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Патент USA US3058079

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Oct. 9, 1962
suA FoR' SUN
3,058,069
MULTIVIBRATOR WITH D.C. VOLTAGE FREQUENCY CONTROL
Filed July so, 1959
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INVENTOR.
SLJA FOR SUN
ATTORNEYS
United States Patent nice
1
3,058,669
2
D.C. control voltage and a diagram illustrating the re
1
lationship between these variables when compensation is
not provided.
MULTIVIBRATOR WITH D.C. VOLTAGE
,
FREQUENCY CONTROL
'
FIG. 1 represents a multivibrator with two transistors
Sua For Sun, Zurich, Switzerland, assignor to Landis &
Gyr, A.G., Zug, Switzerland, :1 body corporate of
T1 and T2, the collector of transistor T1 being coupled
Switzerland
‘ ’
'
3,058,069
Patented Oct. 9, 1962
via a resistance R1 to the base of transistor T2, and the
collector of transistor T2, (junction a) being connected
Filed July 30, 1959, Ser. No. 830,658
Claims priority, application Switzerland Aug. 20, 1958
4 Claims. (Cl. 331--113)
This invention relates to that class of electrical pulse
via a coupling condenser C1 to the base of transistor
T1. The emitters of the two transistors are grounded,
10 while the base of transistor T1 (junction b) is controlled,
via a parallel circuit R2, C2, by a variable D.C. potential
Us. This, then, is a multivibrator with transistors in
common-emitter connection. The circuitry is completed
potential.
resistances R3 and R4 in the collector circuits of tran
Multivibrators are used to generate signals with special 15 by
sistors
T1 and T2 respectively. A source of potential
voltage curves, for example sawtooth, trapezoidal or
Ub is connected between grounded terminal e and a ter
rectangular. Such multivibrators have two ampli?er
minal c, the latter being connected to resistances R3 and
components for example electron tubes, transistors, and
R4. Terminal 0 is negative relative to terminal e. The
the like, the output of each ampli?er component being
output of the multivibrator is taken from terminal d
coupled by way of an RC combination back to the input
at the junction of R1 and the collector of T1.
of the other ampli?er component. The frequency‘ of
Upon suitable choice of resistances R1 to R4, there is
oscillation of these multivibrators is determined by the
a negative impedance between junctions a and b, which,
time constant of the RC coupling, but the frequency may
owing to interposition of the coupling condenser C1, pro
also be varied by means of a D.C. potential applied at a
duces oscillations appearing in the form of rectangular
particular point in the multivibrator circuit. Multivi 25 pulses
of like polarity between the output terminals 0
brators of this latter type have the disadvantage that
and
d,
or
d and e. The ‘frequency of the pulse sequence
the frequency of oscillation does not vary linearly with
is
approximately
inversely proportional to the capacitance
the applied D.C. potential.
of the coupling condenser C1.
This aberration is particularly troublesome when such
known multivibrators, the frequency of oscillation
D.C.-controlled multivibrators are used, for example, in 30 as In
a function of the applied D.C. control voltage shows a
a remote indication system in which data represented
non-linear behavior which has been represented in FIG.
by a D.C. potential are to be converted into propor
2 by the solid curve K1. Now it has been found that
tional pulse repetition rates.
by connecting a condenser C2 or a capacitive network of
There is a known multivibrator in which there is,
suitable capacitance in parallel with the resistance R2,
within a certain interval, a linear relationship between a 35 the frequency vs. D.C.-control-voltage characteristic is
D.C. potential and the frequency of oscillation produced
linearized within the voltage interval B, as indicated by
thereby. This multivibrator, however, requires at least
the dotted curve K2 in FIG. 2. This linearization is
one magnetic core of high-permeability sheet-metal and
circuits known as multivibrators and more particularly
to multivibrators which are controlled by a variable D.C.
doubtless due to the fact that the time constant of the
a plurality of windings, so that its manufacture is com
paratively costly.
40
‘In contrast, the invention of this application provides
discharge circuit of coupling condenser C1 increases
slightly with condenser C2 connected, and this in such
non-linear relation to the D.C. control voltage Us, as to
a multivibrator with D.C. voltage control wherein the
above-mentioned disadvantages are avoided by provid
ing, in series in the input circuit of the multivibrator, a
compensate for the non-linearity originally present.
The operating range of the multivibrator with regard
to D.C. control voltage and frequency is adjustable With
network comprising the parallel combination of resistance 45 in comparatively wide limits by suitable choice of cou
and capacitance.
pling resistance R1, resistance R2, and coupling condenser
C1. If the coupling resistance R1 is increased, the fre
It is accordingly an object of the invention to provide
a D.C. voltage-controlled multivibrator which has a
quency of oscillation of the multivibrator, for constant
linear relationship between the variable D.C. voltage
D.C. control voltage Us, becomes higher. An increase
input and the pulse repitition rate output; in other words, 50 in the value of resistance ‘R2 on the other hand, results
a multivibrator of this type with a linear transfer func
tion.
It is a further object to provide such a controlled
multivibrator in which a wide range of linearity is
achieved, not with complicated compensating circuits,
in a decrease in frequency of oscillation.
As ampli?er components, use may be made of tran
sistors, controlled electron tubes, etc. In the use of
55
transistors, a temperature compensation arrangement
must be added.
This purpose may be served, for exam
but rather with a simple passive network of elementary
ple, by replacing coupling resistance R1 and/or resistance
electrical components.
R2 by a circuit with temperature-sensitive components.
These and other objects of the invention will be set
Such compensating circuits are known, and therefore
forth in part hereinafter and in part will be obvious here
require no further elucidation here.
60
from, or may be learned by practice with the invention,
As ‘an example of the use of the invention, remote
the same being realized and attained by means of the
instrumentalities and combinations pointed out in the
appended claims.
metering of electric power may be mentioned. The
electric power consumed at a station is converted into a
D.C. potential by means of which the described multi
The invention consists of the novel parts, constructions,
arrangements, combinations and improvements herein 65 vibrator is controlled. The pulses generated at the out
put of the multivibrator are supplied, for example, via the
shown and described.
electrical distribution network, to a pulse counter located
The drawing shows an exemplary embodiment of the
at the point of indication. Since the pulse frequency
invention of which:
bears a linear relation to the D.C. control potential of
70 the multivibrator and hence also to the electric power to
FIG. 2 shows a diagram of the repetition rate of the
be measured, the number of transmitted pulses observed
FIG. 1 multivibrator plotted as a function of the applied
per unit time is a measure of the electric power. An
FIG. 1 shows the circuit of a multivibrator with D.C.
voltage control;
3,058,069
3
4
ported by the liquid and acting on a potentiometer con
trol, and the potential in turn controls the multivibrator.
At the point of indication, the pulse frequency is meas
ing control circuit connected to one of said ampli?er
inputs and adapted to be energized by a variable ampli
tude DC. voltage comprising a resistance-capacitance
combination connected in series with said one input.
2. Apparatus according to claim 1 in which said con
trol circuit is connected to the input of said ?rst ampli
ured, ‘being a measure of the liquid level.
The invention in its broader aspects is not limited to
3. Apparatus according to claim 1 in which said ?rst
other practical example occurs in a remote indication
system for the liquid level in a tank. Here the level is
converted into a DC. potential by means of a ?oat sup
?er.
and second ampli?ers comprise transistors having base
the speci?c mechanisms shown and described but de
partures may be made therefrom within the scope of the 10 inputs and collector outputs.
4. Apparatus according to claim 1, in which said
accompanying claims without departing from the prin
ampli?ers
comprise transistors and in which said re
ciples of the invention and without sacri?cing its chief
sistance-capacitance combination includes a resistor and
advantages.
' capacitor connected in parallel.
What is claimed is:
1. A D.C. voltage controlled multivibrator having a 15
References Cited in the ?le of this patent
linear relationship between input control voltage and
output frequency comprising ?rst and second ampli?ers,
UNITED STATES PATENTS
resistance means coupling the output of said ?rst ampli
2,331,317
?er to the input of said second ampli?er, capacitance
means coupling the output of said second ampli?er to 20 2,598,516
the input of said ?rst ampli?er, and a passive lineariz
Germeshausen ________ .. Oct. 12, 1943
Dickinson ___________ __ May 27, 1952
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