10 Jahre
















One may raise the question: why does this file make sense to us?

The reason is quite pragmatic, because, in those days - Germany companies, not having their own valve-rectifier industry, tended, like did C. Lorenz A.G. to use semi-conductor rectifiers (for HT applications). Whilst, in contrast, Telefunken and Philips relied heavily upon valve rectifiers. This, of course, is only a general fact, and not true in all circumstances. On the other hand, the GEMA company, not having a real (own) valve production, relied, generally, on valve rectifiers.


Semi-conductor rectifiers (Se) were rather popular in Germany. Their downside - the forward-conducting-resistance Rg (Ri) did increase during operation. The system was therefore provided with transformer taps as to increase the supply voltage; by this means compensating, eventually, for a decreasing voltage. I cannot instantly remember having once seen that the tap was set at the highest voltage-tap possible. In my perception indicating, that it is quite likely that in wartime practice there was no direct need for it. 

Additionally, from very long experience I know, that on the long term it becomes quite stable. Of course, we do not operate historical equipment 7 x 24, and my experience is only valid for, say, some hundred hours annually but, for more than fours decades.   


Particularly the photos are of interest, because they show apparatus specifications, as well as what these look like. Some of which are rather impressive, as long as we do not compare them with modern switched-power-supply systems.

Maybe not well known, is the coming into being of S.A.F.

Following the content of the genuine text:

.... Tatsächlich aber sind nicht mehr als zehn Jahre vergangen, seitdem der Selen-Trocken-Gleichrichter erstmals fabrikatorisch in kleinen Mengen hergestellt wurde. Seine Geburtsstätte war die Apparatefabrik der Süddeutschen Telefon-Apparate, Kabel- und Drahtwerke A.G. (TE KA DE) in Nürnberg, aus der die Süddeutsche Apparte-Fabrik G.m.b.H., als S.A.F. mit dem Begriff Selen-Trocken-Gleichrichter untrennbar verbunden, im Jahre 1930 als selbständiges Unternehmen hervorgegangen ist. *

* Trocken means: dry. Liquid rectifiers goes back to the early years of the 20th Century. In those early days, there existed also chemical (liquid) rectifiers. Maybe, trocken was, also, used as to distinguish between semi-conductor and valve rectifiers. 

A few pages further down, they recall the specifications from where it did start, and what the current (1938) state of achievement is.

Um aber den Fortschritt der Entwicklung deutlich vor Augen zu führen, sollen doch einige Zahlen seiner ursprünglichen und der heutigen Strom- und Spannungsbelastbarkeit vergleichsweise gegenübergestellt werden:




10 Jahre Selen Trockengleichrichter   

Click at the above link, and open it integrally in PDF


At least the editor of this brochure understood well the wide ranging implication, of taking notice of what once have been published. Following his genuine wording:

Kurz nur, ohne langatmige Angaben von zeitlichen und technischen Daten. Denn - wenn dieses Heft früher oder später auch der Vergangenheit anheimfällt, so soll es vorher doch gelesen werden. Vielleicht sogar mit einigem Interesse. Das ist der Wunsch, den wir ihm mit auf den Weg geben.

What we do, might never have been envisioned by the editor, that we take notice of the same content as was once published in 1938. The world has changed much since, he could never have foreseen the implications of the internet; and that his brochure is accessible, after 77 years, world-wide.




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