Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and information about some of the electronic, electrical and electrotechnical technology relics that the Frank Sharp Private museum has accumulated over the years .

Premise: There are lots of vintage electrical and electronic items that have not survived well or even completely disappeared and forgotten.

Or are not being collected nowadays in proportion to their significance or prevalence in their heyday, this is bad and the main part of the death land. The heavy, ugly sarcophagus; models with few endearing qualities, devices that have some over-riding disadvantage to ownership such as heavy weight,toxicity or inflated value when dismantled, tend to be under-represented by all but the most comprehensive collections and museums. They get relegated to the bottom of the wants list, derided as 'more trouble than they are worth', or just forgotten entirely. As a result, I started to notice gaps in the current representation of the history of electronic and electrical technology to the interested member of the public.


Following this idea around a bit, convinced me that a collection of the peculiar alone could not hope to survive on its own merits, but a museum that gave equal display space to the popular and the unpopular, would bring things to the attention of the average person that he has previously passed by or been shielded from. It's a matter of culture. From this, the Obsolete Technology Tellye Web Museum concept developed and all my other things too. It's an open platform for all electrical Electronic TV technology to have its few, but NOT last, moments of fame in a working, hand-on environment. We'll never own Colossus or Faraday's first transformer, but I can show things that you can't see at the Science Museum, and let you play with things that the Smithsonian can't allow people to touch, because my remit is different.

There was a society once that was the polar opposite of our disposable, junk society. A whole nation was built on the idea of placing quality before quantity in all things. The goal was not “more and newer,” but “better and higher" .This attitude was reflected not only in the manufacturing of material goods, but also in the realms of art and architecture, as well as in the social fabric of everyday life. The goal was for each new cohort of children to stand on a higher level than the preceding cohort: they were to be healthier, stronger, more intelligent, and more vibrant in every way.

The society that prioritized human, social and material quality is a Winner. Truly, it is the high point of all Western civilization. Consequently, its defeat meant the defeat of civilization itself.

Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

OLD, but ORIGINAL, Well made, Funny, Not remotely controlled............. and not Made in CHINA.

How to use the site:

- If you landed here via any Search Engine, you will get what you searched for and you can search more using the search this blog feature provided by Google. You can visit more posts scrolling the left blog archive of all posts of the month/year,
or you can click on the main photo-page to start from the main page. Doing so it starts from the most recent post to the older post simple clicking on the Older Post button on the bottom of each page after reading , post after post.

You can even visit all posts, time to time, when reaching the bottom end of each page and click on the Older Post button.

- If you arrived here at the main page via bookmark you can visit all the site scrolling the left blog archive of all posts of the month/year pointing were you want , or more simple You can even visit all blog posts, from newer to older, clicking at the end of each bottom page on the Older Post button.
So you can see all the blog/site content surfing all pages in it.

- The search this blog feature provided by Google is a real search engine. If you're pointing particular things it will search IT for you; or you can place a brand name in the search query at your choice and visit all results page by page. It's useful since the content of the site is very large.

Note that if you don't find what you searched for, try it after a period of time; the site is a never ending job !

Every CRT Television saved let revive knowledge, thoughts, moments of the past life which will never return again.........

Many contemporary "televisions" (more correctly named as displays) would not have this level of staying power, many would ware out or require major services within just five years or less and of course, there is that perennial bug bear of planned obsolescence where components are deliberately designed to fail and, or manufactured with limited edition specificities..... and without considering........picture......sound........quality........

..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

Have big FUN ! !
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©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All sets and apparates appearing here are property of
Engineer Frank Sharp. NOTHING HERE IS FOR SALE !

Friday, February 4, 2011

GRUNDIG T818/16 CHASSIS 29300-467.01.31 INTERNAL VIEW













































































































This GRUNDIG CHASSIS 29300-467.01.31 is directly power supplyed by mains via a series power stabiliser and parallel resistor type.
A series regulator (dropper type power supply) is known as a power supply unit that changes an input direct current (DC) voltage input from a DC power supply into a stabilized output DC voltage.
This series regulator changes the input DC voltage to the stabilized output DC voltage that is lower than the input DC voltage.
This series regulator, however, converts a power loss generated by voltage drop between an input and an output of a semiconductor device such as a transistor, used as a three-terminal regulator device serving as a main controlling device, into heat. Thus, in a case where the voltage drop is large, the power loss in the semiconductor device also becomes large, thereby reducing the reliability of the entire product.
The present invention relates to a power supply unit. More particularly, the present invention relates to a power supply unit with a series regulator (dropper type power supply).
Therefore, it is an object of the present invention to provide a power supply unit, which is capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to the first aspect of the present invention, a power supply unit having a series regulator that changes an input DC voltage input from a DC power supply into a stabilized output DC voltage lower than the input DC voltage, comprises: a power consuming unit, provided on a direct current path between the DC power supply and an input side of the series regulator, including a parallel circuit formed by a first fixed resistor and a semiconductor device having a current input, a current output and a setting input; and a current setting unit operable to set an amount of a current flowing between the current input and the current output of the semiconductor device, wherein the current input of semiconductor device is arranged on a DC-power-supply side thereof, the current output of the semiconductor device is arranged on a series-regulator side thereof, and the setting input of the semiconductor device is connected to a setting output of the current setting unit.
According to the second aspect of the present invention, a power supply unit having a series regulator that changes an input DC voltage input from a DC power supply into a stabilized output DC voltage lower than the input DC voltage, comprises: a first power consuming unit, provided in parallel to the series regulator, including a parallel circuit formed by a first fixed resistor and a first semiconductor device having a current input, a current output and a setting input; and a first current setting unit operable to set an amount of a current flowing between the current input and the current output of the first semiconductor device, wherein the current input of the first semiconductor device is arranged on a series-regulator-input side thereof, the current output of the first semiconductor device is arranged on a series-regulator-output side thereof, and the setting input of the first semiconductor device is connected to a setting output of the first current setting unit.
Electronic parts and instruments are operated by DC powers and it is necessary to feed the DC power with a stable voltage level for the stable operation of such instruments and parts with high reliability.An adjustable DC power supply regulated by the combination of a voltage dropping resistor in series between the DC source and the load, a transistor shunting the load, and other transistor circuitry that monitors the load voltage while drawing very little current, and responds to any load voltage change to adjust the bias on the shunt transistor in a direction to change the current drawn by the shunt transistor and thereby to change the voltage drop across the voltage dropping resistor to oppose change in load voltage.In such a system the series regulators must be kept in the linear mode, i.e. they must always have at least a minimum impedance so that they can perform the regulatory function. Even if the minimum impedance could theoretically be reasonably small, it is generally considerably larger so as to ensure that regulation can occur under extreme conditions. Inasmuch as the impedance is generally resistive, the efficiency of the supply is reduced because of power dissipation occurring therein.
The other conventional power supply employs a transformer whose primary is connected to an AC power line and whose secondary is coupled to a rectifier section to produce a direct voltage output. The output level of the supply may be adjusted in various ways as by controlling the transformer primary voltage or turns ratio, or secondary voltage, by variable autotransformers, by tap switches, by the use of saturable reactors, and by other well-known expedients. Once the desired DC output voltage is established, it may be necessary to hold it constant in spite of line voltage or load changes. Most power supplies, therefore, require some kind of regulator to maintain a constant DC output.In this arrangement, if series regulator circuits are used, a greater heat radiation fin or a cooling device is required because voltage variation of a DC power source is applied to the regulator circuits to increase the heat developed at transistors in the circuits. Therefor a parallel shunt resitor is placed across the output  regulator transitor.Regulation is generally effected by a DC feedback signal produced by transducing a voltage or current component in the output circuit, the feedback signal being applied to a regulator element to vary the input of the supply in a manner maintaining a constant output.In one type of conventional power supplies, the main pass transistor is generally connected to a voltage regulator source within the power supply so that the transistor is continuously operative in regulating the output of the supply to a fixed voltage for fluctuations in load and line current. The input of the main pass transistor is connected to a DC rectifier generally consisting of a plurality of diodes which deliver a DC output voltage to the transistor slightly higher than the voltage rating of the output of the supply. The main pass transistor is generally connected to a large heat sink which is capable of assisting the transistor in dissipating large amounts of power due to the voltage drop between the input and output of the pass transistor and the load current passing therethrough. The power capability of conventional power supplies is best limited to the maximum power dissipation which the transistor and suitable heat sink are capable of handling for any given situation. For small regulated power supplies capable of providing a few watts of DC power to the output, it is possible to utilize a single main pass transistor and heat sink combination without difficulty. However, for a large power requirement it is often necessary to utilize multiple transistors and large heat sinks in order to provide for the large power dissipation which takes place under full load conditions. This greatly increases not only the size of the power supply, but also its cost since additional components are required in order to handle the increased load.

The chassis is mainly based on discretes and ICs.

- TDA3190P (MOTOROLA) TDA3190 TV SOUND CHANNEL (sgs)


The TDA3190 is a monolithic integrated circuit in a

16-lead dual in-line plastic package. It performs all

the functions needed for the TV sound channel :


.IF LIMITER AMPLIFIER .ACTIVE LOW-PASS FILTER

.FM DETECTOR

.DC VOLUMECONTROL

.AF PREAMPLIFIER .AF OUTPUT STAGE


DESCRIPTION

The TDA3190 can give an output power of 4.2 W
(d = 10 %) into a 16 W load at VS = 24 V, or 1.5 W
(d = 10 %) into an 8 W load at VS = 12 V. This performance, togetherwith the FM-IF section characteristics

of high sensitivity, highAM rejection and low distortion, enables the device to be used in almost every type of television receivers.

The device has no irradiation problems, hence no external screening is needed.

The TDA3190 is a pin to pin replacement of TDA1190Z.


The electrical characteristics of the TDA3190 remain almost constant over the frequencyrange 4.5

to 6 MHz, therefore it can be used in all television standards (FM mod.). The TDA3190 has a high
input impedance,so it can work with a ceramic filter or with a tuned circuit that provide the necessary
input selectivity.
The value of the resistors connected to pin 9,determine the AC gain of the audio frequency amplifier.

This enables the desired gain to be selected in relation to the frequency deviation at which the

output stage of the AF amplifier, must enter into clipping.

Capacitor C8, connected between pins 10 and 11, determines the upper cutoff frequency of the audio

bandwidth.To increase the bandwidth the values of C8 and C7 must be reduced, keeping the ratio

C7/C8 as shown.

The capacitor connected between pin 16 and ground, together with the internal resistor of 10 KW

forms the de-emphasis network. The Boucherot cell eliminates the high frequency oscillations

caused by the inductiveload and thewires connecting the loudspeaker.

- TDA3653 (PHILIPS)TDA3653B
TDA3653C
Vertical deflection and guard circuit
(90˚)

GENERAL DESCRIPTION
The TDA3653B/C is a vertical deflection output circuit for drive of various deflection systems with currents up to
1.5 A peak-to-peak.
Features
• Driver
• Output stage
• Thermal protection and output stage protection
• Flyback generator
• Voltage stabilizer
• Guard circuit
FUNCTIONAL DESCRIPTION
Output stage and protection circuit
Pin 5 is the output pin. The supply for the output stage is fed to pin 6 and the output stage ground is connected to pin 4.
The output transistors of the class-B output stage can each deliver 0.75 A maximum.
The maximum voltage for pin 5 and 6 is 60 V.
The output power transistors are protected such that their operation remains within the SOAR area. This is achieved by
the co-operation of the thermal protection circuit, the current-voltage detector, the short-circuit protection and the special
measures in the internal circuit layout.
Driver and switching circuit
Pin 1 is the input for the driver of the output stage. The signal at pin 1 is also applied via external resistors to pin 3 which
is the input of a switching circuit. When the flyback starts, this switching circuit rapidly turns off the lower output stage
and so limits the turn-off dissipation. It also allows a quick start of the flyback generator.
External connection of pin 1 to pin 3 allows for applications in which the pins are driven separately.
Flyback generator
During scan the capacitor connected between pins 6 and 8 is charged to a level which is dependent on the value of the resistor at pin 8.
When the flyback starts and the voltage at the output pin (pin 5) exceeds the supply voltage, the flyback generator is activated.
The supply voltage is then connected in series, via pin 8, with the voltage across the capacitor during the flyback period.
This implies that during scan the supply voltage can be reduced to the required scan voltage plus saturation voltage of the output transistors.
The amplitude of the flyback voltage can be chosen by changing the value of the external resistor at pin 8.
It should be noted that the application is chosen such that the lowest voltage at pin 8 is > 2.5 V, during normal operation.
Guard circuit
When there is no deflection current and the flyback generator is not activated, the voltage at pin 8 reduces to less than 1.8 V. The guard circuit will then produce a DC voltage at pin 7, which can be used to blank the picture tube and thus prevent screen damage.
Voltage stabilizer
The internal voltage stabilizer provides a stabilized supply of 6 V to drive the output stage, which prevents the drive
current of the output stage being affected by supply voltage variations.


- BUY71 (TOSHIBA)

BUY71 Transistor Datasheet. Parameters and Characteristics.

Type Designator: BUY71

Material of transistor: Si

Polarity: npn

Maximum collector power dissipation (Pc): 40W

Maximum collector-base voltage (Ucb): 2200V

Maximum collector-emitter voltage (Uce):

Maximum emitter-base voltage (Ueb): -

Maximum collector current (Ic max): 10A

Maximum junction temperature (Tj): 200°C

Transition frequency (ft): -

Collector capacitance (Cc), Pf: -

Forward current transfer ratio (hFE), min/max: 8MIN

Manufacturer of BUY71 transistor: TI

Package of BUY71 transistor: TO3

Application: Power, High Voltage, General Purpose


The tuner is based on TUA2000 Osc + Mix + TBA120T

It's very compact and serviceable because it's based on the development Ideas related to CUC70KT which you can see HERE , but it shares only the layout basis and nothing more.

The current flowing through the horizontal deflection coil of a cathod ray tube is controlled by a transistor which is switched between saturation and cut off by a circuit having a pulse generator for generating a pulse in response to a horizontal synchronizing pulse.
In many cathode ray tube monitors as well as television receivers the horizontal magnetic deflection of the electron beam is provided by a "resonant recovery" circuit wherein a transistor is switched to control the current flow through the circuit to establish the retrace and sweep intervals of each line scan. In order to minimize power dissipation in the transistor, it operates as a saturated switch which is cut off to start the retrace interval that is immediately and automatically followed by the sweep interval. However, cut off of the transistor does not immediately follow the application of a cut off controlling signal derived from the conventional horizontal synchronizing signal. There is a delay resulting from the inherent storage time of the transistor. This storage time is among other things dependent on the degree and length of time the transistor was in saturation. Thus, it should be apparent that the start of each sweep interval is a function of the storage time of the transistor.








GRUNDIG  T818/16  CHASSIS  29300-467.01.31 MECHANIC KEYBOARD BUTTONS OVERVIEW. GRUNDIG Tuning unit with bandswitch for high frequency receivers:


Abstract:

A tuning unit with a bandswich for high frequency receivers having a potentiometer system for the control of capacity diodes is disclosed. The potentiometer system includes a plurality of parallelly disposed resistance paths on which wipers can be moved by means of screw tuning spindles mounted beside one another in a common housing made of an insulating material. The bandswitch is formed of metal wires and is associated with each tuning spindle. The tuning spindles are joined for rotation with sleeves simultaneously forming the operating knobs which are carried in apertures in the front plate and each have a flange engaging the back side of the front plate about the apertures. The flange is slightly larger than the cross section of the apertures and tapers conically away from the back side of the front plate.




1. Tuning unit with bandswitch for high frequency receivers having potentiometer means for the control of capacity diodes composed of a plurality of parallelly disposed resistance paths on which wipers are moved by means of screw tuning spindle means mounted beside one another in a common housing of insulating material, bandswitch means formed of metal wires associated with each tuning spindle means, said tuning spindle means being joined for rotation with sleeve means simultaneously forming operating knobs which are borne in apertures in the front plate and each sleeve means having an axial flange surface engaging the back side of the front plate about one aperture therein, said flange surface being slightly larger than the cross section of the apertures and tapering conically away from the back side of the front plate.


2. Tuning unit of claim 1 wherein the sleeve means are joined telescopically and coaxially with the tuning spindle means, and the flange surface engages the back side of the front plate when the sleeve means are in the state wherein they are pulled out of the front plate.


3. Tuning unit of claim 1 wherein the ends of the tuning spindle means which are opposite the front plate have each an annular groove into which a spring bracket engages whose bent end is supported against the housing and which has two diametrically disposed spring arms having opposite spring curvature, the said spring arms in each case contacting the opposite axial walls of the groove.


4. Tuning unit of claim 3 wherein the spring bracket rests with its bent end against the housing and the spring arms additionally engage a bracket formed on the housing or an intermediate bracket formed in one piece with the connection soldering lugs.


5. Tuning unit of claim 3 wherein the spring bracket is formed in one piece with the connection soldering lugs and has spring arms curved both in the same direction which engage an axial wall of the annular groove in the spindle and the opposite axial wall rests against a housing wall.


6. Tuning unit of claim 1 wherein the pointers associated with each potentiometer means lie on the one hand in windows associated with each tuning spindle means in the front plate, and on the other hand are rotatably mounted with their ends opposite the front plate in pivot pins on the housing, and the guiding pin of the spindle nuts carried in a longitudinally displaceable manner on each tuning spindle is provided with a slit disposed parallel to the longitudinal axis of the tuning spindle and slides with its peripheral surface resiliently within the slide tract of the pointer.


7. Tuning unit of claim 1 wherein the bandswitches are formed each of a displaceable metal rod which is in working engagement with stationary metal rods common to all bandswitches of a tuning unit, contacting each of them individually.


8. Tuning unit of claim 7 wherein the metal rods are metal wires.


9. Tuning unit of claim 7 wherein the metal rods are stamped metal parts.


10. Tuning unit of claim 7 wherein levers of insulating material are placed on the front ends of the displaceable metal rods and extend through windows which are provided with detents and which are associated with each tuning spindle in the housing front plate, while the opposite ends are held fixedly in the rearward end of the housing, and the displaceable metal rods individually make contact with contact cams on the stationary metal rods, these cams being in an offset array corresponding to the detents in the windows, the corresponding rods extending parallel to the front plate and parallel to one another behind the front plate.


11. Tuning unit of claim 7 wherein insulating material bridges or insulating material slide pieces are inserted between the contact cams of two adjacent, stationary metal rods and within the free space between two such parallel metal rods.


12. Tuning unit of claim 7 wherein the displaceable metal rods have, in the vicinity of their mountings on the housing, an articulation in the form of a vertically disposed flat portion.


Description:

BACKGROUND

The invention relates to a tuning unit with bandswitch for high frequency receivers, especially radio and television receivers, having a potentiometer system for the control of capacity diodes, the said potentiometer system consisting of a plurality of parallel resistance paths along which wiper contacts can be driven by means of screw spindles disposed adjacent one another in a common insulating material housing in which a bandswitch formed of metal rods is associated with each tuning spindle.

In these tuning units, the working voltages of the capacity diodes in the tuning circuits are recorded once a precise tuning to the desired frequency has been performed. A potentiometer tuning system has great advantages over the formerly used channel selectors operating with mechanically adjustable capacitors (tuning condensers) or mechanically adjustable inductances (variometers), mainly because it is not required to have such great precision in its tuning mechanism.

Tuning units with bandswitches formed of variable resistances and combined with interlocking pushbuttons controlling the supply of recorded working voltages to capacity diodes are known. Channel selection is accomplished by depressing the knobs, and the tuning or fine tuning are performed by turning the knobs. The resistances serving as voltage dividers in these tuning units are combined into a component unit such that they are in the form of a ladderlike pattern on a common insulating plate forming the cover of the housing in which the tuning spindles and wiper contacts corresponding to the variable resistances are housed. The number of resistances corresponds to the number of channels or frequencies which are to be recorded. The wiper contact picks up a voltage which, when applied to the capacity diodes determines their capacitance and hence the frequency of the corresponding oscillating circuit. The adjustment of the wipers is performed by turning the tuning spindle coupled to the tuning knob. By the depression of a button the electrical connection between a contact rod and a tuning spindle is brought about and thus the selected voltage is applied to the capacity diodes. Since the push buttons release one another, it is possible simply by depressing another button to tune to a different receiving frequency or a different channel, as the case may be.

To permit the switching of a number of channels in a certain tuning range, bandswitches for a plurality of tuning ranges, such as UHF and VHF for example, are often provided in the tuning units described above. In the pushbutton tuning unit of the above-named type, the bandswitch consists of a printed circuit board which is fastened on the housing of the tuning unit, and a switch lever which is preset by means of the pushbutton by turning, and is operated by depressing the pushbutton while at the same time selecting the channel.

Where this combination of knobs and pushbuttons is not possible, the selection of the range is accomplished by means of an additional lever which can be set over to select the range.

However, since such tuning units require too many riveting operations when they are assembled, tuning units were later created in which the individual parts in the voltage divider and pushbutton housing were loosely inserted and/or held in place by projections, lugs, hooks or tabs of resilient plastic. In spite of these initial improvements, the bandswitch, especially the one associated with the tuning units, was still technically intricate and very expensive.

THE INVENTION

It is the object of the invention, therefore, to create an additionally improved and simplified tuning unit containing a bandswitch of simple, space-saving and reliably operating design.

In accordance with the invention, this object is accomplished in a tuning unit with bandswitch of the kind described in the beginning by joining the tuning spindles for rotation with sleeves simultaneously forming the control knobs, which are mounted in apertures in the front plate of the housing and have each a flange engaging the back of the front plate around the aperture, the said flange being slightly larger than the aperture and tapering conically away from the back of the front plate.

In further development, the sleeves can be joined telescopically for rotation with the tuning spindles, and the flange is able to engage the back side of the front plate when the sleeve is in the position in which it is drawn out of the front plate. The sleeves constructed in this manner, whose portions projecting from the apertures in the front plate form the control knobs for the tuning spindles, permit easy assembly of the tuning uni

t and at the same time assure positive co-rotation of sleeves and spindles. The sleeves can be pushed from the front side of the front plate through the apertures onto the clutch surfaces of the spindles, this inward pushing being easily accomplished on account of the taper, and the dropping out of the sleeve being prevented by the flange engaging the back of the front plate. If the control knobs project only slightly out of the front plate, they can be operated from the outside by inserting a tool into them. With the telescoping type of coupling, however, it is possible to draw the sleeves or control knobs further outwardly so that they can be rotated by hand without the use of tools.

To provide constant assurance of the axial fixation of the tuning spindles, the tuning spindle ends farthest from the front plate can each be provided with an annular groove engaged by a spring bracket whose one leg is supported against the housing and whose other leg is forked to form two spring arms, each bent in the opposite direction and each engaging one of the two opposite walls of the annular groove. The tuning spindles are secured against axial displacement by this construction of the invention alone, without the need for further measures. This facilitates the joining of the sleeves or control knobs to the tuning spindle, because in this case there is no need for precise axial fixation and extreme dimensional accuracy.

Furthermore, the indicators associated with each potentiometer can be mounted in windows in the front plate which are associated with each tuning spindle or tuning knob for visual indication at the front, the other extremities farthest from the front plate being mounted for pivoting on pins set in the housing; the guiding pin on the spindle nut that is driven longitudinally on each tuning spindle can be provided with a slit disposed parallel to the long axis of the tuning spindles and can slide within the indicator slide lever slot, with its surface resiliently engaging the walls of said slot.

In an especially advantageous embodiment, the tuning unit can have bandswitches each formed of a displaceable metal rod which is in contacting engagement individually with stationary metal rods which are common to all of the bandswitches of a tuning unit. It contrast to the bandswitches known hitherto, which as a rule consist of a printed circuit board with switchable contacts thereon, this frequency bandswitch of the invention is of great simplicity, can be manufactured simply and inexpensively, and at the same time is very reliable in operation.

The displaceable and stationary metal rods of the bandswitches can be formed of metal wires or they can be of stamped sheet metal. Also, in further expansion of the concept of the invention, the stationary metal rods thus formed can be all entirely alike and merely offset from one another, thereby further simplifying the manufacture and stocking thereof.

To permit connection also to audiovisual apparatus, one or more of the stationary metal rods can be divided electrically into at least two parts each.

In a special development of this concept, lugs of insulating material can be mounted on the front ends of the displaceable metal wires, these lugs extending through windows in the front plate of the housing which are associated with each tuning spindle and are provided with detents, while the opposite ends can be held fixedly at the rear end of the housing, and the displaceable metal wires can make contact with contact humps on the stationary metal wires, the humps being offset from one another to correspond to the detents in the windows, and the stationary metal wires extending in back of the front plate, parallel to the latter and parallel to one another.

To increase switching reliability, bridges or sliding pieces made of insulating material can be inserted between the contact humps of adjacent stationary wires within the free space between two such parallel lying metal wires.

To achieve easy displacement of the displaceable metal wires despite the fixed end mounting on the housing, the displaceable metal wires, in further embodiment of the invention, can have each an articulation adjacent their end mountings, in the form of a vertically disposed flattened portion. This flat permits the metal wires to be deflected horizontally against a weak spring bias.

DESCRIPTION OF THE DRAWING

As an example of the embodiment of the invention, there is represented in the drawings a tuning unit with bandswitch for television receivers. In these drawings,

FIG. 1 is a front elevational view of a tuning unit with bandswitch,

FIG. 2 is a plan view showing the bandswitch of the tuning unit of FIG. 1,

FIG. 3 is a side elevational, cross-sectional view of the tuning unit of FIG. 1,

FIG. 4 is a rear elevational view of the tuning unit of FIG. 1,

FIG. 5 is a plan view showing the indicator means of the tuning unit of FIG. 1,

FIG. 6 shows the sleeve with the operating knob and tuning spindle,

FIG. 7 shows the telescoping manner in which the sleeve is joined to the tuning spindle,

FIG. 8 is a fragmentary view of the bandswitch,

FIG. 9 is another fragmentary view of the bandswitch, and

FIG. 10 shows how the tuning spindle is fixed in position.

DESCRIPTION
The method of representation used in the drawings is greatly simplified, for the purpose of better delineating the features of the invention. The tuning unit with bandswitch consists of an insulating material housing 1 with a front plate 2, which is closed by a cover plate 3 accommodating the resistance paths. The housing 1 is divided by parallel sidewalls 4 into chambers in which the tuning spindles 5 are disposed.
The embodiments is an 8-fold tuning unit having eight bandswitches assocated with each tuning spindle, and eight indicators.
Accordingly, there are eight apertures 6 in a central row, through which the operating knobs 7 of the sleeves 8 coupled with the tuning spindles 5 are passed. The operating knobs 7 have recessed surfaces 9 for turning with a turning tool. In a row extending parallel above the row of the apertures 6 there are eight windows 10, whose upper edge is provided with notches 11. Lugs 12 of insulating material extend through the windows 10 and engage the upper notches 11 and are joined behind the front plate to displaceable metal wires 13 of the bandswitch. In a row located beneath the row of apertures 6 another eight windows 14 are provided, through which the ends of the pointers of the indicators 15 protrude.
Now, the bandswitch consists in each case of a displaceable metal wire 13 which can be brought into working engagement with stationary metal wires 16, which are all of the same construction and are only disposed offset from one another. While the displaceable metal wire 13 extends substantially parallel to the longitudinal axis and thus at right angles to the front plate 2, the stationary, parallelly disposed metal wires 16 are parallel to the front plate 2 and are thus inserted at a right angle to the displaceable metal wire. A departure from parallelism or from the right angle, as the case may be, takes place substantially only when the displaceable metal wire 13 is deflected to the two outer notches. The rearward end 18 of the displaceable metal wire, which forms a vertical loop, is tightly inserted into a receiver 17. Just ahead of the loop 18, the metal wire 13 is provided with a vertically disposed portion 19 by a flattening on the metal wire 13. The movement, when the metal wire 13 is deflected into the desired notches or detents, takes place horizontally by the flexing of these portions 19. The stationary metal wires 16 are held tightly in their positions in projections 20 on the housing, or by lugs or the like. Since three switch actions are provided, that is, three ranges, for each tuning spindle, a bandswitch consists of one displaceable metal wire and three stationary metal wires 16, which are used for all switches.
To permit each bandswitch to have exactly three switching actions, each of the three stationary metal wires 16 has one contact hump 21 corresponding to one of the detents 11 in the windows 10 of the front plate 2. The contact humps 21 are thus located one next to the other as seen from the front plate 2. So that the displaceable metal wire 13 will always come into mechanical and electrical contact only with the desired contact hump, and prevent short circuits, insulating bridges 22 are installed between the adjacent metal wires 16, said insulating bridges being stationary.
If more or less than three switching actions are desired, all that need be done in the case of the bandswitch of the invention is to change the number of stationary metal rods or wires accordingly.
The sleeves 8 with the operating knob 7 have a flange 23 engaging the back of the front plate 2 and tapering back to the point where it joins the tuning spindle. This enables the sleeves to be pushed in, in the case of a housing that has already been manufactured with the tuning spindle installed, without creating the possibility that the sleeves 8 might escape after they have been inserted. The sleeves 8 are connected to the tuning spindles 5 usually by means of driving surfaces. If manual operation without tools is to be possible, rather than requiring a tool for the operation of the sleeves, the coupling of the sleeve 8 to the tuning spindle will be a telescoping coupling (see FIG. 7).
The actual firm axial fixation of the tuning spindle 5 is located on the rear end of the housing. Here the tuning spindle 5 has an annular groove 24 which is engaged by a spring by means of two diametrically disposed spring arms 25 and 26. The spring arms 25 and 26 have oppositely curved lugs and are supported on the housing at their terminal and marginal surfaces and their lugs engage opposite axial walls 27 and 28 of the annular groove 24.
Additional support is provided by the common, bent foot 29 of the spring arms 25 and 26 against the cover plate of the housing.
The indicator means of the tuning unit with bandswitch consists of a pointer 15 which is movable within the window 14, and a cam 30 which is a prolongation of the pointer 15. At its rearward end, the pointer is mounted rotatably in the housing on pin 31. Within the cam 30 slides a guiding pin 32 which is attached to the spindle nut or carriage 40. Upon the rotation of the tuning spindle, the spindle nut is longitudinally displaceable therewith. In order to achieve good guidance and hence precise indication, the guiding pin has a slit 33 extending parallel to the longitudinal axis of the tuning spindle 5, so that it will resiliently engage the cam 30 within the slot thereof.
The necessary soldering lugs are indicated at 34.
On the basis of the design of the tuning unit with bandswitch in accordance with the invention, a desired frequency range--UHF, for example--can be selected by deflecting a displaceable metal wire 13 into one of the detents 11 by means of the lug 12 mounted thereon. Within this range, a transmitter or channel can then be selected by turning the tuning spindle 5. The transmitter preselected in this manner can then be tuned in by means of a keyboard or by electronic recall from a keyboard which is not shown. The fine tuning of this tuned-in transmitter, as well as the selection of a different transmitter within the same frequency range, is accomplished by turning the tuning spindle 5.
All of the details explained in the above description and represented in the drawings are important to the invention.







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