Probably used for telephone devices or similar, seems to be a MP metal paper design, from 1936? It is rated at 650V and has a 0.25uF capacity (still, just tested). I have not found out who the manufacturer is - is there a logo database somewhere to hunt it down?
Have a few and want to get rid of them as I have no need for these.
DANKE! That's EXACTLY what I was desperately looking for, never he4ard of this company. These caps were most likely installed in German prewar or war telephones, I found them next to oodles of mic and headset capsules in the basement, wher my Dad had stashed awy several old bakelite phones, still in boxes.
Thanks for all the interesting inputs about this odd device and long- gone company, never heard of them before, it is soo cool to learn through Usenet and the internet these days! Yes, the Ko and Bv abbreviations stand for 'Kondesator' and Bauvorschrift', this was all before the DIN norms kicked in, hence the presumed date of 1936 (the number in the upper right). They may indeed been inside of the famous "W38" bakelite telephone? Therre may be some among the other boxed phones, have to peek inside to see. I will put the caps up on the bay next week, wonder if they have any importance today (probably not, unlinke tubes)
We live in Germany and had no affiliations with any company, my father was just a radio/TV technician from the 1940s to 1980s. Due to some weird coincidences a few odd machines and parts ended up in our home: eg a funny looking 78rpm Thorens CD50 dual-side record player, a complete tiny 1951 Protona MD51 wire recorder spy set as used by the KGB and CIA, old telephones, tape recorders, gauges etc. In 1954 my Dad even built an entire home entertainment system cabinet (2m wide, 1.2m high !!), with 5 channel mixer, equalizer, built in bays for record player, tape recorder, tube amp and tuner, 3 way speakers, in a heavy macore case. We still operate it today, sounds still warm and great. I am slowly emptying the basement out, as all is eventually a burden I can not really enjoy (for other reasons).
Phil can sometimes be upsetting but then he often has the most correct posts on technical matters, and his statement before about the capacitors containing deadly toxic PCB oil to help insulate the paper inside the caps you have could well be correct.
I have several box-fuls of such capacitors which appear to be faily well sealed metal containers with goodness knows what sort of stuff inside them, and I've rarely ever used any that I have acquired in job lots people have donated when they gave me piles of their assorted junk. I never plan to cut one open to find out what's inside. If I ever want to use capacitors with high Vdc rating, I will always use polyester ot polypropylene metal film types which are far more reliable than anything made with paper, wax, oil, before 1949 when polyester revolutionised capcitor making.
There may be some thrills to be had when discovering ancient old gear made in Germany in the 1930s but methinks only a fool would retain the old capacitors of that era in gear which one might want to actuallly use for fun.
If the installation of brightly colored modern caps looks bad in some ancient old radio etc, then how about painting them grey to make 'em look old? Safety first. One is free to make old looking labels, and stick them onto such caps.
"Patrick Turner" schrieb im Newsbeitrag news: firstname.lastname@example.org...
Hi, then send me your gold and silver, in return you will get plastic watches and a can of golden oven paint...but first go and steal michelangelos works, we will help the italianos to get some real art in polyesterfoam...
Well, near as I can tell he's completely ignored the salient safety issue and apparently believes those old capacitors posses mystical powers of some sort so that replacing them with painted up 'inferior' modern ones is akin to replacing gen-U-ine gold and silver with a cheap plastic watch... and some gold paint to fake it up like Patrick suggested for the capacitors.
Replacing Michelangelo's works with "art in polyesterfoam" is simply repetition.
Not sure if "Bauvorschrift" is similar to a DIN standard. German post (which operated the phone network until some years ago) sometimes had their own standards which their suppliers and contractors had to fulfill. Or, in other words, "Bauvorschrift" may have something to do with the contract between german post and its supplier, but does not mean that it was a general standard.
Not sure if there were any standards concerning capacitors back then. I am involved in electronic design but have hardly ever seen any capacitor manufacturer mentioning any DIN standard in his data sheets.