JPS58159008A - Sound recording and amplifying circuit - Google Patents

Abstract

PURPOSE:To prevent an abnormal operation in the event of an excessive input signal, by limiting a driving current applied to a variable impedance element in an ALC circuit. CONSTITUTION:A signal inputted to a terminal 1 is inputted to an amplifier A through a variable impedance element E. The amplifier A amplifies the input signal by specified gain, and outputs it from a terminal 5. In case the input signal is large, the variable impedance element E is controlled in accordance with magnitude of voltage of a portion which exceeds reference voltage, so that the input signal becomes small. Voltage for controlling the variable impedance element E is limited before the variable impedance element E is saturated. In this way, it is prevented that the output signal is distorted, by preventing that the variable impedance element E is driven excessively.

Description

[Detailed description of the invention]

The present invention relates to a recording amplifier with LC for a tape recorder. In a general tape recorder, if an excessive signal is input from a microphone or the like during recording, the recorded signal will be distorted, so an ALC circuit is provided to apply ALC to the single-ball sound signal. The present invention provides a low frequency amplification circuit having a Machiya impedance element directly connected to the current, a reference wIL ratio source that can be compared with the output voltage of this low wave amplification circuit, and a reference voltage line of C. A comparator circuit for comparing the voltage with the output voltage of the low frequency amplification circuit 411i1, and a drive circuit for receiving the output aj of the comparator circuit and driving the variable impedance Th element. The purpose of this invention is to limit the drive current of the drive circuit described above, thereby preventing abnormal operation when an excessive input color code occurs in the LC operation, and realizing normal operation of the recording amplifier with ALC. . The following is an example of an embodiment based on the present invention using a Jk high surface.
satiti. 1! The reason is 1. The present invention can be used as a LC for stereo tape recorders.
This is the circle IIb factor when applied to the *& circuit of an attached recording amplifier. The MULC appendix child intensifier shown in Figure 91 has a variable impedance T.
The child wings are directly connected to the first stage input! A reference voltage source 1 that can be compared with the output voltage of the low-frequency amplification circuit A of the wings of 11 and the low-frequency amplification circuit A of each skeleton, and a reference voltage generated from the IP voltage source B6ζ And above! c A comparative soft circuit C which compares the output voltage of each low frequency amplification device, and increases the output signal of the comparative soft circuit C. A drive path p that drives the Kasame impedance element M, and I
It is composed of a circuit for reducing excessive noise when the power source is turned on. In each case, at least one diode Ds*C4a DB a D is inserted in series in each emitter.
Composed by vaQ 8

【are doing. Stone 1 @ 6 * This is a one-month old recording field width amplifier with ALC for stereo tape recorders, and it has two low frequency amplifier circuits A and two impedance elements each. They are called the left channel and right channel. ]-1ζ, (March) power supply terminal 1 (13 and (
9] are signal input terminals for the left channel and right channel, respectively, and the signal StS of the microphone with the signal source resistance jig is
(1) μ is the other positive terminal for the left channel and right channel, respectively, and LL is a negative Fi resistor with a voltage equivalent to the input impedance of the next stage. , and the output signal is taken out via the coupling condensers c@, c, -J and (2) are the low frequency increases of the left channel and right channel, respectively.
Terminals for contacting the negative layer of the mm, C1 and C6 are the terminals for the negative layer of the mm.
The capacitors INF and INF are respectively T-shaped resistors that perform AC negative feedback together with the resistors Its of the low-frequency amplifier circuit, and determine the AC voltage gain of the low-frequency #II width circuit A. . 2) is the ripple filter terminal, and Kosiden 41
(:s & * 974 L/resistance 111 is installed at the power supply terminal (1) to remove the pull portion during the voltage applied to the IC voltage. C8 is a terminal provided in the drive circuit P for moving the variable impedance element window.
and 11 smooth the mu LC signal. These are a capacitor and a resistor for determining the attack and recovery time constants of the LC. (June is the ground terminal. Below, we will explain the connection and electrical operation of the enclosure element. We will mainly explain the operation of only the channel. The other channel operates in the same way. 11 is the LC operation. Sometimes the impedance element 1 *b
Together with the transistor 61aQB, it is a resistor for exposing the input signal, and the transistor Q@mQB has its collector and power supply ivy connected in reverse to reduce distortion of the input signal during LC operation. - R% is a resistor for applying a base bias to the transistor QsGQ, and is set to a high resistance value (50 KaliiK) to reduce attenuation together with the resistor 11. Transistor Qs*04 is complementary! !
The collector of the transistor Q3 is grounded, the base is connected to the input terminal (1) via the resistor ml, and is biased from the 1ζ resistor 11, and the input signal is applied. Sanru. Its emitter is connected to the emitter bud of transistor Q4. transistor Q
The base of 4 is fed back the Ii current through the feedback resistor Ill, and is connected to the AC feedback legal terminal (2).
rL and the collector ζm of the output DC bias setting transistor Q-. M is a return resistance, and AC return resistance 111F≧
Both determine the AC voltage gain of the low frequency amplifier circuit.
ct) The potential drop caused by the sinking current of transistor q causes silver adhesion to the base of transistor Q4. Transistor Qso exclusively connected to 14 odes, emitter E 1m m ls connected to Ilk transistor. Q
i constitutes a current mirror am, and the mirror ratio is a resistance of 1.
Depends on the decision. Determined by resistor R1 nF:Q
, collector @@41. ) The collector of the transistor QI serves as an active load of the complementary differential amplifier circuit, and the collector of the transistor QI serves as an active load of the complementary differential amplifier circuit. Transistor % # Qf * 9 ports, Q, diode D1, resistor Is e l - low frequency amplifier circuit A
The main current potential of the output terminal (2) of the voltage 1 [[voltage Vcc
Regardless of the potential at the midpoint, that is, 1/tomagccD
A current is configured to set the current to position t. The base of the transistor Q is connected to the above *m- after removing the ripple component with a resistive capacitor C8 to prevent the lIc voltage pull component from being mixed into the above *m-. The base bias is exclusively applied through the resistor R1, &. A diode D1 and a resistor R4 are connected in series to the collector of the transistor Qy, and determine the current flowing through the transistor Qy. The base of the transistor Q@#QF is connected to the emitter of the transistor Qa, and the emitter of the transistor Q is connected to the ground 8n through a resistor RjllI having the same value. The collector of the transistor Q is connected to the base of the transistor Q4, and the collector is connected to the layered resistor 111. -7j,) The collector of transistor Q7 is transistor Q.
It is connected to the base of the resistance blade 4 and to one end of the resistance blade 4. Now, in the above mh, the voltage v1 between the base and emitter of each transistor is constant, and 6) II of the transistor
Assuming that the Ick-transportation number β5 is very large and ignoring the six bases @Tt, the current flowing through the resistor 14 is from the power supply voltage Vcc to the visa of the transistor Q9 and the diode P.
The forward voltage of ls (Vmic if Ds is a diode-P connected transistor) and the transistor Q-
The voltage obtained by subtracting the voltage of 9 and the voltage of 1 is combined by the resistance blade 4. Here, the voltage generated across resistor R1 is Vgg
Assuming that it can be ignored compared to (Majitomi), (Ma
g-4)/l is the bias current flowing into the resistance blade. From this bias current, the DC potential M at the output terminal (5) is expressed by the following equation. V@-((Vgg-47111)/it, )X
111 + 1VB To where * J”!” is set to be 11. 1 Y@I-Vcg-! VIm+2Vll*TVcg, and the output DC potential - becomes the midpoint voltage of the power supply voltage regardless of the power supply voltage Vgc. Next, a voltage is applied to the emitter of the transistor Q$.
X- determines the collector style. Resistance wing-1I
The voltage of Ii gear is approximately 1v regardless of the power supply voltage.
Since the collector current is constant, and the resistive current of the transistor Qsa is reduced, the current supplied to the complementary-differential amplifier circuit consisting of the transistors Q4a and QB is also constant. The pace voltage generated by the pace electrophoresis of the transistor Q and the resistor RB also remains constant regardless of the IT power supply voltage. The input signal applied to the m child (1) is amplified by the transistor QB*94 in a complementary differential amplifier circuit with the transistor Ct= as a load.
Sn is applied to the base of transistor Qll. The collector of transistor Qll is connected to the WIjt source terminal (2), and the emitter serves as its current source. Constant current source transistor Q. It is connected to the collector of n. The signal is transistor QS
f'L, ) is applied to the base of transistor Qll. Transistor Q1m s diode DI + resistor R·, 1g constitute an inverting field width amplifier. Its emitter current is determined by the resistor blades connected to the collector of the transistor Qll, and the resistor -0l.
The gain is determined by the mouth. The output signal is applied to the base of transistor Q14 f'L
, ) transistor Q11. It is output to its collector with the diodes Q1 and Ql- as loads. transistor Q
,, l) The base constitutes a calecitomirror shrine together with the transistor QIO, and the diode Q1 . . Qts, ) transistor Q8. is biased. The collector of transistor 'kW is transistor Q14
becomes an active load. The collector of transistor Q14 is
A PNP type transistor Qss and a shoulder PM type transistor QIO are connected to the base of a 10,000 transistor @Nishiki of a combination π composite transistor as shown in the figure. The collectors of transistors Q, t are connected to the base of transistor Qll, and each is amplified by transistor Q14 nT.
Two-signal power mark j1ml$R,) Emitter of transistor 41111, tactile ivy of transistor o1m and transistor Q! The connection point with the collector of o, that is, the output terminal (output to 5J, and take out as an AC output signal to load resistor IL)
nru. CSO is a phase compensation capacitor. The output signal is connected to the base of the transistor Qss of the differential amplifier -46a-11 constituting the comparator circuit C of the LC circuit so as to be input to the base of the transistor Qss. Transistor @a
Each electrical power supply of s e Qts has its cathode IjjJTt common through its diodes D, , D4@. 8n terminal connected to the collector of transistor Q, which is a current source. Transistor Qas # (lsi * a anti”
1@# l@1 constitutes a current mirror ial path, and transistors Q,. Diode connection from the collector of #
The output voltage is supplied to the output transistor Q1m. The base of the transistor Qu is connected to the emitter of the reference voltage output transistor Qs1 of the Jk quasi-ratio source B at 8rL. The collector of the transistor (ls@) is connected to the power supply terminal (8). The collector of the transistor Qu is connected to the power supply terminal (8) via the load resistor In. The base voltage of the differential amplifier QBHe QM is set to v
1 e VM and the erector current of the constant current transistor Qss is 10, the collector turtle 51fg of the transistor Qu is I'``''''' (1+ * x p * (vl
−%) ) “−”” (υ.l On the other hand, now there is no diode D4 @ ps in the differential amplifier construction,
Suppose that they are each directly connected to the collector of the transistor Qas by a common connection kIIt'L.弘＠-1・／ （14＠ztf(yl-ys)）
,,°°0°゛(2), above (1), -(V
A comparison of s-VM) vs. It is shown in Figure S. 1ilaic&, (a) shows the characteristics of the platform where the diodes Ds, D, are inserted in II6, and -) shows the characteristics of the platform with no single diode. This is because the change in I @ 0 with respect to lsi (g, tVt-v, ) it, that is, the improvement of the flip-flop vibration of transistor Q, is not gradual due to the insertion of the diode FDs-DH. The reference voltage l1Il is basically the transistor Chs +
Qss a Qu a Qu *Resistance”11 e 13
It is composed of 4 parts. The base of the transistor @110 is connected to a base bias via a resistor 1 to remove the ripple component with a resistor 11 m s and a capacitor vC to prevent the ripple component from entering the output voltage level 1jlLh. There is. Assuming that the resistance is mu a lsa u 74 E/value and vmg (approximately 0.TV) is sufficiently small compared to the turtle voltage, the resistance J = e 114 g) II M
The point becomes approximately -Vcc regardless of the electric voltage. The base of the transistor aSS is the above resistor 1sm e l
The xa 4D connection points kml and niotsuta are connected to the collector of the constant current source transistor Q1, and supply the emitter 111 current of the transistor Qll. Therefore. The emitter potential of the transistor Qll becomes Vcc+V1kK almost regardless of the vmg pressure, which is taken out as the base wP voltage and applied to the base of the transistor Qsa. Transistor Q13+ QMI QMI Qy*~II
v (b4 m on # Resistor L, II store constitutes a constant current source, and its electric value is determined by resistor R16. The current that is reduced by the resistor blade 1s is transferred to the transistor. Qsa * Current mirror opening at Qu, from the collector of transistor Qu to the collector of transistor Q1- and the base of transistor Qn 1118 B
, ) The current determined by the voltage between the base of transistor QH and the resistor 11 is determined by the voltage between the base and the terminal of transistor QH.
a QHa QBI+ with current mirror 1xrL. The reason why wtmwr is defined in the vertical scale as described above is to minimize the dependence of the constant current value on the 11iE source $7 pressure. This is the transistor 9 that constitutes the comparator circuit C.
It stabilizes the wL supplied to H# QH and also reduces the fluctuation of n-1c, which is the standard for MLC operation due to driving of the voltage. Now, the base potential of the transistor Q is the transistor QH.
When the base potential becomes higher than the base potential of the transistor Q, the collector current of the transistor Q increases as shown in the second section of the stone, and the MULCIIIilII signal is taken out to the load stud. Then, when the pace voltage of the transistor Qva reaches the specified level 1ζ, set the value of the resistor 1 so that a bias is applied to the base and emitter of the transistor (b).
And the drive enclosure for driving the variable impedance element Dew! A current flows through the transistor Ql constituting the current, and is smoothed by the conductor tcs. Gives the base current of the transistor @. When the transistor Q- is turned on, it drives the bases of the transistors Qs*Qs forming the transposed impedance element wings. By changing the saturation resistance & the resistor 11, the input signal @ is exclusively divided into voltages. Note that the resistor Rso connected to the collector of the transistor Q4@ is connected to limit the control electrophoresis of the rotation #8D, and when an excessive input signal is applied (outside the ALCk1 operating range).
It is effective for 1! ! 1m connected to improve the excessive sound of source throwing
The base of the transistor that takes kF is connected to the terminal (11) and the collector is connected to the Kameichi terminal (3) through the resistor!1. It is connected to the collector and base of the diode-connected transistor QsI through the transistor QsI.
connected to the base of. Transistor Q@HaQ-
・Work 1 → is grounded 8. The collector of the transistor Q1g is connected to the power supply terminal (2) via the resistor R14, and the transistors Qsy, Ql@Q
connected to the base. Transistor Qllr e
The emitter of QCs is grounded, and the transistor Qsy
The collector of is connected to the transistor Q・1+ via the resistor 111 &
Connected to the base of Q11. Transistor Qal
Tips for "Ta 1. - Connection 14. Armpit 1': h 5
> , ivy 01,0 construction ■ ivy. It is connected to the power supply terminal (3) via the resistor set 0. The collector of transistor 9.1 is connected to the base of transistor Q.l., the emitter of transistor ease is connected to terminal ICFC, and its collector is connected to terminal ICFC through resistor R8.
The terminals are connected to the power source terminals (2), respectively. The collector of transistor Q-1 is a transistor. Connect only to the base of transistor h, and ground the emitter of transistor Q. Also, the collector is the output transistor Q! -on the base of
They are connected to each other. Now, the power is only turned on without this transient reduction circuit ν.
Considering the lifting platform, terminal Q) is normal via 2 z vm
The time constant of the negative feedback resistor R11 and the capacitor c2 is required to increase the value, and as shown in Figure 118 (a), the output bias remains close to the source voltage for several seconds, and the normal output bias g
No. However, as shown in Figure 6 (b), the platform to which this circuit F was connected was turned on at about 8 pm when the power was turned on.
mml (QJ I QIs diode forward voltage)
IL transistor QJe supplies base current to transistor Q7 between terminals (2,) and negative layer # & anti-W1.
Regardless of 1u, it becomes 2v wisteria with 2 terminal voltage. Charge the transistor Q@! IQ・8 is connected to the output transistor Ql to prevent abnormal output from occurring during that time.
It absorbs the base wL current of 11 and makes the output bias almost at ground level. ) is the transistor g@4. When the voltage becomes qmg& conductive, the transistor Q- becomes conductive and no current is supplied to the base of the transistor Qs7. Charging on the terminal side J, the base short-circuit operation of the output transistor Q1- is canceled a1''L, and the operation becomes a positive amplification operation.In addition, this charging time is determined by the capacitor C connected to the terminal (4).
. By @msnru. In a configuration such as Samurai 1 or above, when an input signal is applied to the input terminal (υ), the low frequency amplification circuit ﾆ will amplify the signal by a gain of n determined by INF. Output terminal (June ζ output 8f'L). Since this DC voltage is the midpoint voltage of the voltage Vcc, the output signal is
The base input signal of the ξζ transistor Q36 becomes an alternating current signal that swings around Wa@.The current and voltage of the base input signal of the ξζ transistor Q36 are always approximately (j V c + Vl m ). The base input signal of transistor Q is approximately (L), which is the base potential of transistor Qss, as shown in FIG.
When the input signal level is lower than the input signal level, that is, when the input signal level is low or high, there is no current in the collector of the transistor QsI, so the transistor QsI is not driven through the load resistor -1, so the drive circuit p does not work. Therefore, the variable impedance element E is in a cut-off state, and the collector emitter impedance of the transistor Q1 e Ql becomes extremely large. The signal SO which has been amplified by the gain of the Kushiro module is taken out to the load resistor 1L 8t'L. Next, if there is a part where the input signal level becomes large (as shown in Figure 8), the base input signal of the transistor Q1m is also high, the excessive t corresponds to the electrophoresis I@ of the transistor Q
@nru to s. This current causes a voltage drop in the resistor R1ζ, which makes the transistor Qll#Q- conductive, lowering the saturation resistance of the collector-emitter of the transistor Ql*Ql, which is a variable impedance element, and increasing the input voltage.
By dividing the voltage between the resistor blade 1 and the resistor blade 1, the signal level output to the 41-pin (-) is lowered and muLC excitation is started. In the operation of the above example, by limiting the drive current of the drive circuit that moves the variable impedance element 'i', abnormal operation at the time of an excessive input signal during MLC operation is prevented, and normal ALC is maintained. Appendix Appendices The sound width device turns red in operation. In other words, if the variable impedance element IE is driven beyond the minimum saturation resistance and the variable impedance element IE is exceeded IIKML, the LC output signal may be distorted or otherwise malfunction due to the kidney effects of the variable impedance element, etc. −ζ becomes. Therefore, in the present invention, the transistor of the iam circuit *Q
4oh Q4* ノ"' Connect the thin limiting resistor to the lid and the power supply terminal (8), and connect the transistor before the variable impedance system element 5 becomes the minimum saturation resistance. Q4・a 64B drive current f111
11i, to improve the parasitic effects caused by the variable impedance element E, prevent distortion of the output signal at the time of excessive input when operating the ALCh, and create a normal LC appendix.
A: Currently, the operation of only one channel has been explained in 1 or more, but in Figure @1, the same operation is performed on other channels as well. The reference @jlEMs is shared by both channels, and in the embodiment, it is a transistor for the left channel comparison circuit and the right channel comparison circuit. The collector of m5hea is connected to a load resistor of 1N m111,
Transistor for left channel. a9゜Q4・and 1
11 tic *The right channel platform is configured tIrL to drive the variable impedance element TIr of each channel through a drive IN circuit consisting of a transistor Qu # 941 and a resistor 11f 1111. As described above, by sharing the reference voltage source 1, the level at which the mu LG starts to be applied and the ^L15 at the ALC thigh
The variation in the direction of the left and right leg channels of 1 bml is reduced. In particular, if it is integrated on the same chip, the 6E
It is hoped that the dispersion between both channels will be reduced. The above explanation has been given as a reference to the LC appendix, but as shown in Figure 114, a switch S is installed on the terminal, and the recording
It can also be used as a playback switch. That is, when the switch $ is open, it can be used as a recording amplifier as described above, and when the switch l is attached, it can be used as a stop amplifier. When switch 3 is closed, the transistor Qg*94! Because the base of is grounded 8tL. Since the operation of the drive 1mjlD is stopped and the variable impedance element is not driven, the transistor Ql
# The emitter-collector of Qz becomes a floating pattern, the input signal is no longer voltage-divided, and the output signal is amplified by the gain to the low-frequency amplification circuit and sent to the terminal (&J, (
7) is output. When the Mt switch S is open, the ALC operation is possible as described in section 1. As is clear from the above embodiments, the recording amplification circuit 6J of the present invention, a low frequency amplification circuit having a variable impedance element directly connected to direct current, and a standard with which the output voltage of this low frequency amplification circuit can be compared. with voltage source. A comparator circuit that compares the reference voltage of this reference voltage source with the output voltage of the mud low frequency amplification circuit, and a comparator circuit that receives the output signal of this comparator circuit and drives the variable impedance element to drive the low frequency amplification circuit. In a recording back amplifier circuit equipped with a drive path for controlling the output level. This is designed to limit the drive current of the drive circuit described above, and is effective in preventing abnormal operation at the time of an excessive input signal during ALC operation.Moreover, in order to limit the drive current of the variable impedance system element, This has the advantage of suppressing variations in power supply voltage, LC@threshold, etc.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram showing one embodiment of the present invention, am
The figure is a characteristic diagram of the comparison circuit used in the same example. Figure 1 is II! l! FIG. 4 is an explanatory diagram of the operation of the main part of the embodiment, and FIG. 4 is a wiring diagram of the main part W1 showing another embodiment of the present invention.
I is a transient characteristic diagram when the power is turned on. In the figure, M is a low frequency amplifier circuit, S is a reference voltage source, and C
is a comparison path, D is a drive circuit, mouse is a hair impedance element, and ν is a transient t@reduction path. Agent Ge Shuxin - Figure 2 Figure 3 Figure 4 Figure 1 Figure 5 Mt- Display of the case Japanese Patent Application No. 67-41071, Title of the invention Recording increase@it1m Person making the amendment 5, Invention of the specification subject to the amendment Detailed explanation column 6, "R8" on page 8, line 11 of the statement of contents of the amendment is replaced with "R4"
I am corrected. that's all

Claims (1)

[Claims] A low-frequency amplification circuit with N variable impedance elements directly connected to each other, a reference voltage source that can be softened in comparison with the output voltage of the low-frequency amplification circuit, and an i of this reference voltage line. a comparator circuit for comparing the quasi-voltage with the output voltage of the low frequency amplification circuit; and a comparator circuit that receives the output signal of the comparator circuit to drive the flexible Ishib dance element Jk. A Flit road with additional wheels, characterized in that it is equipped with a drive circuit for controlling the output level of the low frequency amplification circuit, and limits the drive current to the upper drive circuit in the width circuit.