DE1235373B - Circuit for connecting an AC voltage source to a load by means of the emitter-collector path of a transistor - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

H03k

German class: 21 al - 36/18

Number: 1235 373

File number: E 23071 VIII a / 21 al

Filing date: June 15, 1962

Open date: March 2, 1967

The invention relates to a circuit for connecting an AC voltage source to a load by means of the emitter-collector path of a transistor, the base of which is a DC switching voltage is supplied, which switches the transistor from the non-conductive to the conductive state.

AC voltages are used in control devices for machine tools, whose amplitude corresponds to a certain value and is analogous to this. It is necessary to do this Keeping analog voltages exactly proportional to the quantities they represent, while ensuring operational reliability plays a big role. In the interests of accuracy, the analog voltages are better known Way formed by selecting certain taps on autotransformers, their Winding is wound on a core of high permeability, so that the stresses at lower Impedance are formed.

It is already known to select mechanical taps on autotransformers Switch to use. However, these have the main disadvantage that they become dirty over time or wear out and therefore no longer function reliably. They also have mechanical Switch has the disadvantage that its operating speed is too slow for some areas of application.

To avoid these disadvantages the mechanical switch is already used Known transistors. A disadvantage with transistors, however, is that when you apply a Switching signal to the base a certain amount of current from the base to the emitter and to the collector flows. In the case of a core with high permeability, it is of particular importance, the direct current to be reduced to the lowest possible value by the winding, since even the lowest Direct current through the winding increases the permeability of the iron to an undesirable extent is reduced, which leads to an increase in the leakage flux and, accordingly, to an increased inaccuracy the generated analog voltages leads.

Although it is already known, a single transistor for connecting an alternating current of a transformer winding to a load. However, this is not the case Connection of several taps of a transformer winding to a load by means of a plurality of transistors, and it does not take into account the particularities described in the formation of exact analog voltages are taken into account.

The invention is based on the object, not

Circuit for turning on a
AC voltage source to a load
by means of the emitter-collector path
Transistor

Applicant:

Electric & Musical Industries Limited,

Hayes, Middlesex (Great Britain)

Representative:

Dipl.-Chem. W. Rücker, patent attorney,

Hanover, Am Klagesmarkt 10-11

Named as inventor:
Donald Ernest Tyzack, Chalfont St. Giles;

David John Abbott,

Chalfont St. Peter, Buckinghamshire

(Great Britain)

Claimed priority:
Great Britain June 16, 1961 (21778),
dated June 5, 1962 (21653)

only to replace the known mechanical switches with transistors, but also at the same time the size of the voltage passed through the transistor in the turns of the voltage source and the load to bring the flowing current to an absolute minimum. It should also be possible with transistors one of several taps on a transformer winding with a load resistor connect to.

This object is achieved according to the invention in that the AC voltage source is a tapped one Transformer winding is that the load is between the transformer winding and earth and that at least two transistors are provided, their emitter-collector paths between individual different taps of the transformer winding and earth and their bases with so high, known switching voltages are fed with potentials that are constant in relation to earth, that one of the transistors in the conductive supply

709 517/463

3 4

stand is switched, while the remaining tran- these output signals are sufficient to the bases

sistors remain in the non-conductive state. of the transistors t to such a positive value

The invention will not only bring that the transistors are blocked,
known mechanical switch by Tran- In the tripping circuits Q can be replaced by a binary versistor, but at the same time the size 5 key number in the range from "0" to "9" is fed through the transistor in the windings of the chert, whereby the digit is with the low-level transformer between the voltage source and most value in the trip circuit Q ₁ is located, the load flowing current in so strong with the next higher value in the trip switch dimensions that the permeability of the iron device Q ₂ , etc. The arrangement of the Diodes in the Maunbeeinfluenced and thus the leakage flux remains low. io trixDM is made in such a way that the voltage at the This has the result that, due to the inventive basis of that transistor t, whose index number according to the teaching according to the invention, extremely accurate analog voltage numbers stored in the tripping circuits Q can be formed. In addition, there is the advantage that the voltage of the voltage source P is equal to the possibility of connecting several taps, so that this transistor becomes conductive. All the rest of a transformer winding with a load through fifteen transistors, on the other hand, will not conduct a plurality of transistors, the disadvantages being brought about by the state due to the current the transistors avoiding flow from one or more of the trip circuits. gen Q via the associated diodes of the matrix DM

Further details, advantages and training on the bases of the transistors in question,

The following description of the embodiment example

the drawings of exemplary embodiments shown in FIG. 1 shows that the voltage,

are explained in more detail. In the drawings, the voltage in the part of the secondary winding of the transformer

dar mators T between the tap a ₀ and the one with the

Fig. 1 is the circuit diagram of a first embodiment, just conductive transistor connected tap.

example of the invention, 25 is generated, between the terminal "OFF" and earth

2 the circuit diagram of a second embodiment appears and is consequently applied to the load

example of the invention.

FIG. 3 is a graphic representation for the purpose of explaining In the exemplary embodiment described so far

The collectors of the transistors t are grounded and t change the mode of operation of the embodiment

according to Fig. 2 and 30 the emitter with the individual taps of the seconds

Fig. 4 is a somewhat more detailed circuit diagram of a primary winding of the transformer T connected. the

Part of the embodiment according to FIG. 2. Arrangement can, however, also be made so that

. Fig. 1 shows an application of the invention- the emitters of the transistors are connected to earth, while-

the circuit. An alternating voltage of z. B. rend the collectors of the transistors to the seconds

1000 Hz is fed from a reference voltage source consisting of 35 transformer windings,

to terminals »EIN« of the primary winding of a trans-

formators T applied. The secondary winding of the peak positive over earth of the over the transistor

Transformer T has ten taps a ₀ to prevent a _r ren applied alternating voltage is

These taps are equidistant from one another. it is necessary that the attached to the bases of the transistors

Each of these taps is at least as large as the emitter of a positive voltage applied

Weil assigned transistor t ₀ to i ₉ connected. is held like the peak voltage over the

The collectors of the transistors are all transistors.

on earth. The tap a _{0 of} the secondary winding of the die on the basis of FIG. 1 described invention

Transformer T is also still with the output can also z. B. as a phase reversal switch for

output terminal »OFF« connected. Use an AC voltage signal between the output 45. At this

output terminal »OFF« and earth is the load, the application is the alternating voltage signal

to which the AC voltage is connected. connected to the primary winding of a transformer

The bases of each of the transistors t ₀ to t _g , which has a secondary tapped in the middle, are via a respective resistor R with a winding. The outer ends of the secondary voltage source P for supplying a control voltage winding are connected to earth, specifically connected via the voltage, the function of which is the collector-emitter paths of a respectively assigned ter. A diode matrix DM connects the bases of the transistor. The desired output signal is transmitted to the transistors t with the output terminals of four trigger circuits Q ₁ to Q ₁ from a tap on the secondary winding to ground . In this case, each of them picks up, the phase of this output of the triggering circuits being determined by the phase of the output signals in the signal being determined by which one the transistor clock is emitting, that is, when the triggering switch is in the "O" state.

output line "0" is negative. It is not absolutely necessary that the voltage

ven potential with respect to earth and the output line source for the circuit according to FIG

direction »1« on a positive potential, while in the form of a transformer winding. Of the

"1" state of the trigger circuit The output line 60 circuit is equally usable with each

direction »0« positive and the output line »1« negative to another floating voltage source. They can also

is tive. The control voltage from the voltage switching voltages for the transistors of others

source P is negative with respect to earth, it is sufficient for circuit parts than the diode matrix described

around the transistors t when the diode matrix is ineffective. For example, the

To keep DM in the conductive state. The output 65 switching voltages for certain applications

signals of the trigger circuits Q ₁ to ß ₄ can be supplied by a ring counter, so that a

Via the diode matrix DM to the bases of the individual predetermined sequence of voltages

nen transistors t are applied. The voltages the load is applied to.

In the case of the FIG. The embodiment 7 explained in FIG. 2 and one end connection of the winding 12 according to the invention are three input terminals. The secondary winding 15 of the transformamen 1, 2 and 3 is present. The terminals 1 and 3 tor T ₅ is connected with one end to the center tap are connected to the ends of the primary winding 4 of one of the winding 4 and generated at its transformer T ₁ , while the terminal 2 5 at the other end has an output voltage that is connected to which can be removed from one end of the primary winding S of a trans output terminal 16, transformer T _{2 is} connected. The other end of the transistors A ₁ to R ₁₀ are stacked

Winding 5 is switched on with the center tap of winding 4, ie made conductive, and specifically connected. The transformer T ₁ has two seconds in that a suitable negative signal from one of the primary windings 6 and 7, the essentially ten-stage ring counter 17 from each other, is placed on the respective base and with the exception of those explained below. One of the ring counter 17 abbeommezelheiten are identical. Both secondary windings 6 ner pulse is passed twice per period via a gate and 7 have the same number of turns as 19 to a further ring counter 18. From the winding 4, however, the ring counter 18 shown in the drawing shows negative signals at the winding 7 with a winding direction opposite to the winding 6, the bases of the transistors S ₁ to S _{13 are} shown around these opposite winding directions. To make the winding conductive and thus short-circuit. Here ment 6 is provided with seven connections, namely the ring counter 18 is connected so that the negative taps at the two end connections and five other, equal signals in pairs always to those transistors S moderately distant from each other. As a result, the index numbers of which are applied directly to the winding 6 in six equal sections 20 one after the other. In other words, they are subdivided. The winding 7 is connected with six taps, the transistors S ₁ and S ₂ , then the transistors, which are evenly spaced along the disruptive S ₂ and S ₃ , then the transistors S ₂ and S ₄ etc. and the winding the taps are fed. The ring counter 17 will be seen through pulses from the sections into which the winding actuated a suitable pulse generator, 6 is divided. 25 To explain how the device works

The transformer T ₂ has eleven secondary windings according to FIG. 2 should be on FIG. 3, reference is made to 8, which are connected to the taps of the winding 6.

or connected to the taps of the winding 7. It is assumed that alternations are in phase. For the sake of clarity, voltages of z. B. 100 Hz, which represent the coordinates of the graphic representation of the individual seconds Z ₁ , Z ₂ and Z ₃ , in which the terminal windings of the transformer T _{2 are applied} separately from 1, 2 and 3 respectively. This represents the presented to each other. The number of turns of the secondary voltage at the center of the winding 4 the value of the windings 8 depend on the square of the electrical '/ 2 (Z ₁ -FZ ₃ ), hence the ordinate at point D see the voltage of the tap of the windings 6 in FIG . 3. It is now further assumed that or 7 from, to which the windings 8 are connected 35, the voltage at the output terminal 16 is paras, so that at In, turns for the winding-unbolic arc ABC in FIG. 3 are described should, gen 6 and 7 are the number of turns of those of the winding, specifically with reference to a parameter t. While lungs 8, which is located at a tap, according to the description of this parabolic arc werj, _λτ λ, r ^s \ .,. -. ,. . . _ΛΓ j. , ,, the sixty pulses to the ring counter 17 and twelve pressure N [I - ^) results. Here, N is the number of _{40 pulses from} ⁶ _{m slow counter 17 to long counter} 8.

of the turns of the winding 5. conducts. These impulses correspond to growth rates of

The windings 8 and the end connections of each of a unit of the parameter t. Winding6 are shown in the drawing. For i = 0, ie at the beginning of the description of the th way via the collector-emitter paths of the arc ABC, the transistors A ₁ , S ₁ and S _{2 are} transistors S ₁ , S ₂ , S ₃ ... S _{13 put} to earth. 45 conductive. As a result, there is a current path from earth The taps of the windings 6 and 7 are connected to the transformers T ₃ and _{T 3 and through the transistor S 1} , the upper half of the winding end connections of the primary windings 9 and 10 of the development 6, the winding 13 and the transistor R ₁ T ₁ connected. The second back to earth. This means that the voltage generated in the winding 11 of the transformer T ₃ , the four fifths 15, is equal to the voltage generated over half the number of turns of the primary winding 9 50 upper half of the winding 6, is by means of three taps the windings 13 and 15 are divided into four equal turns. The three taps and the two have number. Because the winding 6 continues to have the end connections of the winding 11 over the same number of turns as the winding 4, the lektor-emitter path of the transistors A ₁ to R _{5 is connected} to the voltage across half the winding t. The secondary winding 12 of the transformer 55 equals 72 (X ₁ -X ₃ ). It therefore follows that in the state T ₁ also has a number of turns of four i = 0 at the output terminal 16 a voltage fifth of the number of turns of the assigned

th primary winding 10. The secondary winding 12 is ¹ A (X ₁ -IZ ₃ ) + '/ 2 (Z ₁ -Z ₃ ) = Z ₁

continues to adjust by means of three taps in four.

divided into equal sections, the three taps 60 for t = 1, ie after the first pulse has been applied

together with the two end connections via the to the ring counter 17, the transistors R ₂ , S ₁

Collector-emitter paths of the transistors R ₆ to R ₁₀ and S ₂ conductive, so that a quarter of the winding 11 in

lying on earth. the circuit containing the winding 13

The primary winding 13 of a further transformer is switched. Above the winding 13 there are four

mators T ₅ lies between the midpoint of the winding 65 fifths of the difference in voltage between the

ment 6 and one end connection of the winding 11. Centers of the windings 6 and 7 are generated. There

Another primary winding 14 of the transforma- now the windings 6 and 8 or 7 and 8 together

tors T ₅ is between a center tap of the winding form the tendon (as described in detail, for example, on the hand

Claims (3)

the F i g. 1 of the description of British patent specification 796 994 is explained), it follows that the center z. B. the winding 6 generated voltage when one of the transistors S1, S2, S3, S5, S7, S9, Sn or S13 is conductive, proportional to the difference in the ordinate height between the point D in FIG. 3 and that point on the parabolic arc ABC which corresponds to the transistor that is currently conducting. Accordingly, the voltage generated across the winding 9 in the state t = 1 is proportional to the difference in the height of the ordinates between the point A and the point E, whose abscissa distance from point., 4 is one twelfth of the total abscissa length t of the arc ABC. The voltage generated at the output terminal 16 in the state i = 1 therefore represents the ordinate of a point which is one fifth (namely one quarter of four fifths) along the chord AE of the parabolic arc ABC. In the states i = 2, t = 2> and i = 4, the output voltage at terminal 16 follows the ordinate of a point that is two fifths, three fifths or four fifths away from point A along the chord AE . In the state i = 1, the transistors R6, S2 and S3 are in the conductive state, and the voltage at the terminal 16 represents the ordinate of the point E. The winding 15 is now fed from the winding 14. When the subsequent states pass through up to t = 9, the output voltage at terminal 16 represents the ordinate values of successive points which lie on a second chord of arc ABC starting from point E and in turn one twelfth of the entire abscissa length in the abscissa. It can be seen that in the manner described above, when the states from i = 0 to i = 60 are passed through, voltages are generated at the output terminal 16 which represent the ordinates of points on a series of chords which define the arc ABC. In Fig. 4, the ring counters 17 and 18 with the interposed gate 19 are shown in detail. The ring counter 17 has ten levels. It can be of any type that is suitable for successively supplying a constant negative output voltage for connection to the individual transistors R at the individual stages. The ring counter 17 counts the pulses from the generator 20, the pulse repetition frequency of which can be changed so that the rate of change of the parameter t and consequently the speed of the description of the sheet A B C by the interpolator can be adapted to the respective conditions. Twice per counting period, a pulse is taken from the ring counter 17 and sent to the ring counter 18 via the “OR” gate 19. The ring counter 18 can generally be of the same or any other design as the ring counter 17. The output signal of each stage of the ring counter 18 is applied via two suitably polarized diodes to the bases of a pair of transistors S, two transistors S with consecutive index numbers being one Pair. In principle, only a relatively small negative voltage is necessary to bring the transistors R and S into the conductive state. However, those transistors that do not need to be in the conductive state should have a positive bias at the base that is at least equal to the maximum positive voltage swing at their collectors, so that these transistors are prevented from conducting when their collector is positive. The ring counters 17 and 18 are therefore designed so that they supply the necessary voltage swing for the bases of those transistors which are to be switched into the conductive state. In general, continuous interpolation over a series of points is required, the points being grouped into groups of three, each group having a point in common with the next group. In order to achieve this, it is expedient to provide a second interpolator and to allow the two interpolators to overlap, the output voltages from both interpolators being switched on in a suitable manner. In such a case, the voltage at point 21 in ring counter 18 can be used to start the interpolation by the second interpolator by applying a pulse to the second interpolator at a point which is shown in FIG. 4 for the first interpolator Digit 22 corresponds. It should also be noted that if no pulse passes through the ring counter 18, no voltage is generated across the winding 15 either. If an interpolator constructed in accordance with the present invention is used for the automatic control of machine tools, a separate interpolator should be used for each coordinate for which interpolation is required. The ring counters 18 and 19 can, however, be assigned jointly to the existing interpolators. Patent claims: 1. Circuit for connecting an AC voltage source to a load by means of the Emitter-collector path of a transistor whose base is supplied with a DC switching voltage that switches the transistor from the non-conductive to the conductive state, thereby characterized in that the AC voltage source is a transformer winding with multiple taps that the load between the transformer winding and earth and that at least two transistors are provided are whose emitter-collector routes between individual different taps of the Transformer winding and earth lie and their bases with such high, known per se Switching voltages are fed with potentials that are constant with respect to earth, that one of the Transistors in the conductive state is switched, while the other transistors in remain non-conductive. 2. Circuit according to claim 1, characterized in that the electrodes of the transistors are grounded, the connecting layers of which with the associated base electrodes are the larger are. 3. Circuit according to claim 1 or 2, characterized in that the bases of the transistors each connected via resistors to a grounded voltage source of constant voltage are that the transistors are in conductive