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Carlb1058
16-08-2013, 04:38 AM
Hi All,

I'm trying to find a Toroidal Transformer with the following which is the last part required for the frankentroller I've built;
Primary: 220v
Secondary: 18v*
Secondary: 36v*

* both connected to the spindle controller board which then also splits off to 24v for the steppers

Now I've contacted a few mobs here downunda, and they have all said 'what is the va?'

How do I find out what the va is?

TIA

Web Goblin
16-08-2013, 07:06 AM
The VA rating is basically the output power of the transformer. Its the ouput voltage of the secondary winding multiplied by the current it can supply. So for a secondary voltage of 36 volts and a current of 2 amps it would be 72VA. Bigger transformers can be rated in KVA.

Carlb1058
16-08-2013, 08:36 AM
The VA rating is basically the output power of the transformer. Its the ouput voltage of the secondary winding multiplied by the current it can supply. So for a secondary voltage of 36 volts and a current of 2 amps it would be 72VA. Bigger transformers can be rated in KVA.

'scuse ingnorance, how did you get 2 amps? I found a mob willing to make me one but still need all these numbers :dread:

Web Goblin
16-08-2013, 09:30 AM
2 amps was just an example number to show how to work out the VA rating. For your application you need to figure out the total load in amps that will be taken from the secondary winding of the tx and then multiply that by the voltage to get the VA rating.
As for getting one made is it not easier to buy two seperate ones of the correct rating rather than getting it made?
They come in a multitude of various ratings straight off the shelf.

The link below is to rs components.

http://uk.rs-online.com/web/c/power-supplies-transformers/transformers/toroidal-transformers/?sort-by=default&sort-order=default&applied-dimensions=4294501648&lastAttributeSelectedBlock=4294513227

irving2008
16-08-2013, 12:18 PM
Unless I missed something, whats wrong with using the existing toroidal?

Carlb1058
17-08-2013, 12:07 AM
Unless I missed something, whats wrong with using the existing toroidal?

No not missed nothing, just want another to run the spare spindle controller I've got and the m542's instead of having to a) have two psu's or b) gut my existing controller that actually works just for the toroidal - essentially I wanna keep the Chinese controller as an emergency backup.

Carlb1058
17-08-2013, 12:50 AM
Okuls - a touch of clarity, should have done this to start with.

The Chinese controller went tits up, turned out it was the spindle/stepper controller board which was replaced under warranty. When they sent the replacement, attached to it was a spare IRF 630 (from mem) chip which meant I could fix the original as well (bonus).
Now when I was putting together a better controller with the M542's and a bob a PSU was required so I bought one off eBay but couldn't for the life of me work out where the spindle went, a post here told me I need another PSU to run the spindle.

I honestly can't see the logic in running two PSU's so thought I'd make use of the original (now repaired) spindle/stepper controller board and just buy a toroidal the same as what's in the original controller box, which meant I could still knock stuff out with the original while fiddling and fine tuning the new controller box.
Unfortunately, I've found one only company willing to even consider it here in australia and until I can come up with exact specs they won't even bother starting but they 'are' willing to price it $150 plus shipping which is what ₤90 plus shipping.

The attached pic is the basic idea, the 24v to the M542's will obviously be split for three + and three -

9522

Carlb1058
17-08-2013, 07:54 AM
Call this post closed, sorted, whatever :) Just bought another complete Chinese controller box for what it would cost for a single toroidal here, so I'm going to gut my existing one and use the bits in the Frankentroller with the M542's - getting closer woohoo

Thanks for the input though gents, as always answers are greatly appreciated even if I have no idea most of the time :hysterical: