Ivory sheets :
Le poste Decretet CF2
by Camel Belhacene.
Life of the club :
Assemblée générale ordinaire Radiofil Sarcey 13 avril 2019
by Michel Cretteur.
Restauration d'un poste ARVIN 444
by Pierre Rouaud.
I bought this little American wireless at a car boot sale for eight Euros. It’s a four valve (12SA7, 12SQ7, 50L6, 35Z5) AC/ DC superheterodyne which runs on 117 V.
Un amplificateur audio de puissance moyenne
by Daniel Maignan.
(push-pull de 6L6 avec transfo RTU101)
A few years ago, Jean Revidon (RFL-106) sent the Radiofil editor a valve amplifier project based on one he had aleady covered in Radiofil magazine #59.
The purpose was to guide the experienced amateur who wished to build a low frequency amplifier, with a circuit that has the originality of being able to offer several operating configurations with the same assembly ; that’s why it is deemed as experimental.
But this amplifier was only a project and it seemed difficult to present it to our readers without building at least one mock-up to subject to tests and measurements as is normal with such equipment.
I therefore decided to undertake its construction. For this I asked Andre Dos Santos (RFL-5236), of the ‘Bassin d’Arcachon’ radio club, to make up an aluminium chassis then install the valve bases and a tag board, as well as the various connectors, the transformer, etc. and finally to wire it all up.
The hybrid stabilised power supply has electronic filtering, which means ripple can be reduced to almost zero without using the ever-present filter choke. Finally, it must be pointed out that only a single device is covered here and that obviously a second must be built if a stereo system is required.
Le retour de la réaction
by Daniel Maignan.
Here is the description of a modest regenerative receiver which is both easy and fun to make.
What could be simpler than this little semiconductor assembly powered by a 9V battery and using only three transistors.
Moreover it seems to give better reception, less bothered by parasitics, than most of the transistor radios from my collection which I tried out for comparison.
It is true that a good aerial is required in order for it to function correctly.
In the course of Web :
Au fil du forum
by Serge Logez.
Un transformateur d’alimentation comme transformateur de sortie ?
As most of you know, the Radiofil forum, which is open to all vintage radio and audio enthusiasts, is a hub of good natured discussion and exchange and therefore an invaluable source of information, with regular participation from other countries. We select subjects which we believe will be of great interest to our readers and publish them in the magazine, with particular consideration for those who don’t have Internet. The question asked in this edition is as follows :
Can a mains transformer with 115 / 220 V primary and 6,3 V secondary be used as an output transformer for a push-pull amplifier? Do the laminations have to be modified and what would be the drawbacks of such an arrangement?
Introductory courses :
Initiation aux transistors
by Gérard Prieur.
At the time of integrated circuits, multilayer printed circuits with metallized holes and CMS (Surface Mount Components), it may seem obsolete to be interested in the discrete active components that are the bipolar transistors. We will, however, be interested in them and see how to use them around simple basic circuits.
Rebobinage d'un transformateur toroïdal
by Alain Fargeix.
We have seen in Radiofil magazine #83 how to calculate and carry out the rewinding of a power transformer with a “classic” magnetic circuit, that is with either EI or C-Core configuration. This time, we are going to explore the rewinding of a toroidal power transformer in an application that will be much easier to achieve
Les téléphones de campagne
by Alain Levasseur.
Il was more than likely that the army would be interested in this new mean of transmission invented by Graham Bell, the telephone. As early as 1886, that’s ten years after its invention, the army experimented with a device developed by Colson (Figure 1). This one draws heavily on Bell’s initial system, with magnetic microphone serially connected with a pair of headphones.