Using Back to Back Transformers for Isolation - LOUDER AUDIO!

(The audio in the original upload was too quiet - this one is louder)

Isolation transformers are an important piece of safety equipment when working on devices that operate at mains voltages, or generate high voltages internally, such as old vacuum tube radios and other equipment.
The normal mains power has one side (the "neutral") tied to earth, so making the other side, the '"active" or "live" lead at high potential with respect to all things connected to earth, which usually includes humans, and so is very dangerous.
An isolation transformer reduces the risk of electric shock because it removes the connection from neutral to earth, making the active less dangerous to us humans that are at earth potential.
Isolation is also required when earthed test equipment, such as an oscilloscope, is going to be connected to the device under isolation.
Contacting both the active and neutral is still extremely dangerous, but much less likely to happen with normal careful practices.
However, isolation transformers can be expensive, especially those that are capable of operating at higher power levels. So a common "poor man's" method to build an isolation transformer is to wire two more common (and probably cheaper) power transformers back to back.
In this video, I investigate how well three different sized pairs of transformers wired this way perform with various power loads.
I did not monitor power loss as stated in the video, but instead monitored the input voltage required to get 240V at the load. The results may not be so apparent from the video, so they are all summarized here:-
https://imgur.com/UPKTZEL

Видео Using Back to Back Transformers for Isolation - LOUDER AUDIO! канала bertoid