The television tuning system employs a frequency synthesizer system for establishing the tuning of the receiver, featured with a Microcomputer driven synthesis system, coupled to a frequency lock controller chip such as a Philips TSA5511 / SIEMENS SDA3202. This tuner can tune television signals on VHF and UHF band. Recently, frequency synthesizers including a phase locked loop (PLL) have been suggested to accurately generate local oscillator signals at predetermined frequencies corresponding to the various channels which a viewer may select.
The system employed in the tv permits utilization of a frequency synthesizer tuning system which correctly tunes to a desired television station or channel even if the transmitted signals from that station are not precisely maintained at the proper frequencies even in combination of a fine tuning adjustable by the user.To enable operation of the receiver in a fringe area, where it may be desirable to intentionally mistune a channel slightly, manual fine tuning control logic circuitry is employed to disable the frequency offset logic circuit and to permit changing the count of the reversible counter by the viewer to manually fine tune the receiver as desired.
Accordingly, it is an object of this invention to provide an improved tuning system for a television receiver.
It is an additional object of this invention to provide an improved frequency synthesizer tuning system for a television receiver.
Headphone jack is present frontly.
Rear side the AV SCAR socket is present.
This was an all day easy tellye unexpensive and durable with great pictures.
The set here shown like other Mivar tv's was introducing a novelty in power supply design;Switch-mode power supply with burst mode standby operation:
In a typical switch mode power supply (SMPS) of a television receiver the AC mains supply voltage is coupled to a bridge rectifier. An unregulated direct current (DC) input supply voltage is produced. A pulse width modulator controls the duty cycle of a chopper transistor switch that applies the unregulated supply voltage across a primary winding of a flyback transformer. A flyback voltage at a frequency that is determined by the modulator is developed at a secondary winding of the transformer and is rectified to produce DC output supply voltages such as a voltage B+ that energizes a horizontal deflection circuit of the television receiver and a voltage that energizes a remote control unit.
During normal operation, the DC output supply voltages are regulated by the pulse width modulator in a negative feedback manner. During standby operation, the SMPS is required to generate the DC output supply voltage that energizes the remote control unit. However, most other stages of the television receiver are inoperative and do not draw supply currents. Consequently, the average value of the duty cycle of the chopper transistor may have to be substantially lower during standby than during normal operation.
Because of, for example, storage time limitation in the chopper transistor, it may not be possible to reduce the length of the conduction interval in a given cycle below a minimum level. Thus, in order to maintain the average value of the duty cycle low, it may be desirable to operate the chopper transistor in an intermittent or burst mode, during standby. During standby, a long dead time interval occurs between consecutively occurring burst mode operation intervals. Only during the burst mode operation interval switching operation occurs in the chopper transistor. The result is that each of the conduction intervals is of a sufficient length.
In accordance with an aspect of the invention, burst mode operation intervals are initiated and occur at a rate that is determined by a repetitive signal at the frequency of the AC mains supply voltage. For example, when the mains supply voltage is at 50 Hz, each burst mode operation interval, when switching cycles occur, may last 5 milliseconds and the dead time interval when no switching cycles occur, may last during the remainder portion or 15 milliseconds. Such arrangement that is triggered by a signal at the frequency of the mains supply voltage simplifies the design of the SMPS.
The burst mode operation intervals that occur in standby operation are synchronized to the 50 Hz signal. During each such interval, pulses of current are produced in transformers and inductances of the SMPS. The pulses of current occur in clusters that are repetitive at 50 Hz. The pulses of current occur at a frequency that is equal to the switching frequency of the chopper transistor within each burst mode operation interval. Such qurrent pulses might produce an objectionable sound during power-off or standby operation. The objectionable sound might be produced due to possible parasitic mechanical vibrations as a result of the pulse currents in, for example, the inductances and transformers of the SMPS.
In accordance with another aspect of the invention, the change in the AC mains supply voltage during each period causes the length of the conduction interval in consecutively occurring switching cycle during the burst mode operation interval to increase progressively. Such operation that occurs during each burst mode operation interval may be referred to as soft start operation. The soft start operation causes, for example, gradual charging of capacitors in the SMPS. Consequently, the parasitic mechanical vibrations are substantially reduced. Also, the frequency of the switching cycles within each burst mode operation interval is maintained above the audible range for further reducing the level of such audible noise during standby operation.
A switch mode power supply, embodying an aspect of the invention, for generating an output supply voltage during both a standby-mode of operation and during a run-mode of operation includes a source of AC mains input supply voltage. A control signal at a given frequency is generated. A switching arrangement energized by the input supply voltage and responsive to the first control signal produces a switching current during both the standby-mode of operation and the run-mode operation. The output supply voltage is generated from the switching current. An arrangement coupled to the switching arrangement and responsive to a standby-mode/run-mode control signal and to a signal at a frequency that is determined by a frequency of the AC mains input supply voltage controls the switching arrangement in a burst mode manner during the standby-mode of operation. During a burst interval, a plurality of switching cycles are performed and during an alternating dead time interval no switching cycles are performed. The two intervals alternate at a frequency that is determined by the frequency of the AC mains input supply voltage.
These set were offering excellent bright and crisp pictures and very good sound for a very fair price.
Furthermore they were very robust and easy to fix.
It's made by MIVAR an Italian Brand no more active since 20/12/2013.
MIVAR is a Factory site in the near of Milan (italy) in a Industrial city conglomerate called Abbiate Grasso.
1945 - Milan, Via Ugo Tommei 5: Begin the activity assembling small radios.
1950 - Via Curtatone 12: developed with the construction of more direct major radio components fabricants.
1956 - 13 Street Strigelli: industrial production is manily targeted to first radio devices with frequency modulation (FM).
1958 - Via P. 30 Jordanians: TV become a reality, the industries is doubling his ACTIVITY, always in Milan, we build the first "real" plant with 400 employees.
1963 - Abbiategrasso, Via Dante 45: in the wake of decentralization and the rampant success of the television, building a facility that will become important in place 800 employees occupying between 1968-70.
1990 - Abbiategrasso Canal towpath: aware of the physiological importance that television plays in society? Modern, rich expertise and resources, we began construction of a factory area of 120,000 m? which covered 30.00o , for the viabilit with parking spaces and 60,000 park trees.
Today's activity is oriented in virtual production of LCD crap but with very low market penetration due to "unfair" asian competitors presence and a local governement which don't care about.
(You call it global market, I call it WORLD DESTRUCTION combined toghether with mass Afro scum crap Immigration (EUROPEAN INVASION) to obtain destruction on a large scale in all places and to help more and better the loose of all OUR workplaces and firms , lives, people).
“If our buildings, our highways, and our railroads should be wrecked, we could rebuild them.
If our cities should be destroyed, out of the very ruins we could erect newer and greater ones.
Even if our armed might should be crushed, we could rear sons who would redeem our power.
Anyway Obsolete Technology Tellye will show even this model as a Time machine which looses nothing of the good tellyes ! ! !
Further Notes:
MonrifNet, Televisori Mivar: fine dei programmi il 30 novembre - Il Giorno - Legnano, su www.ilgiorno.it. URL consultato l'11 gennaio 2018.
^ “La mia Mivar chiude, l’affitto gratis a chi assume 1200 italiani”, in Fanpage. URL consultato l'11 gennaio 2018.
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