Millman Theorem
The usual methods for the solution of the currents in or the potential differences across the elements of a network involve a direct application of Kirchhoff's laws. This involves setting up the mesh currents and then equating the sum of the potentials around any closed loop equal to zero. The number of independent loops that must be chosen must equal the number of unknown currents to be found. The resulting algebraic equations are then solved, ordinarily by using determinants, for the desired...
P j eib dt p e sin e cog e
The effective resistance of the diode circuit is defined by the relation Re g s 16-26 P 9 - sin 8 cos 0 j That is, the effective resistance in parallel with the capacitor due to the loss in the diode circuit is equal to firp. A plot of is also contained in Fig. 16-6. By combining Eqs. 16-26 with 16-16 , an expression for the equivalent resistance that shunts the diode input circuit is possible. This is Re _ Re rp _ tan 6 9 R rp R 9 sin 9 cos 8 This expression is plotted as a function of R rp in...
T Arv
The shortcoming of these voltmeters is that the input impedance during the conducting portion of the cycle is different from that during the nonconducting portion of the cycle. This difference arises from the fact that the diode consumes power during the conducting portion of the cycle. This effect is precisely that discussed in Sec. 16-3, where it was shown that the effective input resistance to the diode Re R 2ri and is approximately R 2, where R is the load resistance. Ordinarily R is so...
A Xuz
Abnormal glow discharge, 28 Ammeters, electronic, 480 electrometer tubes, 481 Amplification, voltage see Amplifier, voltage-gain Amplification factor, measurement of, 45 numerical values for several tubes, 492 . tetrode, 23 triode, 17 Amplifier, audio-frequency, anode-follower, 108 . comparison with cathode follower, 111 gain, 109 input admittance, 110 output impedance, 109 broad-band, anode-follower see Amplifier, anode-follower cathode-follower see Amplifier, cathode-follower compensated,...
Average Constantcurrent Characteristics
Physically, it almost entirely encloses the plate. Because of its design and disposition, the screen grid affords very complete electrostatic shielding between the plate and the control grid. This shielding is such that the grid-plate capacitance is reduced by a factor of about 1,000 or more. However, the screen mesh does not interfere appreciably with the electron flow. The reduction of the grid-plate capacitance is a very important improvement over the triode, and this matter will be...
O 1
12-5. A type 852 triode has the following ratings as an r-f power amplifier and oscillator key down conditions without modulation per tube D-c plate voltage 3,000 volts D-c grid current 15 ma approx The tube is operated under rated conditions in a tuned-plate oscillator, operating at a frequency of 1 megacycle. Determine the following e. Resonant impedance of tank circuit. . Grid leak required. g. Mutual inductance between grid and plate coils. Assume that the maximum grid voltage is equal to...
R Gtu
owing to grid clipping, and Ecc , gt p _ Ecc Ehl on T2. must be such that eci is slightly positive and ec2 is negative. If now a positive signal is applied to both grids simultaneously, there will be no appreciable action in T1 but T2 will begin to conduct. This will reduce the grid potential on Tl, which reduces the tube current, setting off a regenerative action that continues until Tl ceases to conduct and T2 is fully conducting. The transfer is effected in precisely the same manner as that...
kkyv r
This expression for the gain is independent of the frequency, since no reactive elements appear in the circuit. Since each of the elements is resistive, the phase angle between input and out- Rg put voltages is constant and equal to 180 deg. L-F Region. At the low frequencies Fig. 5-5. The 1-f equivalent circuit the effect of Cg is negligible, and Yc of the RC amplifier. may be made zero. The effect of the coupling capacitor C becomes very important. The equivalent circuit under these...
Info Aeh
this reduction is considerably less than the corresponding reduction of the two-stage single-tuned amplifier. This arises from the fact that the amplification or selectivity curve of the double-tuned amplifier has steeper sides than that of the single-tuned circuit and with successive stages drops away less rapidly than for the single-tuned case. In particular, an ideal amplifier with a rectangular response curve would show no band-width reduction with the addition of successive stages. 10-5....
Special Sweep Generators
It may be shown that the deflection of the electron beam in an electro-magnetically deflected cathode-ray tube is proportional to the field strength of the deflecting field. The field strength is proportional to the current passing through the deflecting coil, if saturation is avoided. Consequently, if it is desired to deflect the electron beam linearly with time, the current through the coil must be increased linearly with time. When the end of the sweep is reached, the electron beam must be...
Info Gbj
Fig. 18-20. A biased blocking oscillator. Fig. 18-20. A biased blocking oscillator. The duration of the pulse, i.e., the length of the conducting period r, depends upon the capacitor C and upon the characteristics of the transformer. For a given transformer, C is the most important circuit element, larger values of C being accompanied by longer pulses. For example, a certain transformer, when used in the circuit of Fig. 18-20, yielded pulses which could be varied from approximately 0.2 to 20...
Info Ucb
If the two tubes have identical characteristics, then Fig. 18-7. The potential and current wave forms at various points in a symmetrical multivibrator. Rg Rqi Rg Ci C2 Eq. 18-9 reduces to The expressions given by Eqs. 18-8 to 18-10 apply to multivibrators having a low repetition frequency, since they do not take stray capacitances into account. At the higher repetition frequencies, the following more precise equation should be employed instead of Eq. 18-8 3 This expression is also subject to...
ffTTTim
Fig. 15-4. The frequency spectrum of a complex wave. 15-2. Square-law or Small-signal Modulation. Amplitude modulation may be produced by impressing two sinusoidal voltages of different frequencies in a nonlinear circuit. The van der Bijl modulator is one of the earliest methods, although it is seldom used at the present time. This modulator depends for its operation on the curvature of the transfer characteristic. A circuit of this modulator is given in Fig. 15-5. The Modulated output e Ec...
Tuned Voltage Amplifiers
Tuned voltage amplifiers are used in those cases in which it is desired to amplify a relatively narrow band of frequencies centered about some designated mean or carrier frequency. Voltages whose frequencies lie outside of this range are undesirable and should be rejected. The use of tuned networks accomplishes this, as it is possible to adjust the tuned network so that the impedance falls steeply to low values outside of the Pig. 10-1. The three basic tuned-amplifier circuits a single-tuned,...
L Wdv
diode within 0.1 per cent over the range from about 8 to 150 jusec. 19-12. The Linear-sweep Delay. The linear-sweep delay circuit incorporates a feed-back linearizing circuit to achieve a linear saw-tooth wave. This particular circuit will be discussed in some detail in Chap. 20. A comparison is then effected between the potential, and hence the setting of a potentiometer, with that of any desired position on the linear saw tooth. Although the voltage comparison is accomplished in a different...
Info Nhx
19-13. Pulse Generators. It is ordinarily not possible to distinguish between a narrow gate and a pulse, particularly since the two may be generated in the same manner. A sharp distinction is hardly necessary, but one might perhaps distinguish between them on the basis of the ultimate purpose of the signal. Another distinguishing feature might be based on the time duration of the signal. There are, however, certain methods available for generating very narrow pulses with reasonably sharp rise...
Ek
Fig. 20-5. The wave shape of the output in a simple glow-tube sweep generator. Curve a is for a supply voltage of 600 volts curve b is for a supply voltage of 135 volts. The amplitude of oscillation is the same in both cases. The amplitude of the oscillation equals the voltage difference Ed Ec. Such simple glow-tube circuits may be used for frequencies of 1 cycle every few minutes to frequencies well up in the a-f range. The wave shape of the resulting saw tooth is dependent upon the magnitude...
Info Yto
Fig. 1-8. Photocurrent as a function of illumination for a PJ-22 vacuum phototube, and a PJ-23 gas-filled cell. A significant comparison of the output from two phototubes, one of the vacuum type and the other of the gas-filled type, other characteristics of the tubes being the same, is contained in Fig. 1-8. Note that the photocurrent for the vacuum phototube is a linear function of the illumination, whereas that for the gas-filled cell shows deviations from the linear at the higher...
Info Kxa
_ 2,245 X 319 QK_ Pl -g- 357 watts _ 2,245 X 319 QK_ Pl -g- 357 watts n 35M40 X 100 81 P 1 - 0.81 X 440 83.5 watts P 0.9 X 755 X 0.025 17 watts ber of factors are important in such a design, and it is desirable to examine the influence of these. The important factors that are involved in the enginering design of a class C amplifier are the following 1. The peak space current that should be demanded of a given tube. This is usually controlled by the values of etmm and ecm , since the total...
Armstrong Modulator Block Diagram
e Ec sin wct cos co,, com t cos wc m 17-54 Note specifically that, if ma d,i, the only essential difference between the a-m and the p-m waves is in the relative phase of the carrier and the side bands. Evidently for small values of dd, if the side bands of the a-m wave can be shifted by 90 deg with respect to the carrier, a p-m wave results. It is immaterial, of course, whether the phase of the carrier or the phase of the side bands is shifted in order to achieve the p-m waves. The process here...
J Kbv
Fig. 15-2. Frequency spectrum of a sinu-soidally modulated wave. 03C 03m, which is equal to the difference between. the carrier and the signal frequency. This component is known as the lower side band. A plot of the frequency spectrum of the modulated wave is illustrated in Fig. 15-2. It should be emphasized that the foregoing is not a mathematical fiction, as it is possible by means of appropriate filters to extract the frequencies in the spectrum. In fact, the features of transmission of...
Info Hrf
R2 cooC2R2 RzyCii and noting that in the neighborhood of resonance The gain ratio Eqs. 10-28 to 10-20 then becomes which has the same form as for the direct-coupled connection Eq. 10-14 . The band width of this amplifier is, following the same reasoning as that which led to Eq. 10-16 , The optimum value of M is not of much importance, owing to practical limitations. This follows from Eq. 10-24 , which shows that for pentodes, with the corresponding large values of rv, the value of M would be...
V Ufo
Fig. 18-24. Typical wave form of the suppressor voltage in a pentode van der Pol relaxation oscillator. Fig. 18-24. Typical wave form of the suppressor voltage in a pentode van der Pol relaxation oscillator. flows in the screen circuit. The capacitor charging current now flows through R3 and the combination of R2 in parallel with the screen-cathode path resistance, and the potential of the suppressor begins to rise. This brings the action to the point at which the considerations began, and the...
Problems 1
2-1. Plot lb vs. Eb of the 6H6 diode see Appendix B on log paper. From this plot determine the quantities k and n in the expression lb kE . 2-2. The anode current in a type 5U4G diode with 54 volts applied between the plate and cathode is 200 ma. What is the required potential for a current of 100 ma The tube operates under space-charge conditions. 2-3. Suppose that the FP-400 tube is operating under rated filament power input see Prob. 1-2 . The operating temperature is 2700CK anode diameter...
C Fwo
Capacitance, interelectrode, numerical values for several tubes, 492 . pentodes, 63 tetrodes, 62 triodes, 58 Capacitor filters see Filter, rectifier, capacitor Carrier suppression, 325 Carrier wave, disappearance of, in frequency modulation, 369 suppression of, 325 Cathode, directly heated, 4 indirectly heated, 4 inward-radiating, 4 mercury as, 28 oxide-coated, disintegration, 31 emission, 3 work function, 3 photoelectric, 4 power for heating, 64 thermionic see Thermionic cathodes Thermionic...
Info Xwx
Fig. 7-20. The wave shapes at several points in the circuit of Fig. 7-19. Fig. 7-21. The equivalent circuit of Fig. 7-19 during the time that T1 is cut off. 7-3. Clamping Circuits. Because no conductive path exists whenever any asymmetrical wave form is passed through a capacitor or a transformer, the average ordinate of the wave form must assume a zero potential. This is another way of saying that the d-c component of a wave form that is passed through a capacitor or a transformer must...
Untuned Power Amplifiers
The voltage amplifiers discussed in Chaps. 5 and 6 are designed to increase a voltage signal from a low level to one which is adequate for operating some low-power circuit. Such amplifiers are generally operated in class A since the amplification is to be accomplished without distortion. Pig. 9-1. The schematic and equivalent circuits of a simple series-fed power amplifier. Pig. 9-1. The schematic and equivalent circuits of a simple series-fed power amplifier. A power amplifier serves to supply...
H Fpw
For a circuit for which the linear time is to extend for 100 sec, the deviation becomes The initial potential drop that appears in the plate potential does not appear in these equations but represents the contribution to the initial plate current by the charging current required to charge the tube and wiring capacitances. If the circuit is modified as illustrated in Fig. 19-26, a control is possible to the upper and lower potential limits between which the linear saw tooth traverses. In this...
Gas Tubes
2-14. Electrical Discharge in Gases. There are two important types of discharge in gases that play roles in electron tubes. One of these is the glow discharge, and the second is the arc discharge. The glow discharge utilizes a cold cathode and is characterized by a fairly high tube drop and a low-current-carrying capacity. The voltage drop across the tube over the operating range is fairly constant and independent of the current. The arc discharge is characterized by a low voltage drop and a...
Current Generator Circuit For A Pentode
Fig. 20-13. A negatively Pig. 20-14. The output-voltage wave form from biased saw-tooth generator. the sweep generator of Fig. 20-13. If the tube is normally biased negatively so that no current flows through it, then upon the application of a positive gate the potential across the capacitor will fall from the value Ebb to the value determined by the drop across the tube Eb and the drop across the resistor Ri2, if one is used to limit the current through the tube. The generator circuit is given...
E volts Ea volts C if R ohms
a. Calculate the frequency of oscillation. b. Calculate the amplitude of the generated waves. c. Plot the wave shape of the generated waves. Assume that the flyback time is zero. 20-2. Design a thyratron relaxation saw-tooth generator to yield a substantially linear saw tooth having a peak amplitude of 25 volts, with a recurrence frequency of 1,000 cps. Specify reasonable values of Ebb, Ecc, R and C, and give reasons for your choice. 20-3. Derive an equation for the potential across capacitor C...
S Vwr
Fig. 14-19. A simple voltage-regulator circuit. ally such special tubes are not necessary, as it is quite possible to achieve the same ends by including a d-c amplifier in the circuit in such a way that slight changes in output potential are amplified before being applied degeneratively to T. These circuits are used extensively and a detailed analysis will be given below. 14-9. Electronic Voltage Regulators Basic Considerations. The design of electronically regulated power supplies has become...
L Mzl
Fig. 6-19. The equivalent circuit of a typical stage of the resistance-coupled amplifier of Fig. 6-18. For an appreciable voltage gain, the parallel combination of Rn and Rci Rg2 should be large compared with rp, and Rg2 should be large compared with Rcl. This will necessitate the use of a large bias voltage. Direct-coupled amplifiers are used extensively as the amplifier in a circuit, the grid exciting source of which has a very high internal resistance or which is capable of supplying only a...
Info Iwa
It is easy to show that m is related to rv and gm by the expression This is obtained by setting Aib 0 in Eq. 2-13 and then using the definitions of Eq. 2-14 . The variations of these parameters for a fixed value of plate potential for the 6C5 tube are shown in Fig. 2-9. It is noticed that the plate c resistance varies over rather wide limits, being very high at zero plate current, and approaches a constant value at the higher plate currents. The transconductance varies from a very small value...
Comparison Of The Cathode And Anode Follower
6-8. Direct-coupled Amplifier.4 It is possible to build a type of cascaded amplifier without reactive elements and, in principle at least, secure a very broad band amplifier. The voltage gain of such an amplifier does not depend on the frequency, at least to a first approximation, except for the effect of tube and wiring capacitances at the higher frequencies. It might appear that such amplifiers would find very widespread use because of these desirable characteristics. However, such amplifiers...
R Vhq
Radio communication, amplitude modulation, 320 frequency modulation, 386 modulation essential for, 320 single side band, 357 Radio frequency amplifiers see Tuned amplifiers Reactance, primary, effect on amplifier operation, 77 transformer, leakage, effect on amplifier operation, 79 Receiver, automatic volume control in, 355 for amplitude-modulated waves, 212 for frequency-modulated waves, 386 frequency modulation, 386 discriminator, 387 limiter, 386 selectivity of, 192, 206 single side band,...
Info Bsd
Fig. 7-29. The output wave form from a negative clamping circuit for an applied positive gate pulse. Fig. 7-29. The output wave form from a negative clamping circuit for an applied positive gate pulse. Fig. 7-31. Clamping circuit which establishes the reference voltage E volts. Fig. 7-31. Clamping circuit which establishes the reference voltage E volts. cathode, an electron current flows and the cathode-grid resistance is very low, whereas when the grid is made negative with respect to the...
PROBLEMS Vxx
13-1. A type 5U4G is connected in a half-wave circuit to supply power to a 1,500-ohm load from a 350-volt rms source of potential. a. On a plate characteristic of the tube, plot the load line, and from this find the dynamic curve. b. Obtain a plot of the output-current wave shape for a sinusoidal applied voltage. c. Estimate the value of the plate resistance rP from the static characteristic at four different values of current 50, 100, 150, 200 ma . Use the average of these as the rp of the...
Info Byf
Fig. 18-5. The wave shapes of the current through and the potential across capacitor C i during its charging period. Fig. 18-5. The wave shapes of the current through and the potential across capacitor C i during its charging period. the potential 61 across the capacitor C1 will vary between and En,, where Eb2 is the voltage across T2 when this tube is conducting. The voltage and current conditions have the forms illustrated in Figs. 18-5 and are governed approximately by the equations The...
V Bid
It follows from this that the required LC product for a specified ripple r is given by Note also that, to the approximation that the impedance between A 2 and B2 is simply Xc , the critical inductance is giyen by Eq. 14-37 , as for the single-section unit. 14-6. Il-section Filter. The use of a II-section filter provides an output potential that approaches the peak value of the a-c potential of the source, the ripple components being very small. Such a filter is illustrated in Fig. 14-15....
Info Jbq
Fig. 20-23. The use of a diode in the plate circuit to reduce any d-c shift and to maintain the feed-back gain. constant potential Em, charges toward a continually increasing potential, the extent of the increase being such as to compensate very nearly for the potential across the capacitor. Thus the current through the circuit remains constant, with a consequent linear potential across Ci. Of course, if amplification is provided before applying the output across the capacitor Ci to the grid of...