DE2203952C3 - Slide projection device - Google Patents

Description

is. through which the converter can be set to count up or down.

15. Slide projection device according to one of the

got to. Accordingly, for a functionally reliable operation of the indicator circuit with respect to the possible Steps given a lower limit for the magazine.

-. As a result, the control device is not

tion amplifier (105) for digital-analog wall 30 big many slides can be designed. ler a feedback connection provided The invention is now based on the object

To create a slide projection device of the type mentioned at the outset, while avoiding the disadvantages the known device and with fully electric

previous claims, characterized by a characteristic training that is as simple and functional as possible, that the impulse device should be constructed in a way that is safe. Also should the invention 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 40 should be the slide projection device for any number switch three contact springs (13, 14, 15) and two slides can be interpreted. Furthermore, a circular, concentric on a disc (10) small number of buttons are used, arranged, by the transport motor (5) rotating- According to the invention this is achieved in that has bare contact tracks (11, 12), one of which is the actuating device a digital-to-analog converter Contact track (11) on which a contact spring (13) 45 has a first in a known manner

and at least a second decade stage that the outputs of each decade stage with control electrodes of controllable semiconductor switching elements

vw ... _{rr v} -, -., _._ th are connected that according to the position

Contact spring (14) alternating with in the plane 5 ° of the magazine via a semiconductor switch Both contact paths provided a voltage value for the first decade stage element

an equal first voltage series is applied to an input of a first comparison device

uiu ^ w ~ .w.— _ö - _v __, and each with a semiconductor switching element of the

the third contact spring (14) alternately the one 55 second decade stage a voltage value of an equal and the other input of the flip-flop (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 voi direction is applied that sentences (Ha) of the one contact track (11) offset 60 the output of the first comparison device

one input of a further comparison device is connected, the entrance of which is via

Selector keys with at least one of the voltage series

corresponding to the first or second decade, the

In such a known Diaprojektionsein- G ₅ target position of the magazine fixing voltage: Pla are for control purposes at least four re- series connected, and that provided in response to the IS, whereby power consumption loading the selected magazine compartment, the semiconductor Schaltichtlich is increased. The motor for the magazine elements of the first and possibly the second

with a first input of the flip-flop (16) and its other contact track (12) via the second Contact spring (15) is connected to a second input of the flip-flop (16) that the third

clock approaches (Ha, 12a) of the first and second contact tracks (11, 12) is connected, so that upon rotation of the contact disc (10) over

are opposite the approaches (12 a) of the other contact track (12).

Decade stages can be switched through one after the other until the voltages at the input of the further comparison device, the servomotor and the pulse device are stopped.

Depending on the position of the magazine, a semiconductor switching element is in the first decade stage and a semiconductor switching element of the second decade stage controlled so that between the two Inputs of the first comparison device a voltage characterizing the relevant magazine compartment is applied. If a certain magazine compartment is now selected by pressing a selection key, then the drive motor is started and the magazine is transported forwards or backwards. When moving of the magazine by one magazine compartment, a pulse is fed to the digital-to-analog converter, the continuous switching through of the semiconductor switching elements of the first decade stage and possibly the second decade stage. If the voltage is the same at the same inputs of the second comparison device, the drive motor is stopped.

According to a further embodiment, the second decade stage has an additional semiconductor switching element as well as an additional switch on, the magazine compartment (s) assigned to only the first decade is actuated and when it is actuated, the influence of the voltage series of the second decade stage is canceled at the output of the first comparison device. Is one of the top ten Slides in the ready position for projection, so is the additional semiconductor switching element as well as the additional switches of the second decade stage operated.

According to a further development, the series of voltages of the first and second DeJcadenstufe by a Resistance chain formed from ten equal resistors from the first decade and from Resistances of the second decade stage exist, the resistance value of which is ten times greater is than the resistance values of the first decade stage, with the taps between the resistors with the one output electrodes of the semiconductor switching elements are connected, while the other output electrodes the semiconductor switching elements are brought together in a decade and each connected to an input of a comparison device are.

According to another advantageous embodiment, the voltage series are the first and second decade stage formed from separate voltage divider stages, each semiconductor switching element a voltage divider is assigned. The voltage dividers expediently indicate for each decade a common resistance, which by means of the semiconductor switching elements is each a discrete Resistance can be switched on. Those facing the common resistance of the first stage of the decade Connections of the divider resistances are with the one input and those with the common contradiction of the Connections of the divider resistors facing the second decade to the second input of the first Comparison device connected.

The switches of the selection device are then advantageously provided with a separate resistance chain for the first and second decade, the voltage levels being those of the decade levels correspond.

Field effect transistors are particularly advantageous as semiconductor switching elements.

Appropriately, the switches of the selector are relay contacts, the relays of which are Option keys can be influenced.

Operational amplifiers are used as a comparison device according to a further training Gain factor by providing equal resistances in the input branches and irr ίο feedback branch is approximately equal to one.

According to a further embodiment, there are two transistor-controlled ones in the output circuit of the second operational amplifier Relay is provided through which the transport motor for the forward and backward transport of the magazine is controllable.

According to a further development, the resistance chain of the selection device is connected to the plus and minus poles connected to a voltage source. Furthermore, there is a potential on the selector switches of the first decade applied, which has the value zero compared to the plus and minus potential of the voltage source. In addition, the selector switches of the second decade are directly connected to the further input of the second Operational amplifier connected. The first input of the second operational amplifier, however, is mil connected to the output of the first operational amplifier. As a result, there is advantageously no Auxiliary comparison device required.

Furthermore, from the output of the second operational amplifier to the digital-to-analog converter is advantageous a feedback connection is provided through which the converter is on forward odei Down counting is adjustable.

To achieve bounce-free pulses, the pulse device has a switch through which a bistable multivibrator can be influenced. The changeover switch advantageously has three contact springs and two circular concentrically arranged on a disk, rotatable by the transport motor Contact tracks, one contact track via the one contact spring with a first input eini Tilting stage and its other contact path via the second contact spring with a second input dei Flip-flop is connected. The third Kontaktfedei stands alternately in the plane of the two contact tracks provided rectangular contact lugs of the first and second contact tracks in connection, so that when the contact disk is rotated, the third contact spring alternates between one and the other the other input of the flip-flop is connected to a fixed potential. The approaches of one contact path are offset from the approaches of the other contact track. Thus, it becomes a reliable allows bounce-free impulses, which has zui consequence that disturbances in the counting and transport process are largely avoided.

In the following, the invention is based on two, in F i g. 1 to 5 illustrated embodiments described. Show it

6c F i g. 1 to 3 a first embodiment and F i g. 4 and 5 a second embodiment. According to FIG. 1, 1 denotes a slide projector. A magazine 3, in which slides 4 can be found, is inserted into a magazine guide 2 of the slide projector 1. A screw ί is via a transport motor 5 a pinion 8 engaging in a Zahnleistc 7 can be driven. By the transport motor 5, the maeazin step by step for each magazine compartment optionally into one

or transported in another direction. By a controlled in a known manner shuttle spool 9 of the magazine 3, the slide located in the projection position of readiness Ax from the magazine compartment 3 χ in a Projektionsstcllung brought and 4 A reset after the projection of the slide 'in the magazine compartment at standstill.

According to FIGS. 1 and 1a, a disk 10 can be driven by the drive motor 5, the two circular ones Has contact tracks 11 and 12. These are arranged concentrically to the axis of rotation of the disk 10. Both contact tracks 11 and 12 each have at the same intervals 11a and 12a, which in the Level of the contact tracks 11 and 12 lie. The contact track 11 works with a contact spring 13, the contact track 12 with a contact spring 14 together, 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 IS is connected to the negative pole of a voltage source 17.

The drive motor 5 is 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 bus, from which a connection to the input of a gate Gl or Gl or G 3 or G 4 or G 5 or G 6 or G 7 or G 8 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 are the outputs of the bistable multivibrators 30 to 33 of the second digital stage with bus lines connected, each with an input of a four-input gate GOO or GlO or G20 or G30 or G40 ... or G90 are connected. From gates GOO to G 90 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 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 are arranged. As in the embodiments it is assumed that a maximum of 50 slides should be shown, are only those the magazine compartments or slides 10 to 40 counting gates G10 to G 40 of the second decade level activated. The GOO gate is assigned to the zero step of the second decade stage. This is effective when the macazin compartments or slides one to ten should be counted or demonstrated.

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

ίο 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

ao collector of transistor 43 a connection 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 brought together and connected to a connection point 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 collector 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 equal resistors 81, 82, 83, 84, 85, 86, 87, 88, 89 and 90 for the first decade stage on the keys Γ1, Γ 2, Γ 3, Γ 4, TS , T6, Tl, Γ8, Γ9 and TO are connected. The resistors 81 to 90 to opposite sides of the keys Tl Γ0 are brought together and connected to a connection point A1. Further resistors 91, 92, 93, 94 and 95 are connected in series with resistors 81 to 90. The resistors 91 to 94 are of the same size and have resistance values that are ten times greater than the resistance values of the individual resistors 81 to 90. The resistors 91 to 94 are assigned to the second decade stage. At these resistors are keys Γ00, ΓΙΟ, Γ20, Γ30, Γ40 The connected resistors 91 to 94 facing away from the key Seiter Γ00 to Γ 40 are merged unc connected to a connection point A third

The sinks (drains) of the field effect transistors 6 (to 75 are connected to the taps of the first deca The resistors 81 to 90 associated with the stage are connected. Also are the sinks of the field effect transi 76 to 80 interfere with the taps of the resistors 91 to 9i assigned to the second decade stage connected. On the one side of the chain of resistance consisting of resistors 81 to 9: Minus potential and zero potential on the other side.

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

609 616/3

to 80 via the connection point A 4 and via a resistor 101 to a first input of an operational amplifier 102 . The sources of the field effect transistors assigned to the first decade stage are connected to the second input of the operational amplifier 102 via the connection point A 2 and via a resistor 100 . A feedback resistor, which has the same size as the two resistors 101 and 100, is denoted by 103. The output of the operational amplifier 102 is connected to a first input of a second operational amplifier 105 via a resistor 104 . A feedback resistor, which has the same size as the resistor 104, is denoted by 106.

The keys 00 to Γ40 of the second decade stage are connected to the first input of an operational amplifier 97 via the connection point A 3 and a resistor 98 . The Tl keys until the first decade of Γ0 stage are connected via the connection point A 1 and via a resistor 96 to the second input of the operational amplifier 97th A feedback resistor is labeled 99. This has the same size as the resistors 96 and 98. The output of the operational amplifier 97 is connected to the second input of the second operational amplifier 105 via a resistor 107 . A common connection leads from the output of the second operational amplifier 105 to the bases of two transistors 108 and 109. In the collector circuit of the transistor 108 there is a relay

110 and a relay 111 is arranged in the collector circuit of the transistor 109. The relay 110 is connected to the positive pole of a voltage source 112 and the relay

111 connected to the minus pole of a further voltage source 113 . Both voltage sources 112 and 113 are connected in series. The emitters of the two transistors 108 and 109 are brought together and connected to a tap between the two voltage sources 112 and 113 . The switches 18, 19 and 20, 21 are assigned to the relay 110 and 111.

Furthermore, the output of the second operational amplifier 105 is connected via the connection point A 5 and via a diode 114 to the two digital stages 22 and 23 for the first and second decade. This feedback connection has the task of indicating to the digital-to-analog converter whether it should count up or down.

The way it works is now as follows:

It is assumed that the keys Π and Γ00 are actuated and that the first magazine compartment intended for these keys or the first slide is in a position ready for presentation. As a result, the field effect transistors 66 and 66 are turned on. Between the connection points .4 t and A 3 and between the connection points A 2 and A 4 there is a voltage which is determined by the voltage drop across the resistor 90 . Since the same voltage is now applied to the inputs of the second operational amplifier 105 , the voltage at its output is equal to zero, with the result that the two transistors 108 and 109 are blocked. As a result, the relays 110 and 111 are deenergized.

The changeover switch 18 can be operated through the relay 110 and the changeover switch 20, 21 through the relay 111

In the de-energized state of the two relays 110 and 111 , the changeover switches 18, 19 and 20, 21 are in the position shown in FIG. 1. As a result, the motor 5 is at a standstill.

Should z. If, for example, the 10th magazine compartment is brought into the ready position, the Γ0 key is pressed. The Γ00 key remains pressed while the Y L key is opened. As a result, the voltage between the connection points A 3 and A 1 increases by ίο nine voltage units to ten times the voltage value. The result is that the equilibrium in the second operational amplifier 105 is disturbed and the transistor 108 is permanently controlled for forward control. The relay 110 is energized and the contact 18 of the changeover switch 18, 19 is closed. The drive motor 5 receives voltage and rotates in the sense of a forward movement of the magazine 3. During the forward movement of the magazine 3, a pulse is sent to the bistable multivibrator 16 via the pulse disk 10 as the magazine 3 advances from one magazine to the next. The field effect transistors 67, 68, 69, 70, 71, 72, 73, 74 and 75 are now switched through one after the other. When a field effect transistor is activated, the field effect transistor previously activated is blocked, so that when the field effect transistors 66 to 74 are activated, the field effect transistors 66 to 74 are blocked. If the field effect transistor 75 is now through, the voltage at the two inputs of the second operational amplifier 105 is the same. As a result, the transistor 108 is blocked again and the relay 110 is de-energized. The transistor 109 was previously in the blocking state and consequently the relay 111 was de-energized. The drive motor 5 is stopped because the contacts 19 and 21 of the changeover switches 18, 19 and 20, 21 are closed.

The digital-to-analog converter had previously been notified via the connection points -1 5 and the diode 114 that it had to count in the forward direction. Should now be the 25th magazine compartment in Bercitschaftsstelhing! buttons Γ 20 and Γ5 are pressed. The voltage between the two inputs of the second operational amplifier 105 then has a value. which is equal to fifteen inches of tension. The relay 110 is again energized. and the contact 18 of the changeover switch 18. 19 closed. The result is that the motor 5 is set in rotation again in the sense of a forward movement of the magazine 3. Jc Magarinfach a pulse 7.11m bistable multivibrator 16 is emitted. The field effect transistor 7? locked at! the field effect transistor 77 of the second printing sleeve is cut off. With the second pulse, field effect transistor 66 will turn on. while the field effect transistor 77 remains turned on. Now the field-effect transistors 67 to 75 will be controlled. With the H. pulse the field effect transistor 77 is blocked and the field effect transistor 78 is durchgestcucvt. After the 15th pulse, the field effect transistors 70 and 78 are turned on, while all other field effect transistors are blocked. Since after fifteen pulses the voltages of the two inputs of the operational amplifier 105 are equal, the relay 110 is abcrrcgt and the motor 5 is stopped. If the 10th magazine compartment is now selected again by pressing the keys 700 and Γ0, the voltage at the second input of the operational amplifier 105 is reduced by fifteen voltage units. The result is.

that the transistor 109 is controlled to and the relay 111 is energized. The contact 20 of the changeover switch 20, 21 is closed and the motor 5 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 Tcilerabgriff is connected to the connection point A 2 '.

With the sources of the field effect transistors 76 'to 80' of the second decade stage are resistors 130, 131, 132, 133 and 134 connected. These resistors 130 to 134 form together with a common one Resistor 135 a voltage divider.

ίο The resistors 130 to 134 are chosen so that when the field effect transistors 76 'to 80' are switched through one after the other, the voltage at the divider tap changes by ten voltage units each time. 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' associated with the buttons TV to TO 'and 700' to Γ40 '

zo is designed in 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 resistance chain and a plus potential at the other end of the resistance chain. Another difference is that the connection point AV is not connected to the input of an operational amplifier. At the connection point A Γ, the potential is zero. The connection point A 3 'is connected directly to the second input of the second operational amplifier 105' via the resistor 107 '.

The operation of the second embodiment is the same as that of the first embodiment game.

For this purpose 4 sheets of drawings

Claims (14)

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 which generates a pulse for each magazine compartment or for each slide in the magazine that passes a fixed point during transport of the magazine with a control device comprising a selector for choosing a magazine compartment or a slide, a influenceable by the pulse device adjusting device, which compares a preset Wählgröße with a position determined by the actuator manipulated variable, wherein the control unit when the equality causes a shutdown of the magazine when the preselected magazine compartment or the preselected slide has reached a ready-to-projection position, characterized in that the adjusting 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) 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 one Semiconductor switching element (e.g. 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 each via a semiconductor switching element (z. B. 76) of the second decade stage (23, 25) a voltage value of an equal 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, at the further input of the first comparison device (102) that the output of the first comparing means (102) is connected to one input of a further comparing means (105), whose further input corresponding dial pad (Tl to 70 and TOO to Γ 40) with at least one of the series of the first and second decade, the target position of the magazine (3 ) defining voltage series can be connected, and that, depending on the selected magazine compartment, the semiconductor switching elements of the first and possibly the second decade stage are switched through one after the other until the servomotor (5) and the pulse device (10) are stopped when the voltages at the input of the further comparison device (105) are the same. 2. Slide projection device according to claim 1, characterized in that the second decade stage (25) has an additional semiconductor switching element (76) and an additional switch (7Ό0), which is / are actuated in the case of the magazine compartments assigned only to the first decade and in 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 resistance chain consisting of ten equal resistors (81 to! M)) of the first decade stage unc from a factor of ten larger, equal resistances (91 to 95) of the second decade that the taps between the resistances are connected to one of the output electrodes of the semiconductor switching elements (66 to 75 and 76 to 80], while the others Output electrodes of the semiconductor switching elements are brought together in a decade and are each connected to an input (A 2 to A4) 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 (Tl to. TO and 700 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 Singang (A 3) of the auxiliary comparison device (97). 5. Slide projection device according to claim 1 or 2, characterized in that the voltage series the first and second decade stage from separate voltage divider stages (120/129 to 129 and 130/135 to 134/135) are formed, each semiconductor switching element having a voltage divider assigned. 6. Slide projection device according to claim 5, characterized in that the voltage divider each decade have a common resistance (129 b7w. 135), which by means of the semiconductor switching elements 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 (Tl to TO and Γ00 to Γ 40) of the selection device with a separate resistor chain (81 'to 95') are connected for the first and second decade, wherein the voltage levels correspond to those of the voltage divider of the decade level. 9. Slide projection device according to one of the preceding claims, characterized in that that the semiconductor switching elements are field effect transistors. 10. Slide projection device according to one of the preceding claims, characterized in that that the switches of the selector are relay contacts, their relays through the selector buttons can be influenced. 11. Slide projection device according to one of the preceding claims, thereby cekenn- shows that the comparison devices are operational amplifiers, their gain factor by providing resistors (100, 101, 103) of equal size in the input branches and in the Feedback branch is approximately equal to one. 12. Slide projection device according to one of the preceding claims, characterized in that that in the output circuit of the second operational amplifier (105) two transistor-controlled transport is in a separate circuit from the control circuit Circuit arranged through the contact of a control relay, through the contact of a drive for the slide change process and influenced by the contact of the relay for changing the direction of rotation will. An electromagnetic zero indicator circuit, the two relays, serves as a comparison device and their contacts. A tracking switch is controlled by the magazine movement, whereby (108, 109) relays (110, 111) are provided, io a gear is necessary that through each magazine the transport motor (5) for the advance, the further switching of a rotary switch by one step. A relay receives the in interaction with drive-dependent switches by closing the control circuit The zero indicator circuit has resistor chains that must be dimensioned so that the through the Indicator relay current flowing is always equal to or greater than the pick-up current of the relay. As a result and return transport of the magazine (3) is controllable. 13. Slide projection device according to one of claims 5 to 12, characterized in that the resistance chain of the dialer on the 15 resolved selection process is maintained to completion. The plus and minus pole of a voltage source is connected so that the selector switch (ΓΓ to
7Ό ') of the first decade a potential is applied
is that opposite the plus and minus potential the voltage source has the value zero and 20 the individual resistances of the resistor chains that the selector switches (Γ00 'to Γ40') of the second are not made arbitrarily large. Also can Decade directly with the further input of not any number of resistors provided, second operational amplifier (105 ') connected as at least the pull-in current of the relay in one are, during the first input of the operation case and in the other case a by the number of Amplifier (105 ') with the output of the first 25 resistors increased current flow through the relay Operational amplifier (102 ') is connected. 14. Slide projection device according to one of the preceding claims, characterized vog g shows that from the output of the second opera- (05) diil