The B22 bayonet base (rather unusual in Central Europe) could be an idicator of usage where vibrations could unscrew any Edison base. Maybe in a bus? The 72 voltage made me think about the classic telephone system voltage which has/had a similar value. Or was it for serial connection? I hope someone unveils that mystery.

I think it was intended for use on serial circuit in chandeliers but I have some of them with 90v which is a weird voltage as well.

I think it was intended for use on serial circuit in chandeliers but I have some of them with 90v which is a weird voltage as well.

I fancy the bus or train idea besides the use in a "Telefonkabine". A Petrol pump could also be an option. The series presumption combines many problems: Which lamp is broken? Why serial? The unsusual shape. The difficulty to get that voltage.

You have some real gems here! Congratulations!

Huh?? Indeed very strange voltages. Do you have examples for chandeliers?? Luxram,was that a part from Osram as seen the lightbulb logo is the same??

Thanks Headgardner.

Arjen, ai have no idea how the intended fixture looks like. In fact, I firstly wanted to apply 230V on such bulb but on the last second I discovered that the number “90” and on the other lamps “72” appies for the voltage so I connected them to the variac and increased the voltage, already on 40V the bulbs were quite bright.

Thanks Headgardner.

Arjen, ai have no idea how the intended fixture looks like. In fact, I firstly wanted to apply 230V on such bulb but on the last second I discovered that the number “90” and on the other lamps “72” appies for the voltage so I connected them to the variac and increased the voltage, already on 40V the bulbs were quite bright.

I just posted a (very small) picture of fixtures where these lamps are still in use.