DE2203952B2 - Projector for diapositive slides - uses digital analogue transducer with two decade stages connected to semiconductors control electrodes - Google Patents

Abstract

The apparatus changes the slides without causing mechanical shocks. According to the position of the magazine, a voltage of a first voltage series is connected to the input of a first comparator device via a semi-conductor of the first decade stage and a voltage of a second voltage series is connected via a semiconductor of the second decade stage. Each stage is higher than the next by a factor of 10. A comparator is connected with a further comparator whose further input can be connected via selecting keys with the first or second decade voltage series, which determines the fixed position of the magazine.

Description

14. Slide projection device according to one of the indicator circuit with respect to the possible preceding claims, characterized thereby, given a lower limit steps for the magazine, draws that from the output of the second opera- Accordingly, the control device is not for belietionsträger (105) for the digital-analog wall 30 big many slides can be laid out.

A feedback connection is provided. The invention is based on the object

is, through which the converter to forward or a slide projection device of the aforementioned

Down counting is adjustable. to create the highest type, which, while avoiding the

15. Slide projection device according to one of the parts of the known device and in the case of the previous one Claims, characterized by a characteristic training as simple and functional as possible, that the impulse device should be constructed in a way that is safe. Also seeks the crfinding switch (11, 12, 13, 14, 15), due to the corresponding slide projection device at cheaper a bistable multivibrator (16) can be influenced. Work training as precisely as possible. Furthermore should

16. Slide projection device should be as bounce-free as possible after the pulse device. Also claim 15, characterized in that the slide projection device should be able to be designed for any number of switches, three contact springs (13, 14, 15) and two slides. Furthermore, a circular, concentric small number of keys on a disk (10) should be used,
According to the invention, this is achieved in that face contact tracks (11, 12), one of which has the adjusting device a digital-to-analog converter contact track (11) over which a contact spring (13) 45, which in a known manner has a first one with an input of the flip-flop (16) and at least one second decade stage, the other contact track (12) of which via the second that the outputs of each decade stage with control contact spring (15) with a second input Electrodes of controllable semiconductor switching elements of the flip-flop (16) is connected, that the third are connected, that according to the position of the contact spring (14) alternately with the first element provided in the plane 50 of the magazine via one semiconductor switching of the two contact paths Decade stage a voltage value clock approaches (11a, 12a) of the first and two - an equal first voltage series on a th contact track (11, 12) in V connection is available, so that the input of a first comparison device is present that when the contact disk (10) is rotated over and over a semiconductor switching element of the third contact spring (14) alternately the one second decade stage a voltage value of an equal and the other input of the flip-flop stage ( 16) with stepped second voltage series, the voltage of which is connected to a fixed potential. per level is ten times greater than the level

17. Slide projection device after tensioning the first series of voltages, on the next Claim 16, characterized in that the input of the first comparison device is present that Sets (11a) of one contact track (11) offset 60 the output of the first comparison device are opposite to the approaches (12a) of the other one input of a further comparison device contact track (12). device is connected, the other input via

Selector keys with at least one of the voltage series

corresponding to the first or second decade, the

In the case of such a known slide projection setting, which determines the desired position of the magazine, at least four rows can be connected for control purposes, and that depending on the lais provided, whereby the power consumption of the selected magazine compartment is detrimental to the semiconductor switching is increased. The motor for the magazine elements of the first and possibly the second

Decade stages are switched through one after the other. Semiconductor switching elements are particularly suitable

until at the same voltages at the input of the ders advantageously field effect transistors. Further comparison device the servomotor and expediently the switches of the selector

the pulse device can be stopped. device relay contacts, their relays through the

Depending on the position of the magazine, 5 selection keys can be influenced.

a semiconductor switching element of the first decade stage

and a semiconductor switching element of the second Deka training operational amplifier, whose Denstufe controlled through, so that between the two gain factors by providing inputs of the same size of the first comparison device one the ßen resistors in the input branches and in relevant magazine compartment characterizing span io feedback branch is approximately equal to one. voltage is present. If a certain magazine subject is now According to further training, in the starting

selected by pressing a selector button, the second operational amplifier is set in motion by two transid drive motors and the magazine is provided with stor-controlled relays through which the trans is transported forwards or backwards. In the case of the transport motor for the forward and backward transport of the magazine of the magazine by one magazine compartment, interest is controllable.

a pulse is fed to the digital-to-analog converter, according to a further development, the resistance

which is connected to a continuous through-connection of the semiconductor chain of the selection device to the plus and minus switching elements of the first decade stage and, on the other hand, to a voltage source. Farther at least the second decade stage. At the selector switch of the first decade, a potential-voltage equality is applied to the same inputs of the "o tial, the drive potential of the voltage source is shut down to the value zero compared to the plus and minus second comparison device. shows. In addition, the selector switches are the second

According to a further development, the second decade points directly to the further input of the second denstufe an additional semiconductor switching element operational amplifier connected. The first entrance as well as an additional switch, the 25 of the second operational amplifier is on the other hand when the magazine is only assigned to the first decade, the output of the first operational amplifier is activated, and when it is activated, the linked. As a result, there is advantageously no Influence of the voltage series of the second decade auxiliary comparison device required, stage at the output of the first comparison device is also advantageously from the output

is canceled. If one of the first ten 30 of the second operational amplifier for digital ana slides is in the ready position for projection, the log converter provides a feedback connection to see the additional semiconductor switching element and the one through which the converter is switched to forward or additional switches for the second decade stage can be set to count down. makes. To achieve bounce-free pulses, the

According to a further embodiment, the voltage pulse device is a switch, through which row of the first and second decade stage can be influenced by a bistable multivibrator. Formed in an advantageous resistance chain that consists of ten equally large ways, the changeover switch has three contact springs ßen resistors of the first decade stage and off and two circular, concentric on a disc Resistors of the second decade stage are arranged and rotatable by the transport motor whose resistance value by a factor of ten greater than 40 contact tracks, whose one contact track over the is as the resistance values of the first decade stage, a contact spring with a first input the taps between the resistors with flip-flop and their other contact path over the the one output electrode of the semiconductor switching second contact spring with a second input of the elements are connected, while the other flip-flop is connected. The third contact spring The input electrodes of the semiconductor switching elements are arranged alternately with are brought together in the plane of the two types of condens and are connected to rectangular contact paths provided in each case at an input of a comparison device and the first and second contact paths are connected. manure, so that when the contact disc is rotated over

According to another advantageous embodiment, the third contact spring alternately one and the other possibility to connect the voltage series of the first and 50 other inputs of the trigger stage with a fixed power-wide decade stage from separate voltage tial. The approaches of the one contact divider stages are bathed, each semiconductor switching path being offset with respect to the approaches of the other element is assigned voltage divider. The clamping contact path is arranged kade a common resistor, which has the consequence that disturbances in counting and transponder semiconductor switching elements are largely avoided in each case, a discrete process. Resistance can be switched on. In the following, the invention is based on two.

Resistance of the first decade level facing in F i g. 1 to S shown Ausführungsbeispiek Connections of the divider resistors are described with one. Show it

Input and the common resistance of δο F1 g. 1 to 3 a first exemplary embodiment urk the connections of FIG. 2 facing the second decade stage. 4 and S a second example.

Divider resistors with the second input of the first According to FIG. 1 is designated with 1 a slide projector Comparison device connected. net. In a magazine guide 2 of the slide projector 1 is

The switches of a magazine 3 in which slides 4 are to be found are then advantageously used Selection device with a separate resistance 65 By a transport motor 5 is via a screw « chain connected for the first and second decade, where a pinion 8 engaging in a toothed bar 7 drives with the voltage levels those of the decade levels bar. By the transport motor S the Magazii correspond. step by step for each magazine compartment optionally into the eim

or transported in another direction. Through an in Known way controlled change slide 9 is when the magazine 3 is at a standstill in the projection standby position slide 4 * off the magazine compartment 3 χ brought into a projection position and after the slide has been projected 4 χ returned to the magazine compartment.

According to FIGS. 1 and 1 a, a disk 10, which has two circular contact tracks 11 and 12, can be driven by the drive motor 5. These are arranged concentrically to the axis of rotation of the disk 10. Both contact tracks 11 and 12 each have at equal intervals 11 a and 12 a, which lie in the plane of the contact tracks 11 and 12. the Contact track 11 works with a contact spring 13, the contact track 12 with a contact spring 14, while the Kontaktansätzella and 12a with a contact spring 15 work together.

The contact springs 13 and 14 are connected to two inputs of a bistable flip-flop 16. the Contact spring 15 is connected to the negative pole of a voltage source 17.

The drive motor 5 is located in a circuit formed from the voltage source 17 and from two changeover switches 18, 19 and 20, 21.

The output of the bistable multivibrator 16 is shown in FIGS. 1 and 2 connected to the input of a digital-to-analog converter via the connection points EE. This consists of a first digital stage 22 for the first decade, a second digital stage 23 for the second decade, a first analog stage 24 for the first decade and a second analog stage 25 for the second decade. The two digital stages each consist of four bistable multivibrators 26, 27, 28, 29 or 30, 31, 32 and 33. All bistable multivibrators 26 to 33 can be transferred to a defined starting position by means of a button 34. The output of each bistable multivibrator 26 or 27 or 28 or 29 of the first digital decade stage leads to its own collecting line, from which a connection to the input of a gate G1 or G 2 or G 3 or G 4 or G 5 or G6 or G7 or G8 or G9 or GO leads. Connections lead from gates Gl to GO to transistors 35, 36, 37, 38, 39, 40, 41, 42, 43 and 44.

In the same way as with the first digital level 22, the outputs of the bistable multivibrators 30 to 33 of the second digital stage are connected to bus lines, each with an input a gate GOO or GlO or G 20 or G 30 or G 40 ... or G90 are connected. From gates GOO to G90 lead connections to transistors 45, 46, 47, 48, 49 ... and 50.

The emitters of all transistors 35 to 44 and 45 to 50 are brought together and at the potential Connected zero. Resistors 51, 52, 53 are located in the collector branches of transistors 35 to 50. 54, 55, 56, 57, 58, 59, 60 and 61 as well as 62, 63, 64 and 65 arranged. Since it is assumed in the exemplary embodiments that at most 50 slides should be shown, only the the magazine compartments or slides 10 to 40 counting gates G10 to G40 of the second decade stage activated. The GOO gate is assigned to the zero step of the second decade stage. This is effective when the magazine compartments or slide positive ones one to ten are counted or presented should.

The collectors of the transistors 50 following the transistor 49 are all with the collector of transistor 49 connected. From the collector of transistor 35 there is a connection to the gate of a field effect transistor 66, from the collector of transistor 36 a connection to the gate of a field effect transistor 67, from the collector of transistor 37 a connection to the gate of a field effect transistor 68, from the collector of transistor 38 a connection to the gate of a field effect transistor 69, from Collector of transistor 39 connects to the gate of a field effect transistor 70, from the collector of the Transistor 40 connects to the gate of a field effect transistor 71, from the collector of transistor 41 a connection to the gate of a field effect transistor 72, from the collector of transistor 42 a connection to the gate of a field effect transistor 73, from

»O collector of transistor 43 connected to the Gate of a field effect transistor 74 and from the collector of transistor 44 a connection to the gate of a Field effect transistor 75. The sources of the field effect transistors 66 to 75 are together-

»5 out and connected to a junction A 2. A connection leads from the collector of transistor 45 of the second decade stage to the gate of a field effect transistor 76, from the collector of transistor 46 a connection leads to the gate of a field effect transistor 77, from the collector of transistor 47 a connection leads to the gate of a field effect transistor 78, and from the collector of transistor 48 a connection to the gate of a field effect transistor 79 and from the KoI-lektor of the transistor 49 a connection to the gate of a field effect transistor 80. The sources of the field effect transistors 76 to 80 are brought together and connected to a connection point A 4.

A voltage divider consisting of a chain of resistors has ten for the first decade stage equal resistors 81, 82, 83, 84, 85, 86, 87, 88, 89 and 90 are connected to the buttons Π, Γ2, Γ3, Γ4, TS, Γ6, Γ7, Γ8, Γ9 and TO . The sides of the keys Tl to Γ0 facing away from the resistors 81 to 90 are brought together and with a connection point A 1 connected. Further resistors 91, 92, 93, 94 and 95 are connected in series with resistors 81 to 90. The resistors 91 to 94 are the same size and have resistance values that are ten times greater than

so are the resistance values of the individual resistors 81 to 90, resistors 91 to 94 are assigned to the second decade stage. At these resistances are Keys ΓΟΟ, ΓΙΟ. Γ20, Γ30, Γ40 connected The sides facing away from resistors 91 to 94

SS of the keys Γ00 to Γ40 are brought together and connected to a connection point A 3.

The sinks (drains) of the field effect transistors 6 < to 75 are with the taps of the first Deka the stage associated resistors 81 to 90 verbun the. Also are the sinks of the field effect transi disturb 76 to 80 with the taps of the second « Resistors 91 to 9 assigned to the decade stage! tied together. From the resistors 81 to 91 existing chain of resistance lies on one side Minus potential and zero on the other side Potential.

According to FIG. 3 are the sources of the second! Field effect transistors 7 <assigned to the decade stage

9 10

to 80 via the connection point A 4 and via a de-energized state of the two relays 110 and

Resistor 101 with a first input of an Ope- 111 are the changeover switches 18, 19 or 20, 1 \

ration amplifier 102 connected. The sources def in the position shown in FIG. 1. Accordingly, it is located

the field effect assigned to the first decade stage - the motor 5 is at a standstill,

transistors are on the junction A 2 and 5 should now z. B. the 10th magazine compartment in the ready

are brought to the shaft position via a resistor 100 with the second input, the key Γ0

of the operational amplifier 102 connected. A reverse actuated. The Γ00 key remains pressed while the

coupling resistance, which has the same size button Tl is opened. As a result, the span increases

like the two resistors 101 and 100, with 103 voltage between the connection points A 3 and A 1 to

designated. The output of the operational amplifier io nine voltage units to ten times the voltage

102 is on via a resistor 104 with a first voltage value. The consequence is that the balance

Input of a second operational amplifier 105 ver at the second operational amplifier 105 is disturbed and

bound. A feedback resistor that the transistor 108 through for feedforward control.

is the same size as the resistor 104, is controlled. The relay 110 is energized and the con-

denoted by 106. 15 clock 18 of the switch 18, 19 closed. The arrival

The buttons Γ00 to Γ 40 of the second decade drive motor 5 receives voltage and rotates in the

stage are via the connection point A 3 and a sense of a forward movement of the magazine 3. At

Resistance 98 with the first input of an opera- the forward movement of the magazine 3 is at

tion amplifier 97 connected. The keys Π to Γ 0 advance from magazine compartment to magazine compartment

the first decade stage are connected via the connection point% a pulse disc 10 are each a pulse to the bi-

A 1 and given via a resistor 96 to the second stable multivibrator 16.

Input of the operational amplifier 97 connected. now the field effect transistors 67, 68, 69, 70, 71,

A feedback resistor is labeled 99. 72, 73, 74 and 75 open. In the case of

This has the same size as the counter-control of a field-effect transistor is before

would be 96 and 98. The output of the operational control »5 controlled field effect transistor blocked, so that

The amplifier 97 is connected via a resistor 107 to the field effect transistors 66 to 74 which are activated

second input of the second operational amplifier are blocked. Is now the field effect transistor 75

105 connected. Controlled by the output of the second opera, the voltage across the two is

tion amplifier 105 carries a common connection to inputs of the second operational amplifier 105

connection to the bases of two transistors 108 and 109. 30 equal in size. As a result, transistor 108 is again

In the collector circuit of the transistor 108, a relay is blocked and the relay 110 is de-energized. The tran-

110 and in the collector circuit of the transistor 109 a sistor 109 was previously in the blocking state and demzu-Relaislll arranged. The relay 110 is de-energized with the result of the relay 111 The drive motor5 Positive pole of a voltage source 112 and the relay is shut down, since the contacts 19 and 21 of the reverse

111 with the minus pole of a further voltage switch 35 18, 19 and 20, 21 are closed.

source 113 connected. Both voltage sources 112 via the connection points A 5 and the diode 114 and 113 are connected in series. The emitters of both had previously been reported to the digital-to-analog converter.Transistors 108 and 109 have been merged so that this has to count in the forward direction with a tap between the two voltage target now connected to the 25 magazine compartment in standby sources 112 and 113. The relay 110 and 40 are transferred to the buttons Γ 20 111, the urn switches 18, 19 and 20, 21 pull and Γ5 are operated. . The voltage between the two ^{one, n, e} -? ', · .. aj _Λ inputs of the second operational amplifier 105. Furthermore, RST, the output of the second operational has then a value which is equal to fifteen clamping amplifier 105 via the connection point AS and units is. The relay 110 is energized again,

^a ? £ "? } ^With λ" ^ ^lta ! ^{en stages 22 45 and the contact} Ι »of the changeover switch 18, 19

and 23 connected for the first and second decades. closed. The result is that the motor 5 is again in

This feedback connection has the task of moving the magazine forward 3 in to indicate to the signal-to-analog converter whether this rotation is offset. One import is required for each magazine compartment

forwards or backwards »« * should pay. _pu j _{s mm bistabüen} multivibrator 16 released.

The mode of operation is now as follows: ⁵ ° ^{With the first} pulse, the field effect transistor is 75

_. . . _o .. ^, locked and the field effect transistor 77 the second »

It is assumed that the keys Π and decade stage durtAgesteueVtBe with the second b

designated first magazine compartment or the first dia- rend of the field effect transistor 77 remains through, positive m emer preparation position is 55 Successively onlyf the FddeSttransistors As a result, the field effect transistors 66 and 76 67 to 75 are checked. BeTmΓ111 pulse is det

SSSSSSSSS5

toige sina die Keiais in una 111 aberregL 6ς

⁶ ' ³ ^ "" voltage units reduced. The result is

that the transistor 109 is turned on and the relay 111 is energized. The contact 20 of the changeover switch 20, 21 is closed and the motor S is set in rotation. The direction of rotation of the motor 5 is now reversed as in the previously assumed case. Via the connection points A 5 and the diode 114, the digital-to-analog converter is notified that it has to count down. With each pulse, the voltage at the first input of the second operational amplifier 105 is reduced by one voltage unit. In the balanced state, the field effect transistors 76 and 75 are turned on, while the other field effect transistors are blocked. If the 10th magazine compartment is in the ready position, the transistor 109 is blocked and the relay 111 is de-energized. The motor 5 is again at a standstill.

The second exemplary embodiment is designed similarly to the first exemplary embodiment. The single ones Elements that correspond to the individual parts according to the first embodiment are identical Provided with reference numerals. They are only for different identification with an index Mistake. Different is z. B. that all sinks of the field effect transistors 66 'to 80' together are connected to zero potential. With the sources of the field effect transistors 66 'to 75' of the first decade stage is a resistor 120 or 121 or 122 or 123 or 124 or 125 or 126 or 127 or 128 connected. The source of the field effect transistor 75 'does not contain a resistor. All resistors 120 to 128 form a voltage divider with a common resistor 129. The resistors 120 to 128 are chosen so that when the field effect transistors are driven through one after the other 66 'to 75' the voltage at the divider tap changes by one voltage unit. This divider tap is connected to the connection point A 2 '.

Resistors 130, 131, 132, 133 and 134 are connected to the sources of the field effect transistors 76 'to 80' of the second decade stage. These contradictions 130 to 134 together with a common resistor 135 form a voltage divider, ίο The resistors 130 to 134 are chosen so that when the field effect transistors 76 'to 80' are sequentially controlled, the voltage at the divider tap changes by ten voltage units. This divider tap is connected to the connection point A 4 '. In this embodiment too, only one field effect transistor is always turned on in each decade stage.

The resistor chain 81 'to 95' connected to the keys TV to Γ0 'and Γ00' to Γ40 'is designed in exactly the same way as the resistor chain according to the first exemplary embodiment. The only difference is that there is a minus potential at one end of the resistor chain and a plus potential at the other end of the resistor chain. A white terer difference is that the connection point AV is not connected to the input of an operational amplifier. At the connection point A 1, the potential is zero. The connection point A 3 is connected to the resistor 107 ' directly ver with the second input of the second operational amplifier 105'.

The functioning of the second Ausführungsbei game is the same as in the first embodiment example.

For this purpose 4 sheets of drawings

Claims (13)

Patent claims: 1. Slide projection device with a slide projector which has a transport motor for the forward and backward transport of a magazine and a pulse device that generates a pulse for each magazine compartment or for each slide in the magazine that passes a fixed point during transport of the magazine and with a control device which has a selection device for the selection of a magazine compartment or a slide, an adjusting device which can be influenced by the pulse device and which compares a preset selected variable with a manipulated variable determined by the adjusting device, the control device causing the magazine to be shut down if they are the same, when the preselected magazine compartment or the preselected slide has reached a ready-for-projection position, characterized in that the actuating device has a digital-to-analog converter which, in a manner known per se, has a first and at least one second decade stage (22, 24 and 23 , 25) has that the outputs of each decade stage (22. 24 or 23, 25) as are connected to control electrodes of controllable semiconductor switching elements (66 to 75 and 76 to 80) that according to the position of the magazine (3) via a semiconductor switching element (z. B. 66) of the first decade stage (22, 24) a voltage value of an equal first voltage series (81 to 90) is applied to one input of a first comparison device (102) and via a respective semiconductor switching element (e.g. 76) of the second decade stage (23, 25) a voltage value of a similar second voltage series (91 to 95), the voltage of which per step is ten times greater than the step voltage of the first voltage series, is present at the further input of the first comparison device (102) that the output of the first comparison device (102) with one input of a further comparison device (105) is connected, the further input of which is connected to at least one of the voltage series of the first and two via selection keys (T1 to 0 and Γ00 to Γ40) The voltage series corresponding to the ten decade and determining the target position of the magazine (3) can be connected, and that, depending on the magazine compartment selected, the semiconductor switching elements of the first and possibly the second decade level are switched through one after the other until the voltages at the input of the further comparison device (105 ) the servomotor (5) and the pulse device (10) are stopped. 2. Slide projection device according to claim 1, characterized in that the second decade stage (25) is an additional semiconductor switching element (76) as well as an additional switch (TOO) which is actuated when the magazine compartments are only assigned to the first decade and when whose actuation the influence of the voltage series of the second decade stage at the output of the first comparison device (102) is canceled. 3. Slide projection device according to claim 1 or 2, characterized in that the voltage series of the first and second decade stages (24 25) is formed by a resistor chain, consisting of ten equal resistors (81 to 90) of the first decade stage and ten larger, equal resistors (91 to 95) of the second decade stage that the taps between the resistors are connected to one of the output electrodes of the semiconductor switching elements (66 to 75 and 76 to 80), while the other output electrodes of the semiconductor switching elements are brought together for decades and are each connected to an input (A 2 to A 4) of the comparison device (102) . 4. Slide projection device according to claim 3, characterized in that the taps between the resistors of the resistor chain with switches (Γ1 to Γ0 and Γ00 to Γ40) are connected, the sides facing away from the resistors are brought together, and that the switches of the resistor chain of the first decade with one input (A 1) of an auxiliary comparison device (97) and the switches of the resistor chain of the second decade are connected to the other input (A 3) of the auxiliary comparison device (97). 5. Slide projection device according to claim 1 or 2, characterized in that the voltage series of the first and second decade stages are formed from separate voltage divider stages (120/129 to 129 and 130/135 to 134/135), each semiconductor switching element being assigned a voltage divider. 6. Slide projection device according to claim 5, characterized in that the voltage divider each decade have a common resistor (129 or 135) to which a resistor (120, 121 ... or 130, 131 ...) can be switched on. 7. Slide projection device according to claim 5 or 6, characterized in that the connections of the divider resistors (120 to 128) facing the common resistor (129) of the first decade stage (24 ') to one input (A 2') and to the common resistor (135) of the second decade stage (25 ') facing terminals of the divider resistors (130 to 134) are connected to the second input (A 4') of the first comparison device (102 '). 8. Slide projection device according to one of claims 5 to 7, characterized in that the switches (Γ1 to Γ0 and Γ00 to Γ40) of the selector with a separate resistor chain (81 'to 95') for the first and second Decade are connected, the voltage levels corresponding to those of the voltage divider of the decade level. 9. Slide projection device according to one of the preceding claims, characterized in that the semiconductor switching elements are field effect transistors. 10. Slide projection device according to one of the preceding claims, characterized in that the switches of the selection device Relay contacts are whose relays can be influenced by the selection keys. 11. Slide projection device according to one of the preceding claims, characterized shows that the comparison device Opera- transport is in a öonsverstarker are arranged whose gain factor th circuit, through the contact f ™? ^ TS ^ ^ ^g ί ^{large forest residues of} a control relay, due to the contact of a drive ilOO 101, 103) in the input branches and in for the slide change process and through the contact Feedback branch approximately glet * one is influenced by 5 of the relay for changing the direction of rotation 12. Dmprojeknonseinrichtun? after one of the will. An electro-preceding one serves as a comparison device Claims, characterized by a magnetic NuU indicator circuit, the two relays draws that in the output circuit of the second OPE and contains their contacts. A tracking switch rationsveirstarkers (105) two transistor-controlled is controlled by the magazine movement, whereby (108, 109) relays (110, 111) are provided, 10 a gear is necessary that through each magazine the transport motor (5) for the advance, the further switching of a rotary switch and return transport of the magazine (3) is controllable. by one step. A relay receives 13. Slide projection device according to one of the interacting with drive-dependent switches to claims 5 to Ϊ2, characterized in that by closing the control circuit, the resistor chain of the selection device on the 15 resolved selection process upright to completion. The zero indicator circuit has resistor chains connected to the selector switch (TV except, which must be dimensioned in such a way that the indicator relay is applied through the Γ0 ') of the first decade The current flowing is always the same or that is greater than the pull-in current of the relay compared to the plus and MLius potential. As a result, the voltage source has the value zero and 20, the individual resistances of the resistor chains that the selector switches (00 'to Γ40') of the second cannot be made arbitrarily large. Also decade can be provided directly with the further input of the not as many resistors as desired, second operational amplifier (10S ') connected since at least the pull-in current of the relay is in one, during the first input of the operational case and in the other case one by the number of Amplifier (105 ') is connected to the output of the first 25 resistors increased current flow through the relay operational amplifier (102'). got to. Accordingly, is for a functionally reliable work