1. * GB780003 (A)
Description: GB780003 (A) ? 1957-07-31
Electronic switching unit
Description of GB780003 (A)
PS ', v = f: Of i
PATENT SPECIFICATION
Date of Application and filing Complete Specification July 9 1952
N. 37888156 Application made in Netheriands on July 12, 1951.
(Dividedout of No. 780,001).
Complete Specification Published July 31. 1957.
30,003 The inventor of this invention in the sense of being the actual
deviser thereof within the meaning of Section 16 of the Patents Act
1949, is Antonie Snijders of 28 Enschedelaan, The Hague, the
Netherlands, a subject of the Queen of the Netherlands.
ladex a: azce:ddnce -Class 40(6), G(1M: 2G: 3D: 3K: 3R).
ln:.. nationa! Csasiflction A-H03k.
COMPLETE SPECIFICATION
CORPECTIONOF CLEEICAL EPROR SPECIFICATION 10. 730,003
The following correction is in accordance with the Decision of the
Assistant Comptrollers acting for the Comptroller-General, dated the
twentyfifth day of February, 19583.
Page 1i lines 3 to 6; for "Octrooiafdeling C145; 4 St. Paulusstraat,
Leidschendam; Holland, formerly of Kortenaerkade i2 'The Hague,
Holland,, read "12, Kortenaer.tade, The Hague. The Netherlands, ".
THE PAT-/T OFFICE, goth June, lq58 negative terminal ania mer anoraes
via scparate, mutually equal anode resistors to the positive terminal
of a voltage source; a first lowohmic and a first high-ohmic voltage
divider both connected between the anode of the input tube and the
negative terminal of the voltage ZS source; a second low-ohmic and a
second highohmic voltage divider both connected between the anode of
said following tube and the negative terminal of the voltage source;
whilst the control grid of said following tube is controlled from a
tapping point of said first high-ohmic voltage divider.
The applied switching potential may be static or dynamic; the highest

2. working frequency is limited mainly by the parasitic capacitance in
the circuit and the resistance values therein.
The particular working of the switching unit, that is, producing at
its output terminals the nominal value of the applied switching
potential and the inverted value of the same whilst regenerating its
amplitude, makes this switching unit particularly suitable for
application in co-operation with diode circuits, while the switching
voltages to be applied at these Fric 3s. 6d.] DB Oele82/1(4)1/363e6
150 e/58 R reference potential of all the associated units is supplied
by the common conductors, which 65 are interconnected.
The simplicity in construction of the relevant switching unit is
obtained by use of uniform parts, especially resistors, as the
resistors which constitute the branches of the first and 70 second
low-ohmic voltage divider and the stabilizing-branch resistors for
providing the reference potential have mutually equal values, just as
the branch resistors of the first and second high-ohmic voltage
divider and the 75 resistor for providing the reference potential of
the later, which resistors for the remainder are high in ohmic value
with respect to the first mentioned resistor, whereas the resistor for
providing the reference potential of the first 80 high-ohmic
voltage-divider is approximately one fourth of the ohmic value of that
of the second high-ohmic voltage-divider.
By applying the switching unit according to the invention between
successive switching 85 stages, each provided with rectifiers the
amplitude of the switching potential can be kept small as it becomes
regenerated by the relevant t, PATENT SPECIFICATION
780,003 Date of Application and filing Complete Specification July 9
1952 / i No. 37888/56 Application made in Netherlands on July 12,
1951.
Y 2 (Dividedout of No. 780,001).
Complete Specification Published July 31. 1957.
The inventor of this invention in the sense of being the actual
deviser thereof within the meaning of Section 16 of the Patents Act
1949, is Antonie Snijders of 28 Enschedelaan, The Hague, the
Netherlands, a subject of the Queen of the Netherlands.
Index at acceprance -Class 40(6), G(IM: 2G: 3D: 3K: 3R).
Inte. national C(a:1siRcotion -HO3k.
COMPLETE SPECIFICATION
Electronic Switching Unit We, STAATSBEDRIJF DER POSTERIJEN, TELEGRAFIE
EN TELEFONIE, a Public Department of The Netherlands of
OCtrooiafdeling C 148, 4 St. Paulusstraat, Leidschendam, Holland,
formerly of Kortenaerkade 12, The Hague, Holland, do hereby declare
the invention, for which we pray that a patent may be granted to us
and the method by which is to be performed, to be particularly

3. described in and by the following statement:-
The invention concerns an electronic switching unit for use in
code-converters, e.g. as described in British Patent Application No.
17359/52 (Serial No. 780,001).
The electronic switching element according to the invention comprises
an input tube and a following tube having their cathodes connected via
a common cathode resistor to the negative terminal and their anodes
via separate, mutually equal anode resistors to the positive terminal
of a voltage source; a first lowohmic and a first high-ohmic voltage
divider both connected between the anode of the input tube and the
negative terminal of the voltage iS source; a second low-ohmic and a
second highohmic voltage divider both connected between the anode of
said following tube and the negative terminal of the voltage source;
whilst the control grid of said following tube is controlled from a
tapping point of said first high-ohmic voltage divider.
The applied switching potential may be static or dynamic; the highest
working frequency is limited mainly by the parasitic capacitance in
the circuit and the resistance values therein.
The particular working of the switching unit, that is, producing at
its output terminals the nominal value of the applied switching
potential and the inverted value of the same whilst regenerating its
amplitude, makes this switching unit particularly suitable for
application in co-operation with diode circuits, while the switching
voltages to be applied at these [Nce 3s. 6d.] circuits (e.g.,
coincidence circuits) effect rela- 4 5 tively low voltage amplitudes
at the outputs of the same, caused by the finite resistance values of
the diodes in blocking condition, and the somewhat considerable
resistance values of the diodes in conductive condition. Said
regenerative effect of the electronic switching unit according to the
invention is obtained without making use of auxiliary voltages but by
use of the above-mentioned voltage dividers, which for this purpose
are provided with extra 55 branches, which are connected to each other
via a common conductor. Thus a fixed potential is derived from the
circuit which can serve as a reference potential for various switching
units co-operating in any circuit. 60 By this means, only one voltage
source suffices, and if more electronic switching units according to
the invention are provided, the reference potential of all the
associated units is supplied by the common conductors, which 65 are
interconnected.
The simplicity in construction of the relevant switching unit is
obtained by use of uniform parts, especially resistors, as the
resistors which constitute the branches of the first and 70 second
low-ohmic voltage divider and the stabilizing-branch resistors for
providing the reference potential have mutually equal values, just as

4. the branch resistors of the first and second high-ohmic voltage
divider and the 75 resistor for providing the reference potential of
the later, which resistors for the remainder are high in ohmic value
with respect to the first mentioned resistor, whereas the resistor for
providing the reference potential of the first 80 high-ohmic
voltage-divider is approximately one fourth of the ohmic value of that
of the second high-ohmic voltage-divider.
By applying the switching unit according to the invention between
successive switching 85 stages, each provided with rectifiers the
amplitude of the switching potential can be kept small as it becomes
regenerated by the relevant 780,003 switching unit. For that reason
the voltage, that the rectifier-cells used must withstand, when in
blocking condition, can be small.
The switching unit according to the invenS tion can be employed in
circuits for the inversion of the two switching potential values,
which is a practice, necessary in binary computer systems.
The particular advantage when using the switching unit for this
purpose here again consists in the regeneration of the voltage values,
without needing special elements to this end.
Finally the switching unit according to the invention offers the
possibility of feed-back in a high-chmic loon between the tavning
point of the second high-ohmic voltage divider and the control-grid of
the input tube, as a result of which the circuit becomes less
sensitive to small fluctuations of signalling or supply voltages,
though it remains under full control of said signalling voltage.
The invention will be explained in detail with reference to the
accompanying drawings in which:AS Fig. 1 shows the circuit of the
electronic switching according to the invention, and the
block-schematic of the same; Fig. 2 shows the working characteristics;
Fig. 3 shows an exemplary coincidence-circuit provided with electronic
switching units according to the invention.
The circuit according to Fig. 1 comprises two tubes Bla and Bib (which
may be constructively unified as a double-triode in one envelope), of
which the first one (input tube) is primarily controlled at its
control grid via terminal 7. Dependent on this control, one of the
tubes is conductive, while the other one is non-conductive. The input
terminal 7 is connected with the control grid of tube Bla via a grid
resistor RiO, which limits the grid current.
The cathodes of both tubes are connected to the negative terminal 11
of a voltage source V via a common cathode resistor R15. The anode of
tube Bla is connected at the positive pole 2 of said source V via
parallel anode resistors Ri and R2, and the anode of tube Bib is
connected to positive pole 2 via R4 and R5.
Furthermore the anode of tube Bla is connected via a voltage divider

5. comprising resistors R6. Rll to the negative pole 11, the anode of
tube BIb being connected in the same way via the voltage divider
comprising resistors R9, R19. The branch resistors R6, R9, R11 and R19
have mutually equal resistance values, and as also the anode resistors
RI, R2, R4 and R5 have mutually equal resistance values the result is,
that the voltages, supplied at the tapping points 9 and 4 of the said
voltage dividers alternate when the conductive condition of the tubes
is changed.
The said voltage dividers are relatively lowohmic. Two further voltage
dividers are provided, both of relatively high-ohmic value. The anode
of tube Bla is connected via one of these further high-ohmic voltage
dividers R8, R16, the resistors of which have mutually equal values,
with the negative terminal ll. The anode of the following tube Bib is
in a simi- 7 lar manner connected to terminal il via highohmic voltage
divider R7, R14, the resistor values of which are also mutually equal,
and equal to those of R8, R16. The latter voltage divider (R8, R16)
has its tapping point con- 7 nected to the control grid of the
following tube BIb, and via resistor R17 to the common conductor which
is connected to terminal 6.
The high-ohmic voltage divider R7, R14 has its tapping point connected
to terminal 5, 8 which will be described hereinafter, and is connected
via resistor R13 to the said terminal 6.
The low-ohmic voltage dividers R6, Rll and R9, R19 are connected to
said terminal 6 via resistors R12 and R18 which are equal in value 8
to the resistors R6, RI 1, R9 and R19. The circuit is furthermore
provided with neon indicator tubes Li and L2, which are connected (in
series with common limiter resistor R3) to terminal 2 of voltage
source V and the anodes 9i of tubes Bla and Bib, respectively.
The operation of the circuit is as follows It is supposed that tube
Bla is conductive (the control grid of Bla is kept positive with
respect to its cathode). 0 Responsive thereto the output tube Bib will
be non-conductive and output terminal 4 will be positive with respect
to the output terminal 9, as the latter is connected to the anode of
tube Bla, which takes current via anode 1l resistors RI and R2. The
high-ohmic voltage divider now keeps the control grid of tube Bib
negative with respect to its cathode, so that this tube cannot become
conductive unless the condition of the first mentioned tube 1(
changes. As the resistors R12 and R18 have equal resistive values the
potential at terminal 6 will have a value, which is the means between
the potentials at terminals 4 and 9.
In Fig. 2 curves are shown, which represent 1! the voltage variation
at terminals 3 and 10 that is, at the anodes of tubes Bla and Bib.
At the left scale the absolute potential (that of terminal li being
taken as ground or zero potential) is mentioned at the right hand

6. scale 1E a relative scale is used, taking the reference potential of
terminal 6 (70 volt absolute) as zero level. The voltage source V has
a value of approx. 220 volt in this circuit; the resistance values of
this exemplary circuit are R, 1:
R2, R4, R5, R6, R9, Rll, R12, R18 and R19 each 39000 ohm R7, R8, R13,
R14 and R16 each 1,000,000 ohm; R3 about 820,000 ohm; RIO about
470,000 ohm; R15 about 15000 ohm and R17 about 270,000 ohm. Tubes Bla
L and Bib may be a double-triode E 90 CC; the neon tubes Li and L2 may
be of any type as used for indicator purposes in counter or flipflop
circuits.
In Fig. 2 at A the potential curve at the 1l 780,003 anode 10 of tube
Bla and that at the anode 3 of tube BRb are shown as a function of the
control grid voltage of tube Bla. Curve B represents the potentials at
terminals 4, 6 and 9 as a function of the said grid potential.
Hereinafter the absolute potential values (left hand scale) are
mentioned. If at terminal 7 the grid potential amounts to 60 V tube
Bib will be conductive and the potential at terminal 3 will amount to
approximately 105 V, whilst (as tube Bla is non-conductive) the
potential at terminal 10 amounts to approximately 172 V, so that the
potentials supplied at terminals 4 and 9 will be approximately 58 V
and 82 V respectively. As terminal 6 is influenced by these potentials
via two equal resistors the potential at terminal 6 will amount to
approximately 70 V. This latter potential in its turn influences the
grid potential of tube Bib via resistors R17.
When the grid potential increases to approximately 69 volt tube Bla
will become conductive; terminal 10 supplied approximately 170 V which
value decreases somewhat as the triggering limit is approached, tube
Bib will correspondingly decrease its conductivity. Then terminal 3
supplied approximately 106 V, which increases somewhat as the
triggering limit is approached terminals 4 and 9 supply 59 and 79 V
respectively; point 6 is at approximately 69 volts.
When said grid potential of tube Bib increases further the tube
conditions are fully changed, and for the value 82 volts the potential
at points 9, 6, 10 and 3 will amount to 58, 69, 106 and 172 volts
respectively.
From the curves it appears that the reference potential is kept
sufficiently constant over the whole range (with respect to the
voltage-source terminal potential). The regenerated switching
potentials, supplied at terminals 4 and 9 are also substantially
constant, and have values of practically 60 and 80 volts, which values
alternate as the grid voltage of tube Bla crosses the switching value;
this means in practice if said grid voltage differs less than
approximately 0,5 volt from said reference potential (70 volt).
The switching voltage values thus may vary between 60 volts and 70,5

7. volts, and between 80 volts and 69,5 volts practically without change
of the output potentials.
By increasing the grid voltage at the input terminal 7 triggering
occurs when the grid voltage surpasses the value 70,5 volts; by
decreasing the grid voltage on the contrary triggering occurs when the
value 69,5 volts is reached, as indicated in the dotted line part of
the curve.
The neon tubes L1 and L2 get potential of approximately 120 volt at
the terminal of the common resistor R3, so that that neon tube that is
connected with an anode that bears a voltage of less than 110 volt,
will glow.
The output terminal 5 supplies the same potential as output terminal
4, however, the former circuit is of higher ohmic value than the
latter circuit. For that reason this output can serve for stabilizing
purposes when connected through to input 7. The increased stability
caused by this measure keeps the circuit less sensitive to small
variations in the switching voltage amplitude or in the battery
voltage V. As the potential supplied by terminal 5 is taken from a
high-ohmic circuit, this potential will not be able to seriously
influence 75 the controlling voltage, applied (low-ohmic) at terminal
7, so that a slight but sufficient stabilizing effect is obtained.
If a plurality of electronic switching units F, F', F" and F"' is
provided, all operating at 80 between 60 and 80 V controlling
potentianal value, then all the stabilizing terminals, such as 6, 6',
6' and 6' are connected through, as shown in Fig. 1. As a result the
reference potentials at these points are stabilized and 85 equalized,
so that a real regeneration of the output voltages becomes possible.
All output potentials will bear equal nominal values in response
thereto. The voltage source V may be common to the various cooperating
switching units, such as F, F', F2 and F', as a further result of
through-connecting the various common conductors 6, 61, 62, and 6'.
Finally in Fig. 3 an exemplary circuit is shown, representing a
coincidence circuit, in 95 which switching units according to the
invention are provided.
The coincidence circuit of Fig. 3 consists of rectifier cells G1, G2
and G3 and switching units F, F1 and F2 according to the invention!,
ion and can be controlled at points P and Q. The outputs of the whole
arrangement are terminals R and S (which supply output voltages of
opposite polarities).
A feature of the coincidence circuit of Fig. 1o0 3 is, (in opposition
to what is known from coincidence circuits), that at terminals R and S
a switching voltage occurs which differs from normal voltage only in
case a negative potential is supplied at terminal P and simultaneously
a 110 positive voltage is supplied at terminal Q. The outputs R and S

8. may control further rectifier cell circuits by means of the output
voltages which in amplitude have been regenerated by the switching
unit FP. 115 The operation of the circuit of Fig. 3 is as follows: If
one expresses the polarity of the switching voltage, applied at the
controlling or input terminals R and Q and occurring in response 120
thereto at the controlled or output terminals R and S by means of the
signs + and - the following table can be set up, in which
corresponding voltages are shown in horizontal rows:- 125 P 0 R S + +
- + _.- + _ + + _ - - - + 130 780,003 It is supposed in this table
that terminals T and U are left unconnected, so that the same do not
influence the polarity at point N.
By means of terminals T and U circuits similar to that shown may be
connected, which thus influence, or are influenced by the latter.
In such case, terminals T and U are directly connected to the central
points of the corresponding circuits, such as point N in the circuit
shown.
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