How to increase capacitance of home made power supply?

[Syllith]

No, unfortunately I cannot. It is covered by plastic that's been heat pressed to the transformer housing. I cannot see inside.

[Cliff Matthews]

So it seems you have in-phase paralleled Blue and blue/white (4.5 ohm) with the Brown and white/black (3.2 ohm) winding then?
If so, that would explain a 6% increase, but now the Blue and Blue/white is not carrying much current.. I would only parallel identical windings without access to view the core entry points.

Have you left this powered up (but unloaded) for more than 15 minutes? (without much more than slight warmth on the core?)

[Syllith]

When I was building the tone generator for it, it was my main power source. It wasn't drawing much current but it ran for a long time. It was nice and cool. I powered a kenwood radio and a single speaker for about 5 minutes one time and it was fine as well. Just not a lot of current to keep the cap charged up.

[Syllith]

So I think I may have found the best combination for this transformer. Connecting the brown + white/black wire (the one that seems to produce the most current) and used the yellow pair (8.8VAC) and that actually bumped it up to a solid 14V at idle and with a car stereo playing a single speaker at full volume, it only dropped to about 12V or so. This is more what I was expecting from this transformer

But... It's still not enough. I'm starting to realize that even though the transformer is physcially large, it has 4 different outputs and at least 3 inputs. There's a lot going on and it doesn't seem to carry nearly as much current as I original thought.

So in that case, I think I'm either going to find another one that fits my application, build my own, or custom order one (probably from Agile Magnetics). Depends on the cost. It's worth calling for at least a quote though. Unless anybody knows of a transformer that'd be able to provide about 5A at 12-24 volts. I don't mind if it's over 12 because I can just regulate it from there. This way I can make it variable.

[Cliff Matthews]

**Can you measure the core size to get an estimate on VA rating?

$25 can buy something more efficient (and not so heavy to ship..)
Meanwell RS-150-12 (11.4-13.2v adj) or the RS-150-15 (14.25-16.5v adj)
http://www.mouser.com/ProductDetail/Mean-Well/RS-150-15
http://www.mouser.com/ds/2/260/RS-150-SPEC-806251.pdf

[Cliff Matthews]

That 8.8v winding sounds like it's doing its job, since without a load you would see about 10VAC (~14vdc rectified). Another way to get to where you want to go is doing a $10 "slow boat from China order" on a 300w DC-DC Buck converter. Then you can use the grey, the orange, or even the grey+yellow as input to the converter (pre-adjusted to a typical 13.8v) with a cap on both sides to keep the audio loose and lively. http://www.ebay.com/itm/300W-DC-DC-CC-CV-Buck-Converter-7-40V-to-1-2-35V-8A-Step-down-Power-Module-/261530423651

[Tcucore]

I've been using a 3.5 amp fuse on my power wire and when I test, I move it to the center of my shop and power it from a distance with a switch. I have yet to short it out. I have also not made any changes to it at all yet. I'm doing my research before I go further. Anything I'm unsure of I will ask about first.

you should be aware that power at the primary must equal power at the secondaries (cumulative).  This means if you are sourcing 3 amp at a 12.5V secondary (for example) with a 125V primary, the current drawn from the primary is reduced by a factor equal to the voltage reduction from primary to secondary.  Use the following expression to determine a reasonable primary fuse, otherwise your 3 amp fuse my never trip during a short.

(Primary Power = Secondary Power )  therefore (Primary Voltage * Primary Current) = (Secondary Voltage * Secondary Current).  Use a slow-blow so the initial inrush doesn't blow it when you turn your supply on.

Additionally, I have a Triad power transformer I've never used.  It's rated for 10A with a 20V secondary.  If you are interested, I'll mail it to you at cost for shipping.  I'm currently using it as a book-stop on my shelf.