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Патент USA US3082362

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March 19, 1963'
Filed Jan. 4, 1961
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United States Patent
The two grids of the gas-?lled triodes '4 and 5 are
connected by protective resistors 21 and 22 to the nega
Rudolf Diener, Zurich, Switzerland, assignor to
Elemag-Anstalt, Vaduz, Liechtenstein
Filed Jan. 4, 1961, Ser. No. 80,626
Patented Mar. 19, 1963
4 Claims. (Cl. '315-163)
tive pole of a DC. voltage source 23, the positive pole
of which is connected to the junction point 24 of the
cold cathode diode 11 and the resistors 9, 10, 12, 14.
The junction point of the cold cathode diode 11 and the
resistors 10 and 17, the ‘condenser 15, and the cathode of
the gas-?lled triode 13 is denoted by reference 25, while
the. junction point of the potentiometer 19, the voltage
Tocontrol the striking phase of gas-?lled triodes, use 10 source 20 with the resistors 17 and 14, the condenser
is generally made of ‘a phase-shift bridge and a pulse‘
15 and the recti?er 16 is denoted by reference 26. The
transformer which feeds a striking pulse to the grid of
anode of vthe gas~?lled triode113 is connected at the point
the gas-?lled triode when a certain phase shift is reached.
27 to the resistor 12, recti?er 16 and the cathodes of the
The disadvantage of these circuits is that the striking
gas~?lled triodes 4 and 5.
phase can be controlled only within a range of about 15
A third secondary winding 28 of the transformer 1 de
150°‘ if circuit cost is to be kept fairly low. Even with
livers the heater current vfor the cathodes of the gas-?lled
this limitation of the range of control, however, circuits .
triodes 4, 5 and 13, as indicated by the terminal refer
of this kind are relatively expensive, particularly ow
ences ff in the usual way.
ing to the pulse transformer, and inaddition they con
The circuit described ‘operates as follows: if no voltage
sume a considerable power. Theobject of ‘the inven 20 drop occurs at the resistor 12 to counteract the negative
tion is to obviate these disadvantages by a relatively sim
bias of the grids of the gas-?lled triodes 4 and 5 as sup~
ple, inexpensive circuit.
plied by the voltage source 23, then these gas-?lled triodes
The circuit according to the invention comprises one
are cut off and the load 6 receives no current whatever.
or more main gas-?lled triodes Whose striking phase is
A current can ?ow through the resistor 12 in the circuit
to be controlled and normally held non-conductive by 25 24, 12, .1‘3, 25 if the auxiliarygas-?lled triode 13 is con
negative grid bias thereon. ‘The ‘circuit also includes‘
ductive; the period of time during which this is the case
an auxiliary gas-?lled triode, the grid circuit of which” ‘depends, as will be explained in detail hereinafter, on the
has means for setting a negative grid bias voltage thereon;
setting of the tap of the potentiometer 19, so that the
a condenser charged through a resistorby trapezoidal
striking phase of the gas-?lled triodes 4 and 5 and hence
voltage half-Waves derived ?rom an alternating voltage 30 the current drawn vby the load can ultimately be controlled
through a recti?er untilthe condenser voltage balances‘
by the adjustment of said tap.
out the negative grid bias voltage on the auxiliary gas
The voltage occurring at the output of the recti?er
?lled trade and this triode strikes; and a second resistor
bridge 7 during a full A.C. cycle T has the form of two
which is common to the anode circuit of the auxiliary
recti?ed sinusoidal half-waves, which are regarded as
gas-?lled triode and to the grid circuit of each main‘ gas 35 positive. In the absence of the cold~cathode diode 11,
?lled triode, so that on the striking of the, auxiliary gas
two positive sinusoidal half-waves e1 shown in broken
?lled triode a voltage drop across the second resistor bal
‘ lines in FIGURE 2 would also occur at the resistor 10
ances out negative bias on the grid of each other main
of the voltage divider 9, 10, that is to say between the
gas-?lled triode causing it to strike when its- anode is
points 24 and 25; Since the cold-cathode diode 11 con~
positive with respect to its cathode.
ducts when its striking voltage Ez is reached, it limits
An embodiment of the invention will be described by
the voltage 22 between the points 24 and 25 to the
way of example with the aid of the accompanying draw
somewhat lower normal-running voltage EB, so that this
ings wherein:
voltage e2, which is shown in solid lines in FIGURE 2,
FIGURE 1 shows an example of circuit according to
has substantially the shape of low trapezoids. The con
the invention; and
FIGURE 2 is an explanatory diagram.
The primary Winding 2 of ‘a transformer 1 is connected
to the A.C.>mains. Two gas-?lled thyratron triodes 4
denser 15, which is fully discharged at the beginning of
each half-wave, charges up through the resistor 14, the
time constant RC of the charging circuit 14, 15 being
relatively high, so that the voltage at the condenser or
at‘ the resistor 17 parallel therewith rises relatively slowly,
3 of this transformer in a full-wave recti?cation circuit. 50 oris still substantially linear Within a half-cycle and if
The striking phase of these gas-?lled triodes 4 and 5 is
the voltage 122 were maintained, the voltage e3 would
and 5 and a load 6 are connected to a secondary winding
to be controlled so as to vary the current drawn by the
load 6. A recti?er bridge 7 is connected to another sec—
‘asymptotically only approach voltage e2 some time later.
In the grid circuit of the auxiliary gas-?lled triode 13, the
ondary winding 8 of the transformer 1. The output volt
voltage occurring at the condenser 15 and at the resistor
age of the bridge 7, which consists of recti?ed sinusoidal 55 17 parallel thereto is directed in opposition to the voltage
half-waves, is fed to two resistors 9and 10 which are
tapped 011 from the potentiometer 19. In FIGURE 2,
connected in series and form‘ a voltage divider. A cold
the positive value of the voltage tapped olf from the
cathode diode 11 serving as avvoltage limiter is con
potentiometer 19 is denoted by the reference e4. As
nected in parallel with the resistor 10. The series cir
long, as e4 is larger than e3 the grid of the auxiliary
cuit comprising a resistor 12 and an auxiliary gas-?lled 60 gas-?lled triode 13 has negative bias and thus this aux
triode 13, and the series circuit comprising a resistor 14
iliary gas-?lled triode .13 is cut oil; When e3 becomes
and a condenser 15 are in turn connectedin parallel with"
equal .(or substantially equal) to e4, as occurs in the ?rst
the cold-cathode diode 11. The terminals of the resistors
half-cycle at the point‘ P1 at the time T2, the auxiliary
12 and 14 remote from the cold-cathode diode 11 are
gas-?lled triode 13 strikes vand conducts .and the‘con
connected together by a recti?er 16, while a resistor 17
denser 15 discharges through the recti?er 16 and the
is connected in parallel with the condenser 15.
auxiliary gas-?lled triode 13. Once the auxiliary gas~
The grid of the gas-?lled triode 13 is connected by a
?lled triode 13 has struck, it continues to conduct, so
protective resistor 18 to the movable tap of a potentiom
eter 19 fed by a DC. voltage source 20. The positive
pole of the voltage source 20‘ is connected by the resistor
17 to the cathode of the auxiliary gas-?lled triode 13.
that as from the moment T2 a current ?ows, as a result
of the voltage 22, from the point 24 through the resistor
12 and the auxiliary gas-?lled triode 13 to the point 25.
In the grid circuit of the gas-?lled triodes 4 and 5, the
voltage drop at the resistor 12 is directed in opposition
to the negative bias supplied by the source 23 and iS
equal (or substantially equal) in magnitude to this bias,
so that the gas~?lled triode whose anode is positive with
respect to the cathode, for example the gas-?lled triode
4, strikes and continues to conduct from the striking time
T2 until the time
also consume a much lower power during operation. The
potentiometer 19 may be calibrated in degrees correspond
ing to the striking commencement phase or, for example,
in percentages of the maximum current that can be fed to
the load 6.
What we claim is:
1. A circuit for controlling the striking of a main
gas-?lled triode having an anode and cathode connected
to an alternating sinusoidal voltage in circuit with a load,
10 said triode having a grid circuit normally biased negative
atwhich the ?rst half-cycle ends. At the end of the
ly to cut-01f the triode, comprising a gas-?lled control
?rst half-cycle the gas-?lled triodes 3 and 4 are ex
triode having another anode, cathode and grid circuit,
tinguished, because the relevant anode voltages become
means for applying an adjustable negative bias to the grid
of the control triode to cut-off the» control triode, a direct
The process described is repeated in the second half 15 current source and a ?rst resistor connected in series with
cycle, striking of the gas-?lled triode 3 occurring at
the anode and cathode of the control triode and also con
the point P2 at the time
nected to the grid circuit of the main triode to apply
the ?rst named negative grid bias thereto, a condenser
T ,
and a second resistor connected in another series circuit
5+ T2
20 so that said other series circuit has a predetermined time
This time the gas-?lled triode 5 strikes and continues to
constant, means for applying a charging, cyclical direct,
conduct until the time T.
amplitude limited voltage to said condenser through said
If the cold-cathode diode 11 acting as a voltage limiter
second resistor, means for deriving said direct voltage
were not provided, the condenser 15 would not be charged
vfrom said alternating sinusoidal voltage, means for limit"
up by a constant voltage during substantially one half 25 ing the charging voltage to a predetermined magnitude so
cycle. The condenser voltage would not rise substantial
that the charging voltage has -a trapezoidal wave shape
ly linearly but would rise initially with ya much steeper
in each half cycle thereof, said other series circuit being
slope, while between
connected to the grid biasing means of the control triode
so that the negative bias 'on the grid of the control bias
30 is overcome by the voltage of the charging condenser
to strike the control triode and pass a current through its
anode and cathode and through the ?rst resistor, whereby
passage of current through the'?rst resistor upon striking
of the control triode overcomes the negative bias on
it would rise only very slowly, so that the lines c3 and 35 the grid of the main triode and the main triode strikes
e4 would not furnish any sharp points of intersection
or any points of intersection P1, P2 at all near
to pass a current to the load when the anode of the main
triode is positive with respect to the cathode of the main
2. A circuit according to claim 1, wherein the limit
40 ing means for the charging voltage includes a diode hav
or T.
ing a cold cathode, said means for deriving the direct
With the present circuit the striking phase can be con
voltage fromlthe alternating sinusoidal voltage including
trolled practically within a range of 180°. It may even
a full wave recti?er bridge, said recti?er bridge having
be controlled beyond 180". In fact, if the potentiometer
an input and output, said input being connected to the
voltage e4 is so selected thate3 and e4 do not intersect
alternating voltage, and voltage divider resistors connect-y
in the first half-cycle, then'the condenser 15 does not
ed across the output of the recti?er bridge, said diode
discharge at the end of this half-cycle but continues to
being connected in parallel with one of the voltage di
charge up in the second half-cycle, as shown in broken
vider resistors.
lines. The resistor 17 has a very high resistance so that
3. A circuit according to claim 1, further comprising
the current through the resistor 17 in the short transition
period during which the voltage is smaller than BB, is 50 a recti?er connected between the anode of the control
negligible. The ?rst striking point P1 is then in the
second half~cycle, the next striking point in the fourth
half-cycle, and so on. In the present connection, namely
for the control of the current supplied to the load 6 by
recti?er vand the condenser, so that the condenser dis- ‘
charges through the control triode when the control
triode strikes.
4. A circuit according to claim 2, wherein the means
the gas-?lled triodes 4 and 5, striking at the point P1 in 55 for applying adjustable negative bias to the grid of the
control triode includes an adjustable potentiometer and
the second half-cycle, in which case only the gas-?lled
source of direct voltage, so that the striking of the main
triode 5 would operate, is pointless, but cases are'possi
triode can be controllably set to occur at any instant in
ble in which a phase shift of the striking time in a range
each 360° cycle ranging from more than 0° to less than
of more than 180° may be advantageous. In the present
case the potentiometer will be Provided with a stop to 60 360°.
prevent control beyond 180°.
The circuit described has the advantage of ensuring a
References Cited in the ?le of this patent
large range of control and a very exact control at very
small cost. The requisite tubes 11 and 13, and the
various resistors, the condenser 15 and the recti?er 16
are in ‘fact much cheaper than the transformers and
phase shift bridges used in conventional circuits and they
Cooper ______________ .._ June 10, 1947
Large _______________ __ Nov. 11, 1952
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