The chassis is even awesome like many others. It' s very solid and well organized.
Power supply is above, Line deflection + EHT is contained in the left box in the cabinet, all receiver functions are in the main PCB.
The tuning circuits has a large knob potentiometers tuning system which use voltage controlled capacitances such as varactor diodes as the frequency determining elements.
Therefore a stable AFC circuit is developed:
A superheterodyne receiver having an automatic intermediate frequency control circuit with means to prevent the faulty regulation thereof. The receiver has means for receiving a radio frequency signal and mixing the same with the output of a superheterodyne oscillator. This produces an intermediate frequency signal which is coupled to a frequency or phase discriminator to produce an error signal for controlling the frequency of the superheterodyne oscillator. A regulation circuit is provided having an electronic switch to interrupt the feedback circuit when only unwanted frequencies tend to produce faulty regulation of the superheterodyne oscillator.
Power
Supply: The examples chosen are taken from manufacturers' circuit
diagrams and are usually simplified to emphasise the fundamental nature
of the circuit. For each example the particular transistor properties
that are exploited to achieve the desired performance are made clear. As
a rough and ready classification the circuits are arranged in order of
frequency: this part is devoted to circuits used at zero frequency,
field frequency and audio frequencies. Series Regulator Circuit Portable
television receivers are designed to operate from batteries (usually
12V car batteries) and from the a.c. mains. The receiver usually has an
11V supply line, and circuitry is required to ensure that the supply
line is at this voltage whether the power source is a battery or the
mains. The supply line also needs to have good regulation, i.e. a low
output resistance, to ensure that the voltage remains constant in spite
of variations in the mean current taken by some of the stages in the
receiver. Fig. 1 shows a typical circuit of the power -supply
arrangements. The mains transformer and bridge rectifier are designed to
deliver about 16V. The battery can be assumed to give just over 12V.
Both feed the regulator circuit Trl, Tr2, Tr3, which gives an 11V output
and can be regarded as a three -stage direct -coupled amplifier. The
first stage Tr 1 is required to give an output current proportional to
the difference between two voltages, one being a constant voltage
derived from the voltage reference diode D I (which is biased via R3
from the stabilised supply). The second voltage is obtained from a
preset potential divider connected across the output of the unit, and is
therefore a sample of the output voltage. In effect therefore Tr 1
compares the output voltage of the unit with a fixed voltage and gives
an output current proportional to the difference between them. Clearly a
field-effect transistor could do this, but the low input resistance of a
bipolar transistor is no disadvantage and it can give a current output
many times that of a field-effect transistor and is generally preferred
therefore. The output current of the first stage is amplified by the two
subsequent stages and then becomes the output current of the unit.
Clearly therefore Tr2 and Tr3 should be current amplifiers and they
normally take the form of emitter followers or common emitter stages
(which have the same current gain). By adjusting the preset control we
can alter the fraction of the output voltage' applied to the first stage
and can thus set the output voltage of the unit at any desired value
within a certain range. By making assumptions about the current gain of
the transistors we can calculate the degree of regulation obtainable.
For example, suppose the gain of Tr2 and Tr3 in cascade is 1,000, and
that the current output demanded from the unit changes by 0.1A (for
example due to the disconnection of part of the load). The corresponding
change in Tr l's collector current is 0.1mA and, if the standing
collector current of Tr 1 is 1mA, then its mutual conductance is
approximately 4OmA/V and the base voltage must change by 2.5mV to bring
about the required change in collector current. If the preset potential
divider feeds one half of the output voltage to Tr l's base, then the
change in output voltage must be 5mV. Thus an 0.1A change in output
current brings about only 5mV change in output voltage: this represents
an output resistance of only 0.0552.Power supply is realized with mains transformer and Linear transistorized power supply stabilizer, A DC power supply apparatus includes a rectifier circuit which rectifies an input commercial AC voltage. The rectifier output voltage is smoothed in a smoothing capacitor. Voltage stabilization is provided in the stabilizing circuits by the use of Zener diode circuits to provide biasing to control the collector-emitter paths of respective transistors.A linear regulator circuit according to an embodiment of the present invention has an input node receiving an unregulated voltage and an output node providing a regulated voltage. The linear regulator circuit includes a voltage regulator, a bias circuit, and a current control device.
The bias circuit may include a bias device and a current source. The bias device has a first terminal coupled to the output terminal of the voltage regulator and a second terminal coupled to the control electrode of the current control device. The current source has an input coupled to the first current electrode of the current control device and an output coupled to the second terminal of the bias device. A capacitor may be coupled between the first and second terminals of the bias device.
In the bias device and current source embodiment, the bias device may be implemented as a Zener diode, one or more diodes coupled in series, at least one light emitting diode, or any other bias device which develops sufficient voltage while receiving current from the current source. The current source may be implemented with a PNP BJT having its collector electrode coupled to the second terminal of the bias device, at least one first resistor having a first end coupled to the emitter electrode of the PNP BJT and a second end, a Zener diode and a second resistor. The Zener diode has an anode coupled to the base electrode of the PNP BJT and a cathode coupled to the second end of the first resistor. The second resistor has a first end coupled to the anode of the Zener diode and a second end coupled to the reference terminal of the voltage regulator. A second Zener diode may be included having an anode coupled to the cathode of the first Zener diode and a cathode coupled to the first current electrode of the current control device.
A circuit is disclosed for improving operation of a linear regulator, having an input terminal, an output terminal, and a reference terminal. The circuit includes an input node, a transistor, a bias circuit, and first and second capacitors. The transistor has a first current electrode coupled to the input node, a second current electrode for coupling to the input terminal of the linear regulator, and a control electrode. The bias circuit has a first terminal for coupling to the output terminal of the linear regulator and a second terminal coupled to the control electrode of the transistor. The first capacitor is for coupling between the input and reference terminals of the linear regulator, and the second capacitor is for coupling between the output and reference terminals of the linear regulator. The bias circuit develops a voltage sufficient to drive the control terminal of the transistor and to operate the linear regulator. The bias circuit may be a battery, a bias device and a current source, a floating power supply, a charge pump, or any combination thereof. The transistor may be implemented as a BJT or FET or any other suitable current controlled device.
TAA611-A12 - Dual BTL power audio amplifier
TCA 511 TV HORIZONTAL AND VERTICAL PROCESSOR
The TCA 511 is a silicon monolithic integrated circuit in a 16—lead dual in—line plasticpackage. It incorporates the following functions: high stability horizontal oscillator,
horizontal APC circuit with high noise immunity and large pull—in range, high stability
vertical oscillator and sawtooth generator.
lt is intended for driving TV horizontal and vertical transistorized output stages.
APPLICATION INFORMATION
Power Supply
The circuit can work with stabilized supply voltage having a value from 9 to 15 V.
A dropping resistor and a filter capacitor may be used to obtain the suipply from higher
voltages; however, the voltage on pins 3 and 4 must never exceed the maximum
permitted voltage.
Synchronization
Pins 2 and 6 can be DC driven if the reference level of the synchronization pulses is
less than 1 V. With reference levels greater than this value, a coupling capacitor must
be inserted in series with the input, and pins 2
and 6 must be connected to ground
via a resistor.
Vertical Oscillator
The capacitor connected to pin 1 must be selected with regard to the frequency
tolerance, to the thermal stability and to the capacitor's ageing.
The width of the output pulse, to be chosen according to the needs of the output
stages, is defined by the resistor connected between pin 1 and pin 16.
Vertical Output
The vertical output is taken from pin 14, which is a buffered output of the sawtooth
voltage generated at pin 15.
The output current from pin 14 is defined by an internal resistor in the integrated
circuit. if a greater current is needed, a resistor may be connected between pin 14
and pin 3.
The oscillator output pulse is available at pin 15 if the capacitor C9 is not connected. _
This configuration is used for driving output stages in which the sawtooth is generated
by Miller effect.
Horizontal Oscillator
The capacitor connected between pin 10 and ground must be selected with regard
to the frequency tolerance, 1:0 the thermal stability and to the capacit0r’s ageing.
In multistandard receivers, the oscillation frequency may be changed by switching the
value of the capacitor connected to pin 10.
TBA 311 TV SIGNAL PROCESSING CIRCUIT
The TBA 311 is a monolithic integrated circuit in a 16-lead clual in-line or quad in—Iine
plastic package. It is intended for use as signal processing circuit for black and
white and colour television sets.
The circuit is designed for receivers equipped with tubes or transistors in the deflection
and video output stages, and with PNP or NPN transistors in the tuner and NPN in
the IF amplifier.
Only signals with the negative modulation can be handled by the circuit. The circuit
is protected against short circuit between video output and GND. The TBA 311 includes:
0 VIDEO PREAMPLIFIER with EIMITTER FOLLOWER OUTPUT
0 GATED AGC for VIDEO» IF AMPLIFIER and TUNER
0 NOISE INVERTER CIRCUIT for GATING AGC and SYNC. PULSE SEPARATOR
o HORIZONTAL SYNC. PIULSE SEPARATOR
0 VERTICAL SYNC. PULSE SEPARATOR
0 BLANKING FACILITY for the VIDEO AMPLIFIER.
CRT TUBE is a FIVRE 12 B 121
The TUBE CRT TUBE FIVRE 12 B 121 is fabricated by an extint Italian manufacturer.
It's a 120° degree type so it's very compact.
FIVRE WAS Fabbrica Italiana Valvole Radio Elettriche which was fabricating Picture tubes and Radio Tubes.
FIVRE were established in 1932 as a manufacturer of thermoinic valves.
Cathode ray tubes for monochrome television sets were introduced in 1952.Since then, many millions of FIVRE CRTs have been incorporated in TV sets by most European brand leaders.
In 1976 FIVRE extendet the product rance to include monochrome data display tubes, gaining in a short time a large share of the European market.
The FIVRE range of CRT are used in applications demanding a quality product, in both the civil and military areas, including: high-resolution graphics and desk-top-publishing, radar, large screen dispays and medical equipment; to name but a few.
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