GELOSO GTV 8F170 YEAR 1969.

The GELOSO  GTV 8F170 is A portable 19 inches B/W television screen with rotary channels selectors for VHF and UHF tuning.

(Television set kindly donated to me by Marshal Elia Z.)


The B/W Tubes Television set was powered with a External Voltage stabiliser unit (portable metal box) which relates to voltage regulators of the type employed to supply alternating current and a constant voltage to a load circuit from a source in which the line voltage varies. Such regulators are frequently provided employing saturable core reactors and condensers connected in circuit...  in such manner as to provide a plurality of variable voltage vectors which vary in different senses, as the line voltage varies, but which add vectorially in such manner that their vector sum remains substantially constant upon variations in line voltage, for providing automatic voltage stabilization of single or multiphase A. C. circuits where the supply voltage and frequency are subject to variation above and below normal value and where the load is subject to variation between normal limits.
voltage stabilization
is automatically effected by the provision of an inductive pilot control device which is adapted to provide two excitation supply voltages for producing excitation or satuation of two magnetic circuits of a reversible booster transformer unit or units and diversion of flux from one magnetic circuit to the other, the booster unit being energized by primary windings from the A. C. supplysystem and being provided with a secondary winding or windings connected between the supply system and the corresponding inain or distribution circuit and in series therewith, through which a corrective boost voltage is
imrorjiiced into the circuit under the influence of the pilot control device, of an amount equal to that of the supply voltage fluctuation which initiated it and appropriate in polarity and direction for restoring the voltage to normal value and providing automatic stabilization of the circuit voltage against supply voltages which fluctuate above and below normal value.

The pilot control device which may be employed singly or may comprise three units or their equivalent when applied to multiphase supply systems comprises a pair of closed magnetic circuits or cores constructed of strip wound magnetic material or stacked laminations, the two
circuits forming a pair being constructed of materials possessing dis~similar magnetic characteristics when jointly energized by identical windings in series or by a collective primary winding, the said magnetic circuits being suitably proportioned to provide equal fluxes when ener-
gized at normal voltage.

The pilot control device is provided with a main and an auxiliary secondary winding or group of windings, the main secondary winding or windings being adapted to provide a voltage representing the difference in the fluxes of the two circuits to which it is jointly associated, while
the auxiliary secondary winding embraces only one circuit, preferably that subject to the least amount of flux variation. Either of the windings consists of two equal sections or in effect a double winding with a center tapping to which one end of the single winding is connected.

The voltage in the single secondary winding of the pilot device becomes directionally additive to that in one half of the tapped secondary winding and substractive in respect to that in the other half. When the supply voltage is normal the voltage provided by the single secondary winding is zero, since there is no difference of flux in the two magnetic circuits, and the two excitation voltages
produced in the halves of the other secondary winding are equal and when connected to the two excitation windings of the booster units, do not produce any diversion of flux between the two circuits or sets of circuits in the magnetic system of the booster transformer unit become equal, and since the series winding on the booster unit is arranged to provide a voltage due to the difference of
the fluxes in its two magnetic circuits or sets of magnetic circuits, no corrective voltage is introduced into the main circuit by the booster. If, however, the supply voltage varies from normal the pilot control device provides a voltage across the one secondary winding due to the difference in the fluxes of the two dis-similar magnetic circuits of which it is comprised, which voltage is combined with thosc in the halves of the other secondary winding to provide two excitation voltages which vary complementarily to each other as the supply voltage fluotuates, and cause a transference of flux between the two
circuits or groups of circuits in the booster unit and automatically provide a corrective boost voltage in the main circuit in which the series winding of the booster transformer is includcd of a value equal to that of the variation in supply voltage which initiated it.
The pilot device may be arranged in various ways, forboth single phase and multiphase operation, as exemplified by the constructions hereinafter more fully described.Similarly, numerous arrangements of the booster transformer unit are possible, some of which are hereinafter described in detail. The booster transformer unit embodies thc principles of the inductive devices described in my co-pending Application No. 411,189, filed February 18, 1954.

As an alternative to the provision of an auxiliary secondary winding on the pilot control device this may be
replaced by an independent or external source of supply,which may be either subject to or independent of supply voltage variation, provided such supply may be arranged with a center tapping if required.

Feed-back arrangements may be employed for providing compensation against voltage drop due to the effects of load in various ways. These are preferably providedon the booster transformer unit and may comprise a current transformer in one or more lines of the main circuit,
the secondary output of the transformer being rectified and arranged to energize an additional excitation winding on the booster transformer unit which in clfect increases the amount of the corrective boost voltage as the load increases.






Geloso, founded in 1931 by John Geloso, was an Italian manufacturer of radios, televisions, amplifiers, amateur receivers, audio equipment and component electronics, that had headquarters in Milan, Viale Brenta 29.
In 1931 they began to produce not only Radio but also, by choice of John Geloso same, most of the electronic components with which they were built, and over time developing and patenting also many others.
After the Second World War, Geloso expanded and expanded his production, becoming from 1950 onwards a real point of reference for domestic electronics enthusiasts and hobbyists.
The many products under the brand name Geloso were known throughout Italy and much appreciated abroad. It was innovative products, high quality, well-made and the low price. The big production was formed of radio, amplifiers, tape recorders, televisions, boxes of assembly, professional laboratory instruments etc. but also components such as capacitors, resistors, potentiometers, switches, connectors, transformer, microphones, etc.

Geloso was considered a good businessman, but also strongly wanted to share his passion for electronic. He created in 1932 Technical Bulletin GELOSO, a free quarterly publication that not only contained everything needed for the repair and development of its equipment, but also and above all, updates, tips, instructions, characteristics, schemes and everything that technicians and enthusiasts of had to know.
Those were the years in which there were no training centres and schools electronics were extremely rare.
These bulletins had the merit of spreading, so simple and clear, the knowledge to people who otherwise would not have any way to learn and develop their passion.

Another important contribution of Geloso were mounting kits. The kits allowed for TVs and radios to be home-assembled almost from scratch, beginning with raw metal frames onto which components were installed. There was also a user-friendlier line of pre-assembled, pre-calibrated kits and, also available, were cabinets, knobs, keys, etc. - all branded Geloso. Bulletins instructed how to calibrate finished units.
By 1969 - the year John Geloso died - S.p.A. Geloso had become an empire of eight manufacturing facilities. Production persisted till 1972, when the business closed. Several were the reasons for the end of activities: fierce foreign competition, managerial problems, union demands and massive indebtedness to banks.
Some of S.p.A. Geloso most successful products were: radio receivers, tape recorders, audio amplifiers, record players, television sets, radio and TV parts, ham receivers and transmitters.