So with your guys help, I’m testing the creation of a bench psu with materials I have handy. The base layer so far is the transformer out of an 18v Ryoni charger. It’s 120:21.5vac, powering the secondary side of an APC transformer. The secondary of which outputs 40.2vac. Using a rectifier circuit from an EZGO 36v battery charger I’m getting 35vdc.

is there anything inherently wrong with building off of this?

 

Outside of the obvious need for fusing and safe electrical connections for each link, no if you keep in the power/electrical safety range of the lowest rated component in the chain.

There are lots of step-up and setup-down transformers between your house and the utility power generator source.

 

If the input to the second transformer is a lower voltage than its primary was originally specified for, then you are limited by its original current specification rather than its original power specification.
(There is a bit of latitude, as the core losses will be lower at a lower primary voltage, so there can be a little more copper losses without overheating it)

 

It’s 120:21.5vac, powering the secondary side of an APC transformer. The secondary of which outputs 40.2vac. Using a rectifier circuit from an EZGO 36v battery charger I’m getting 35vdc.

How about a block diagram?

What output voltage and current do you want?

I'd be careful working with line voltage. I use this box, sometimes with a variac, for connecting things like transformers to line voltage:

 

I’ve got a variac in my future.. and yeah I should construct something like what you’ve got there, very cool.

 

The windings arent accurate as I just tweaked the turns to produce the outputs I wanted.

 

The only problem I see is the physical size. And the power is limited by the lowest power item in the string. Other than that, no issues.

 

Originally I had wanted 30v and 30a but that’s just stupid. If I can get 30v and at least say 6a I think I’ll be happy.

 

That little one doesn‘t look like 150VA to me.

 

It's not.. it's rated for 2.2a. But it's a stepped process, first is getting an adjustable regulator circuit built and tested. I've been desoldering components for quite a while so the ultimate idea is to have everything I need on-hand. Anyway once teh regulation is good, then I'll look for an upgraded transformer1 or perhaps luck into the right one to replace them both.

 

There is a second consideration about using strings of transformers, which is about power handling ability. All of the transformers in the string must have adequate power handling ability for the final load.