“Let’s clear one thing first. This is not a “Step by step -How to” guide to make your own variable isolation transformer. This is just me sharing my work, comments and ideas while building a piece of much needed equipment for my bench. Maybe it gives you a little push or sparks an idea for doing something similar.
Whether you are diagnosing a broken piece of electrical equipment or testing a repaired one, there comes a moment when you have to plug it into mains. That moment is like playing a lottery. Everything could work out great or it could go BOOM and trip your apartments fuse. Not once did I repair something and only way to test it was plugging it to mains and hoping for the best. Lots of times everything worked out great, but other times, one missed component caused even worse problem and destroying all the new parts.
Tripping the fuse could be avoided by a simple isolation transformer. But why stop with a simple solution when you can complicate your life and spend your time and money on something more versatile.
Variable isolation transformers exist as a commercial unit. One of the more interesting is models is: Sencore PR570
But… there were three big obstacles stopping me from buying a commercial unit:
1. General unavailability in my country
2. Total cost (unit, transport and import taxes)
3. Physical size
Last obstacle was the biggest problem of all (pun intended). Since my work area is very limited so is my bench space. And I just couldn’t find any product that would fit my small desk. So, I decided to build my own. Device, not a desk 😊.
Every component used in a design of this VIT (Variable Isolation Transformer) was a compromise between the physical size of the unit and usability in everyday work.”