Update. As a result of the answers. I was able to buy this triad 100VA autotransformer. It weights exactly 1kg. so for autotransformers, it's 100VA per kg versus 50VA per kg for regular two winding transformers. Now about estimating the wattage of that unknown autotransformer. Here's the comparison with Triad branded one.
This is back of the unknown autotransformer
Well. I used my multitester and able to measure conduction in all leads between primary and secondary so it's 100% an autotransformer (the leads from the terminals was gone because I cut it so short). At least you know that in asia, autotransformer have leads coming from both sides unlike the Triad brand where it only comes out at front.
The unknown autotransformer weights 1.32kg. So it may be more than 100VA? using the formula, it's 132VA?
However, the construction seems to be different. Do you think they are same construction or really different so I can more accurate estimate the wattage of the unknown autotransformer.
I need to acquire this autotransformer from another circuit for use in other circuit that requires only 30 watts. But it's not written how many wattage capacity is the autotransformer. Based on your experience, what is usually the range of wattage of this size (it measures 3 inches by 1.25 inches)?
50 watts? 100 watts? What is your estimate (just rough estimate)?
Here it shows there is conduction measuring 18.7 ohms between the primary and secondary leads so it's an autotransformer design. They separate the leads so it's clear which is 220v, 120v neutral, and where are the lower voltage. In the US, they put the wires in one sides only right.
It's an autotransformer. I'm just asking what wattage do you think is the above?