This company is relatively little-known and specialised in semiconductor diodes. I am grateful to Gert in Germany for providing most of this information and links to relevant sources. ECO must have been established in mid 1958 or earlier, as evidenced by the appearance of advertisements in the German electronics magazine 'Funkshau' in May and June 1958, one of which is shown on the right. At this time the company name is 'Eberle & Co. Elektro GmbH' and they are advertising silicon diodes, rectifiers, and Zeners. However, no part numbers are given.
Fortunately Gert has sent me a scan of their 1964 'Halbleiter Datenbuch' part 2, which contains their 03 series of what they call 'gleichrichterzellen' or 'rectifier cells', namely low-power silicon diodes. The company is now called 'Eberle Köhler & Co Elektronik KG'.
Information from a former, now retired ECO employee indicates that at some time around the mid 1960s ECO was split into two parts, whereby the semiconductor division became part of InterControl (current name 'INTER CONTROL Hermann Köhler Elektrik GmbH & Co. KG'). From then on, the component names began with 'NT' (supposedly an abbreviation of the renamed semiconductor division 'Nortron') instead of the former 'ECO'; the numbers as well as the specs remained unchanged, though.
The 1964 data book desribes three groups of diodes:
- 0320, 0321, 0322, 0324, 0327 1.25A rectifiers for reverse voltages 50V, 100V, 200V, 400V, 700V with 0.1µA leakage
- 0310, 0311, 0312, 0314, 0317 the same as the above but with 10µA leakage current. The image shows 0310.
- 0300, 0301, 0302, 0304, 0307 the same as the above but 1µA leakage current
I do not have contemporary data (or any at all!) for their power rectifiers or Zener diodes. If you know where I might obtain some, please