Hi guys
I have some Osram lamps with the very old date code. One letter and two numbers. for Example h39. Does anybody have a list for this kind of codes?


Best regards Alex

I would also like to know how this works but don't have any reliable information, and Osram seems not to have records going this far back.

So in such cases I think we are going to have to figure it out ourselves, and to do that it's helpful to have details of the largest possible quantity of lamps with this kind of marking.  Perhaps then a pattern would become obvious.  I have made below a list of all my lamps having this kind of structure, and some others appearing on LG:

a27  James Incandescent approx. 1930s
e13  James Incandescent approx. 1940s
c39  James Barretter approx 1940s
d36  James Barretter approx 1940s
h39  Alex's lamp
h33  James Mercury approx. 1940-50
m24  Rigo HgH 10000 approx 1940s
n38  Rigo HgHS 1000 approx 1940s
p30  James Mercury approx. 1940-50
z13  James Mercury approx. 1940-50
z22  James Mercury approx. 1940-50
z32  James Mercury approx. 1940-50

Based on this we can conclude that the first digit is always a letter and it is always lower case
The second digit is always a number and possibly only a 1, 2, or 3
The third digit is always a number and presumably runs from 0 to 9

My best guess so far is that the letter indicates the year, and is perhaps simply a backwards repetition of the year letters that Osram used from 1953-1973, and partially repeated from 1974-1994.  The combination of the numbers perhaps reveals the month and/or quarter, possibly also the factory but I don't have a clear idea of how.

If anyone else has old Osram lamps with this code, please add them to the list and perhaps we could then decipher the structure more accurately!

Hello James
I have these codes with correct date:
m12: April 51
e19: November 51
h39 1937
regards

Did they use the same codes regardless of the lamp type ?

I have spent quite some time building a list of all the lamps appearing on this site as well as the German, Polish and Russian lighting forums whose members have quite a large selection of Osram lamps with this date code.

After putting it all into a database and sorting things by lamp type, estimated date and factory, a clear pattern has emerged.  This has led me to develop a theory for the structure of this code which appears to fit at least these lamps I am aware of.  For anyone interested, you can see at the following link: http://www.lamptech.co.uk/Documents/Codes/Date%20Codes%20-%20Osram%20German%20pre-1953.pdf

I would be very grateful if others here could check the accuracy of this against their lamps with this kind of code and report on whether or not this delivers a logical combination of date and factory.

That's really a great job, James, and thank for sharing such valuable analysis (I'm surprised of the lack of response and gratitude here...). I haven't dug into this old Osram code as much as you did, but your overall conclusions coincide roughly with mine. Here's what I have written in my archives in the past year about this particular code:

The code consists of a small letter followed by two numbers. Inferred from various pre-1953 Osram lamps, the letter includes (among other) a, c, d, e, f, g, h, m, n, p, z, and most certainly refers to the production quarter, grouped by four for each factory in the way used in the post-1953 code. The first number is only 1, 2, or 3 and most certainly refers to the first, second, and third month of a given quarter. The first letter and number thus provide the exact production month and factory. Finally, the last number goes from 0 to 9 and most likely refers to the production year in a 10-year cycle. It is possible that the letter and first number combination points towards a specific decade. For instance, a group of four letters cater for the 1930s, replaced by another group of letters for the 1940s, and another one for the 1950s. It is also found that the first number cannot refer to the decade, so its multiple of three must nevertheless be used with four letters to describe the exact production month.

For the correspondence between letter groups and factory I re-used most of the post-1953 coding system as a guide, but you did a much more thorough investigation. All in all, I think your analysis is very good and I'll update my own notes to account for your findings!

Thanks Max!  There is much more valuable feedback on the German lighting forum.

There are also quite a few other early Osram date codes we still have to crack - for instance the 1910s/20s with roman numerals quite similar to Philips at that time, and also three-letter codes which do not end in the already known R,S,T,U,V,W,X,Y,Z.  Plus a few other early Radium codes that are still a mystery.

I've made an Excel overview with the codes from all of my Osram lamps, plus others that are pictured online.  If anyone else has an interest to work on these please let me know!  Often it is only possible to work out these codes when a large number of lamps can be studied, to start looking for patterns in which letters and numbers are used in which positions in the code, and to try and correlate that with the estimated production date and the most likely production sites.  My own collection of early Osram lamps is quite limited, so it would be of great value to consider the examples of other collectors.