I believe that, as is tha case for i.e Philips, we could add a Swedish Oltronix with the history and add information to the dutch too. Many of the listed models should probably be linked to the Swedish company instead, definitely the ones marked Carl Olsson.

With the history I got I can also more precisely date the LS15.

The 'inside' contact Leif Pihlblad lives since 40 years or so in Meinisberg, Switzerland. .

Brief history (to be posted at the manufacturer):

The origins of Oltronix is a company "Carl Olsson" founded by Carl Olof Olsson in 1950-51.

The first employee was hired in 1952. The addres at this time was Långseleringen 95, Vällingby (10km west of Stockholm), Sweden which was also Carl O Olssons home address at this time.

1955 the companmy moved to Ångermannagatan 122, Vällingby in 1955 and the name was changed to Oltronix AB about 1958. This would make the production year of the LS15 I used to have to 1955-58.

Later 1955 Carl O Olsson moved to Atlanta, Georgia, USA, to work at Lockheed, which he did until late 1957 after that he put his focus back on Oltronix and also created Oltronix Inc in Georgia (data sheeets with this name exists from september 1959).

1960 Carl O Olsson moved back to Sweden and continued to expand Oltronix. New office at Jämtlandsgatan 125, Vällingby 1961-62 and in 1964 a subidiary was created in Holland. Manufacturing was also stated in Torsby, Sweden in the mid 60's which was expanded in 1969. Development and manufacturing in Switzerland and Germany from 1970. Oltronix delivered a large number of power supplies to Cern, Geneva, in the 1970's. Sales offices and agents in several European countries. 

The manufactoring in Torsby was 1974-77 concentrated for deliveries to Datasaab, Sweden (bank systems most likely), a business that was cancelled in 1977 whereafter the Torsby business was taken over by employees under the name Tepro.AB for some years. At this time all production had been moved outside Sweden, mainly Holland. 

Carl O Olsson moved to Switzerland during the 1970's and was also engaged in private avionics.

About 2003 the business in Holland was sold off including the brand name. Carl O Olsson died in 2009.leaving the Swiss business long-time emplyee (1962) Leif Pihlblad who should close it (and helped me with the information).

So, what does this make Oltronix? A Swedish or Dutch company,

Interesting (insider) story, thank you Anders.

Because you have chosen the red questionmark, it needs an answer within 6 days, otherwise it does not stick to the manufacturer.

Therefore I would say Sweden is the origin and a lot of brain work was probably there.
If we have models for a company in the USA we could create that US company and link them together.
So we can do for products which were made in other countries for those countries.
Any other idea?