Power / isolation transformers to mount in 1U cases

Revisiting a perennial topic - I am hunting for power transformers to fit in 1U cases.  The vigortronix VTX 126-006-215 is OK for low current consumption devices but I'd like something with a higher power rtaing 12 VA, 15VA, etc, which will still fit within a 1u case

Typically I need them to mount on the side of the chassis so the thickness or C dimension (most transformer data sheets seem to use the same convention) must be 40mm +/-

I'd prefer transformers with flying leads but these seem to be unavailable

Typically I buy 15-0-15 but have a need for 18-0-18 at about 14 VA


Nick Froome

Toroidal ones not an option?

Khron said:

Toroidal ones not an option?

Click to expand...

Good question. In 99% of cases, no

Virtually all transformers are mounted vertically on the side panel and top and/or bottom panels are removable. This makes toroids hard to fit. Although they meet the hight criteria they're generally too large to fit the original space

These transformers are to fit existing equipment

Nick Froome

I don't know man, I have built tons of 1u equipment using 15v and or other 18v  25va toroids I got off mouser, digikey, eBay, etc... Amazon even carries some now.
I believe Don Audio has a toroidal with the specs you want.

Well, if "damn near impossible to find" and/or "gonna cost you an arm and a d*ck" is preferable to "hard to fit", i guess that's your problem :

But, if you choose to be more pragmatic(?)... How often do those pieces of gear need both the top and the bottom cover removed? I mean, realistically. I should hope, not all that often. If that's the case, bolt the toroids to the lesser-removed cover, and be done with it. But that's just me...

pvision said:

Good question. In 99% of cases, no

Virtually all transformers are mounted vertically on the side panel and top and/or bottom panels are removable. This makes toroids hard to fit. Although they meet the hight criteria they're generally too large to fit the original space

These transformers are to fit existing equipment

Nick Froome

Click to expand...

Unless all the electronics is mounted on the front panel I would have thought it highly likely there is some already on the bottom panel in which case adding a toroid there is the obvious answer - or is there something odd about these existing pieces of equipment.?

Cheers

Ian

pvision said:

Virtually all transformers are mounted vertically on the side panel and top and/or bottom panels are removable.

Click to expand...

The problem is that standard EI type transformer for higher power than 8-10VA cannot fit in 1U. (EI48-18 is the max, IMO)
EI48-18 or 24  type of transformer you can find on eBay.

This makes toroids hard to fit. Although they meet the hight criteria they're generally too large to fit the original space

Click to expand...

You can use a  L-bracket  and mount this transformer inside to the side panel. It will fit, IMO.
https://www.tme.eu/en/details/55102-p1s2/toroidal-transformers/talema/

These transformers are to fit existing equipment

Click to expand...

DBX166?

Thanks for the TME link

That dbx installation is pretty much exactly what I have to deal with. It seems you can't buy transformers with flying leads any more (apart from toroids) and most conventional transformers are mounted / packaged / oriented wrong for what I want to do

Nick Froome

Try contacting Transformer Equipment ltd in Sandwich.

They are very helpful with custom made transformers at reasonable prices even for prototype / one offs

ruffrecords said:

Unless all the electronics is mounted on the front panel I would have thought it highly likely there is some already on the bottom panel in which case adding a toroid there is the obvious answer - or is there something odd about these existing pieces of equipment.?

Click to expand...

Good point. But quite a lot of electronics has a pcb mounted on brackets / rails etc attached to the side panels. So you can remove the bottom panel and typically access the solder side of the pcb. And also remove the top panel to access the component side.

Found a couple of interesting things recently. First is a bracket for mounting toroidal transformers. Easy enough to DIY but finding steel or aluminium angle in the correct dimensions has proved difficult

https://www.audiophonics.fr/en/transformers-accessories/mounting-bracket-for-toroidal-transformer-o150mm-p-6039.html

More brackets of different designs

https://toroid.com/Products/Mounting-Hardware/Vertical/Omega-Bracket

https://www.nuvotem.com/en/laminate_replacements.shtml

http://scemosystems.fi/en/toroid-transformer-mounting-bracket-set-90-45mm

https://www.musikding.de/Toroidal-transformer-mounting-kit-70mm


I have bought a couple of toroids and fitted them to dbx 160XTs. They are a tight fit and it's worth noting that the dimensions quoted can be pretty inaccurate as the wrapping & cable exits are not at all uniform

These leave sufficient height clearance that the mounting bolt is clear of the top panel by a good 5 mm to avoid a shorted turn

https://www.rapidonline.com/Vigortronix-VTX-146-015-115-Toroidal-Transformer-230V-Single-Primary-15VA-0-15V-88-5183

This toroid has a void at the centre. Some have a solid centre with amounting hole. Each has their advantages & disadvantages

Nick Froome

My favorite psu transformer supplier "Toroidy" - https://sklep.toroidy.pl/en_US/index - can do epoxied-centre with cast-in nut for mounting, voiding the need to go through..

They are super helpful people - you'll want to talk to Tomasz Lachowski, he comes through as having a deep understanding of the needs in audio.

Also, the couple of times I had small orders with them, I was really surprised about how cheap they could do small batches and single ones. Just ask Tomasz for a quote, can't hurt to know what they can do..

/Jakob E.