one input is changed almost instantaneously. The voltage at the other input is also changed with a delay due to the use of the RC chain. For the operation of the comparator it is sufficient that voltage difference at its inputs is several mV. Considering the small voltage difference, the capacitor can be assumed to be linearly charged (or discharged) (Figure 9-3). Therefore, when the resistance of the sensor is changed, the gradient relay will start operating at the moment of time t1 (Figure 9-3). If the resistance of the sensor is not changed or returns to the initial level and stabilized, the equilibrium state is reestablished at the inputs of the comparator and the gradient relay is switched off.

Figure 9-3 Dynamics of transient processes during the discharge/charge of a capacitor (linear approximation for small time intervals)

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Chapter 10 • Electronics in household use

Chapter 10 • Electronics in household use 10.1 • Output stages of a light-dynamic device Light-dynamic (colour-dynamic) devices are designed for aesthetic visual perception of musical compositions. Conventional colour-music installations contain 3 to 4 channels with a frequency division multiplexing: low, medium and high sound frequencies. When a sound signal (playing a musical composition) is applied at the input of a colour-music installation, the output of this installation, the filament lamps of different colors, for example, red (low frequency), green (medium frequency) and blue (high frequency) are iridescent according to the amplitude of a musical composition and its frequency "color”. Thus, the light-dynamic (colour-dynamic, colour-music) installations are simple frequency-amplitude analyzers with a visualization of output signals. Thyristors or triacs are used to control lighting of sufficiently powerful light sources (filament lamps with a capacity of tens to hundreds of W). A disadvantage of simple colour-music installations is clear definition in the total lighting intensity of a screen or scene, especially in the case when a colour-musical composition has a large dynamic volume range. Devices for balancing the light fluxes (Figures 10.1 and 10.2) can be used to enrich the color range of a musical composition, increase its aesthetic potential and reduce the difference in total lighting intensity of light sources. The first device (Figure 10.1) has optoelectronic isolation with input circuits and can be used as an attachment for available colour-music installations. The light-emitting diode of the optocoupler A1 should be connected through a current-limiting resistor (and, if necessary, a diode to provide the "correct" polarity of a control signal) to the one of the stages of a colour-dynamic device, considering that voltage drop across the light-emitting diode should not exceed the maximum permissible peak level.

Figure 10-1 Single-channel output stage of a light-dynamic device with balancing of light fluxes and galvanic isolation

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Electronic Circuits for All

Figure 10-2 Three or more channel output stage of a light-dynamic device with total balancing of light fluxes The device in Figure 10-2, can be easily constructed, but the elements of its design are not electrically isolated from the power supply circuit. Thus, the colour-music installation should be galvanically isolated from the source of a sound (musical) signal and the control elements of the installation should have a reliable isolation preventing contact with the human body. Colour-music attachments of transformers, microphones or optocouplers used at the input usually provide this isolation. The lamps of the additionally obtained channels can be painted in the colors which are different from the basic ones, for example, in orange, yellow or blue. A 3–4 channel colour-music installation can use 3 to 4 separate cascades for balancing of a light flux, or one common cascade, in accordance with Figure 10-2. The power and nominal values of resistor R4 (Figure 10-1), and R2, R4, R6 (Figure 10-2), are determined by the power supply voltage of the installation (mains voltage) and the type of triacs or thyristors used (no less than 2W).

10.2 • Colour-controlled light-emitting diode night lamp with the mains power supply A light-emitting diode emitter (Figure 10-3) with an adjustable emission spectrum can be used for the lighting of instrument scales, orientation in the dark, a low intensity night light, an indicator for switching on equipment, a part of garlands, etc. An emitter contains a minimum number of elements and can be installed in the plug of an electrical appliance, or in the base of a neon or light lamp. An emitter consists of a resistive voltage damper (time-setting resistors), diode rectifiers with variable load current and two relaxation pulse oscillators based on avalanche transistors loaded by multi-colored light-emitting diode emitters. Resistors R1 and R3 are used to drop voltage that is excessive for the operation of oscillators. When using resistive voltage dampers, current consumed by the device does not exceed 1mA (the device consumes no more than a one-tenth of a W from the mains). Voltage-dropping resistors R1 and R3 are a part of time-setting resistors. Diode rectifiers D1 and D2 are used for separate power supply of the device oscillators. The relaxation pulse oscillators are based on transistors operating in avalanche mode (Figure 1-72 on page 56). The transistors are inversely connected in the "open" base mode.

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Chapter 11 • Medical devices and equipment

Chapter 11 • Medical devices and equipment 11.1 • Device for the detection and control of biologically active points The effect of electric current on biologically active points (BAP) is widely used to aid human health. At these points, skin resistance is known to be significantly decreased, and electrical capacity substantially increased. Considering these factors, a circuit of the device was developed to detect BAPs and exert an effect on them (Figure 11-1 on page 338). The device is designed for the scanning and detection of biologically active points, the primary diagnostics of diseases and subsequent (if necessary) therapeutic effect on them by electric current pulses. The circuit is based on an asymmetric multivibrator (relaxation pulse oscillator). Capacitors C2 to C3 provide positive feedback. Search electrodes are connected in parallel with capacitor C1. In the initial state (the search electrode circuit is open), the circuit generates highfrequency (close to ultrasonic) oscillations which are not reproduced by a loudspeaker. The oscillation frequency is determined by the parameters of potentiometer R3 and capacitor C1 that can be represented by a tuning capacitor. When detecting BAP, one of the search electrodes is placed in the hand of a patient and the second is moved (scanning) over the skin. When search electrodes are connected to the human body for scanning detection of BAPs, the circuit designed for positive feedback of the multivibrator through capacitors C2 and C3 is closed through the part of a human body where an equivalent circuit represents a set of resistive-capacitive elements. When the positive feedback circuit is closed through BAPs, in the vicinity of which the resistance and capacity of skin are significantly different from normal values, the oscillation frequency is significantly decreased. This allows biologically active points to be identified with certainty. When the electrode is placed at BAPs, the frequency of the oscillator is significantly reduced, allowing BAPs to be identified with certainty. The detection method can be used when a patient is near a metal sheet (object) to which one of the search electrodes is connected; the second electrode can be represented either by the electrode or, for example, the finger of a doctor holding the second electrode in the other hand ("pseudo-monopolar" detection of BAPs due to capacitive coupling). The load of the multivibrator is resistor R4 (Figure 11-1). The signal generated by the multivibrator is amplified by the power amplifier and applied through the matching transformer to the electrodynamic head (sound indicator of BAPs) and the electrodes which exert active effect on biologically active points. For diagnostics of pathological processes and the documental processing of experimental results, a digital frequency meter or other recording device can be connected to the output of an oscillator. BAPs can be affected by two (three) methods: •

using search electrodes in all the modes mentioned above;

•

using additional winding of a transformer;

•

using the collector of transistors T1 and T2.

In the latter cases, there is no need to remove search electrodes from a patient (using biological feedback, "self-adjustment" of the body to the optimal exposure mode), or the

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Electronic Circuits for All search electrodes can be closed to set the required current frequency by potentiometer R3 (and the amplitude is set by resistor R4, replacing the resistor with a variable resistance and connecting its wiper with the base of transistor T3).

Figure 11-1 Electrical circuit of a device for detection of biologically active points to exert an effect on them The device can also be used as a universal electrical circuit to study the dynamics of processes developing in living organisms, create combined measuring "human-device" systems, and as pulse oscillators for tuning radio electronic equipment and more.

11.2 • Circuits for the diagnostics of biologically active points At present, there are a lot of devices and methods used for the diagnostics of biologically active points. Controlling the properties of these points, in particular, direct current resistance provides the opportunity to monitor change in internal organs, determine the effectiveness of taking medications and medical procedures, optimize them, and observe the dynamics of disease and recovery with quantitative assessment of deviation from the normal and recovery state. One of the most reliable and obvious methods for assessing the pathology of internal organs is the R. Voll method [1] and its modifications [2, 3]. In accordance with this method, the change in internal organs can be controlled by indirect data (change of electrical resistance) when measuring electrical resistance of certain BAPs, where electrical resistance correlates to the state of particular internal organs. It is believed that for a "normal" state of a person, electrical resistance values between points and a common electrode should be within a particular range of acceptable values. The more the electrical resistance of a controlled point (organ) exceeds the acceptable value, the more the pathological process is developed. For example, resistance above normal levels corresponds to the development of disease processes, the extinction of vital forces, and hypotonia. The decrease in resistance below a normal level corresponds to the development of inflammatory processes associated with acute development disease. The range of acceptable values for each person is strictly individual and determined by body type and electrical conductivity of tissues.

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Chapter 12 • Electronics in the study of unusual phenomena

Chapter 12 • Electronics in the study of unusual phenomena 12.1 • Paradoxical experiments and their explanation Paradoxical phenomena or events are a fertile area for scientific discoveries, inventions and sensations. For example, works [1, 2] reported that inventor A.A. Melnichenko managed to defy the laws of nature and obtain electrical energy from the world space, giving nothing in return. In his experiments, A.A. Melnichenko connected a capacitor in series with the winding of an AC induction motor, then, after selecting the capacity of a capacitor, he received a resonance. As a result, the induction motor, designed to operate at 230V, started operating at a lower voltage of about 110V and, according to the "correct" calculations of the innovator, increased the power by two times. Applying a voltage converter operating at a higher frequency, an office fan with a 100W motor started operating using four flat batteries [1]. A.A. Melnichenko believes that the next stage in the development of new power industry is the creation of a more advanced device with increased release of energy. He believes that for this purpose, it is sufficient to cool an induction motor to the temperature of liquid nitrogen ... to obtain superconductivity. According to his calculations, a modern transformer pillar could provide power of tens of MW [2]. Meanwhile, the "Melnichenko effect" is easily explained by simple arguments (Apparently, due to these arguments, the interest of those who showed particular attention to the inventor's work rapidly waned). From electrical engineering textbooks it is known that Ohm's law for a serial RLC-circuit (Figure 12-1 on page 379), can be written in the form [3]:

U 2

R + (X L − X C ) 2

, where U is voltage; I is current; R, XL = ωL, Xc = 1/ωC is the active,

inductive and capacitive resistance of circuit elements; Ω = 2πf is circular frequency and F is the frequency of electrical oscillations. If there is no capacitor, Figure 12-1a: I =

R + (X L − X C ) 2

It is obvious that if an additional capacitor is connected in series to the RL-circuit, the current will be increased in the circuit. The dependence of the current in the RLC-circuit and the values

cos φ =

, when changed the reactance of the capacitor, are shown in

R + (X L − X C ) 2 Figure 12-2 on page 379.

Figure 12-2 shows that increasing capacity of the capacitor leads to the fact that the current in the circuit is first increased (before the resonance at XC = XL) and then starts decreasing. Value cosφ is synchronously changed: during resonance cosφ = 1, the value of current is maximal in the circuit. At the same time, load voltage is increased by Q times, where Q is the quality factor of the RLC-circuit determined by the ratio XL/R. This excess voltage can result in the breakdown of the insulation of winding loops and damage an appliance. Thus, the additional connection in series with the induction motor winding of an extra capacitor can trigger the induction motor even for significantly low mains voltage, but these processes are in the frameworks of ordinary ideas.

● 377

Electronic Circuits for All The effects which cannot be predicted by theory and practice and can be used in technical objects for applied purposes are as follows: dimensional (scale) effects, time effects, border effects, non-additive effects, cumulative effects, etc. Individual exotic effects and phenomena which stay within the bounds of traditional ideas, but are explained by other ideas, sometimes involving controversial theories or hypotheses, violating the «Occam's razor» principle, should be referred to that mentioned above. Such ideas, of course, can also serve as an engine of progress, but distract from the development of scientific directions. To illustrate incorrect explanation of individual physical effects and experiments, the following typical or well-known examples are given: The interesting and informative experiment is described in the works of A.V. Chernetsky and Yu.A. Galkin (self-generating discharge of Chernetsky-Galkin) [4]. In accordance with Figure 12-3 on page 380 the device contains a capacitor, an active resistive load (electric lamp) and electric discharger. All elements of the circuit are connected in series through the winding of the power transformer to AC mains. When using short-circuited discharger FV1, current is low in the load circuit, and the light of the electric lamp is glimmer (Figure 12-3). If the electrodes of the discharger are opened (Figure 12-4 and Figure 12-5 on page 380), after separation, for example, with a micrometer screw to obtain a stable discharge, the lighting intensity of the electric lamp notably increases. According to the ideas of the inventions authors [4], the energy of physical vacuum is converted into electric power. A.V. Netushil and P.V. Ermuratsky [5], analyzing the experiments of A.V. Chernetsky and Yu.A. Galkin [4], showed that when an electric discharge was excited in a discharger, a complex-shaped current of a non-sinusoidal form at a frequency of 50Hz (it was shown in Figure 12.3) passed through a series-connected circuit consisting of a capacitor and an active resistive load. Figure 12-3 to Figure 12-5 show the dynamics of electrical processes occurring in the circuit under study and the oscillograms of signals registered at different points, including frequency-amplitude characteristics (simulation with the use of Electronics Workbench). A negatron (diode thyristors) at a switching voltage of 100V (Figure 12-4) and 300V (Figure 12-5) is used as an imitator of an electric discharger. The current in the electrical circuit (Figure 12-4 and Figure 12-5), the shape of which is described by the Fourier series contains numerous high-frequency components. Since the capacitive resistance of the capacitor is inversely proportional to its capacity and current frequency, the value of current passing in the circuit (Figure 12-4, Figure 12-5), significantly exceeds the value of current passing in the circuit shown in Figure 12-3 on page 380. Among the following paradoxical experiments in the field of electrical engineering, let us consider the «superconductor» of engineer S.V. Avramenko [6]. The experimental setup of S.V. Avramenko (Figure 12-6 on page 381), contains a stepup transformer, (Figure 12-6b), powered by alternating current at a voltage of 60V and a frequency of 3kHz. One of the terminals in the secondary high-voltage winding of the transformer is connected to a single-wire transmission line in the form of a thin (15μm in diameter) tungsten conductor, the length of which is tens of centimeters to tens of meters; the second terminal of the secondary winding is not connected to other elements of the electric circuit. The "Avramenko plug" is connected to the line and presented by a high-voltage rectifier in the form of two series-connected high-voltage semiconductor stacks, to the middle point of which a line is connected, and capacitor C1 (capacity is

● 378

Index

Index A

batteryless 60 beeper 142 begonia sheet 372

accumulators 225

bell 264

acoustic gradient relay 282

beta-gamma-radiometer 111

AC output 42

biolocation effect 383

actinic exposure 362

biological feedback 361

active element 29

biologically active points 337, 338

additive triangular signal 150

biological systems 356

adjustable filters 185

biorhythms 356

adjustable voltage 45

bipolar avalanche transistors 17

aero-ion indication 389

bipolar generator 62

alternating voltage 42

bipolar pulse 144

amplification coefficient 169

bipolar transistors 83

amplitude-frequency characteristic 165

bipolar voltage 47

analog timing devices 289

bipolar voltage stabilizer 42

antenna-electrode 71

blocking generator 100

antimigraine 344

blown-fuse indicator 55, 61

antimigraine oscillator 349

bridge circuit 65

anti-phase addition 152

bridge diode 253

argirosis 304

bridge RC-circuit 66

argyria 304

bridge rectifiers 49

asymmetrical multivibrator 24, 337

brightness achromatic 87

attenuating capacitor 218

broken base 56

attenuation 152 automatic solar charger 316 automatic stabilization 50 autotransformer converters 34 avalanche breakdown 56, 95 avalanche transistor 62, 72 axis rotation angle 100

C capacitive energy storage 21 capacitive relay 282 capacitor 21 capacitor tester 96 car alarm system 259 carbon microphone 149, 162, 226 cascade connection 288

balance 151

charged plate 22

balanced-bridge circuit 107

chess clock 330

bandpass 183

class-D amplifier 172, 174

baretters 50

clock generator 333

baristor 15, 17

CMOS 68, 104, 144

barium titanate 315

CMOS switch 212, 214

â&#x2014;? 391

Electronic Circuits for All CMOS/TTL 41

differential radio frequency 297

coded locks 260

diode 21

coincidence circuit 221, 260, 264

diode bridge 69

collector circuit 105

diode matrix 38

collector-emitter resistance 51

diode rectifiers 302

colloidal silver 304

diode resistive attenuator 255, 256

colour-dynamic 301

diode signal switches 252

colour-dynamic frequency 133

direct current generator 52, 76, 81

colour-dynamic indication 79

direct voltage 42

colour heals 350

discharging circuit 97

colour-music 302

double-level 47

colour range 90

drain-source channels 204

colour scale 80

drain-source resistance 71

colour scale oscillators 354

duplex communication 232

colour therapy 351

dynamic heads 259

Colpitts circuit 29, 31

dynamic indication 79

Colpitts oscillator 128

dynamic resistance 121

common busbar 60

dynamization 310

commutative inrushes 50

comparator 277 compensation 151 complex switching 218 compound transistor 51 constant-voltage 45 controlled signal 80 control pulse shaper 222 current integral 331 current limiter 65 current-voltage characteristics 17

electret microphone 162 electric air cleaner 321 electric field indicators 72 electric plug 381 electrolytic capacitor 38, 61, 65 electromagnets 48 electronic biolocator 385 electronic telegraph 238 electronic thermometer 107 electroskin resistance 349

electro vacuum devices 326

Darlington transistor 333

emission wavelength 234

DC circuits 69

emitter-indicator 86

DC source 100

energy channels 340

dead time 68

energy-saving alarm 272

decoupling 58

exclusive-or 222

detector of HF signals 282

exposure cell 371

dialing code 268

dielectric spacer 272

â&#x2014;? 392

ferrite ring 33

M. A. Shustov, A. M. Shustov

This book contains more than 400 simple electronic circuits which are developed and tested in practice by the authors.

Michael Shustov is a Doctor of Science and has authored 518 publications, including 16 books and 18 inventions.

Andrey Shustov is a Doctor of Electrical Engineering and has authored 24 publications, including 2 books.

ISBN 978-1-907920-65-3

This book will be useful for both radio amateurs and professionals. Elektor International Media BV

www.elektor.com

LEARN DESIGN

A number of technical devices presented in this book are related to research of the mysteries of the earth, nature and human beings by using radio electronic devices.

ELECTRONIC CIRCUITS FOR ALL ● M. A.SHUSTOV, A. M. SHUSTOV

ELECTRONIC CIRCUITS FOR ALL

M. A. Shustov, A. M. Shustov LEARN DESIGN SHARE