Tested: Mirabella Vintage Style Filament 25W Clear ST58 E27 Decorative Globe

While I have looked at some vintage filament style globes in the past and come to the conclusion that they’re absolutely horrid for energy efficiency, they do have a visual appeal. This week, while rummaging through a thrift store, I came across one that I had seen previously in a K-Mart, selling for $3. I didn’t really need it, but I felt like it was visually worth it just to grab it for a bit of entertainment. What’s life without a bit of whimsy?

The Globe

The globe comes packed in a colour cardboard box, decorated with a black and white vintage motif that really makes the product stand out with its golden glow. The box gives the globe as 25W with an ST58 “style” on an E27 Edison Screw base. Aside from that, there is really not much information – we aren’t told about the lumens it generates, we’re not told about the lifetime either (which I can’t imagine to be too great given the almost comical amount of filament they’ve packed in). I suppose part of the reason is that it’s being sold as a “decorative” globe – perhaps they don’t need to provide this information. At least it does have a regulatory compliance mark, not that they really needed it.

The globe itself looks only to have the slightest evidence of glass tinting. It has a bit of an “octopus head” shape, almost reminiscent of a mercury arc rectifier tube.  The bulb is rather long, with a gold-coloured cap with the Mirabella logo pressed into it. It claims to be a 25W globe, at 240V rather than the harmonised 230V. This means it should last longer in Australia where we were officially a 240V country and line voltages often are even a little higher than that.

The filament is extremely thin and hard to image even with my macro lens. If it is coiled, I can’t see it!

The filament supports at the ends are like “spider’s legs”. From the top, we can see a total of ten supports.

From underneath, there are nine supports with the filament coming in on two wires.

At a guess, there is probably close to two meters of filament in the globe, which seems quite long.

Testing

As with a thrift-store purchase, everything is “as-is”, and with such fine filaments I was concerned that it may have been damaged in transit. However, a quick check proved that the globe was still functioning with a very distinctive look matching the one on the box. A check of the colour temperature shows it is about 2400K according to the camera.

A look at the globe from the bottom end shows the warm glowing filaments reflected from the oddly-shaped glass envelope.

Near the supports, the filaments seem to cool enough that they aren’t producing much light. However, as a 25W globe, it doesn’t really do too much for light nor heat generation, so I’d say the characterisation of the globe as a “decorative” one is spot on.

Testing it on the variac with the Tektronix PA1000 shows that across the voltage range, the globe behaves with a power relationship between power and voltage. The actual power is about 23.5W at 240V, so slightly underpowered.

Conclusion

I decided to buy this globe from a thrift shop for a bit of entertainment, and it certainly looks a little strange with the amount of filament wrapped inside. But it does work, although very little is said about lifetime or luminous output. As a decorative lamp, it’s certainly pretty and mine seems to be a little under powered.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
This entry was posted in Lighting and tagged , , . Bookmark the permalink.

Error: Comment is Missing!