I have a project where I have lots of 24volt AC power and need 5 VOLT Dc. Found this goody and thought it might help others. The drawing shows a battery but I intend to snag the voltage off my transformer ( which has an overload breaker and voltage regulator )
Thoughts? Any reason I shouldnt use it? Anyone find this as exciting as I did 
http://www.dimensionengineering.com/products/de-sw050
Interesting. A couple of quick questions/comments
You say you have 24V AC. Lipo batteries are normally (only?) DC voltage sources.
Additionally, it really doubt the DE-SW*** can take AC and convert it to DC. Do you actually have an AC voltage input?
Finally, a quick ebay search turns up several (much cheaper) DC/DC solutions for converting 6.3V - 34V to 5V
See http://www.ebay.com/sch/i.html?_odkw=DC+DC+Converter&_from=R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR3.TRC1.A0.H0.XDC+DC+Converter+5V&_nkw=DC+DC+Converter+5V&_sacat=0
and
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR12.TRC2.A0.H0.Xstepdown+5v&_nkw=DC+DC+Converter&_sacat=0
Woops. I just re-read your post. I go back to my AC comment. I don’t think the DE-SW050 can take an AC signal and turn it into a DC signal. It isn’t mentioned anywhere on the datasheet that it can. You will need a rectifier or some kind.
Another ebay search http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR12.TRC2.A0.H0.Xstepdown+5v&_nkw=AC+to+DC&_sacat=0 offers several AC to DC solutions.
Thanks for the comments. As noted my POWER supply is 24volts AC not DC 
I am hoping to use this to power my core. See any reason why the device I found wont work?
Thanks for sharing more links
My power supply is 24volt because I am building on an existing device.
Update: BOO on 5 volts AC not DC!!! Thanks for checking more closely.
Yes, your main problem is that the switching regulator you linked to does not accept AC input.
You need to rectify the AC into DC (ish, a rectifier makes terrible DC on it’s own) and then smooth it and THEN regulate it to 5V.
What kind of current do you need?
Here’s what I would do:
plus
http://www.ebay.com/itm/Waterproof-DC-DC-Converter-12V-Step-Down-to-5V-Power-Supply-Module-3A-15W-BLACK-/231355599221?pt=LH_DefaultDomain_0&hash=item35ddde4975
and you should be good to go. Should cost around $10 + shipping.
Unfortunately doing that makes my super tiny mod monstrously huge. I would hack a USB wall wart first just for its small size.
I find it interesting that we have no good viable solution that is compact for 24volts ac to DC for spark. Thanks for the extra tips
to go from AC to DC is pretty simple, all you need is a bridge rectifier, there a 4 terminals on them, ~ + ~ - the + and - are the DC output and the 2 ~ are the ac input, they are super cheap and should only be a few cents, here is a search page from my local supplier Jaycar. but you will find them almost anywhere… the 1.5A should be fine for most things and you could probably get away with the 1A DIP one if your just powering the core through a step down converter. You will probably need a capacitor or three on the output of the bridge rectifier too, as you will get a fair amount of ripple on the output which may cause the step down converter to get hot or not work properly.
Thanks @hootie81 it looks like at this point I am probably best to use a battery. I just hate doing that when I have 24volts and 115volt AC handy.
I am protoing a system and was hoping somebody before me had been down this road.
I was trying to think of where i saw a good example of 24vac to 5vdc… then i remembered about the open sprinkler project. the standard transformer for a reticulation timer/valve is 24vac
Here is a good explanation of whats needed
Awesome I will go give it a read. FYI I have a strong programming background and work in a mechanical field but my electronics skills are limited So I have tons to learn and during my prototyping I am trying the KISS method as much as possible.
Thanks for weighing in!
@Hootie81 and @harrisonhjones checkout this one. 
AC to DC with voltage regulation down to 3volts AND its $2. Still bigger then I want but a step in the right direction.
Nice ebay-fu!
For those interested I went ahead and annotated the AC to DC converter @Herner linked to.
Also, datasheet for the switching regulator: http://www.ti.com/lit/ds/symlink/lm2596.pdf
Thanks for noting it all @harrisonhjones my only concern at this point is its coming from China with probably no approvals and might be a fire trap lol.
Although for $2 its better then anything I could ever build.
@harrisonhjones how about this beast? Looks to be very similar
Sadly I don’t see the rectifier which is required to do the AC to DC conversion.
The eBay item will definitely not have any approval and quality can indeed be dodgy. If time is not a huge issue you could always grab the cheapo ebay item you posted and then just build a copy yourself using legit components. It won’t be “approved” but at least you will know the quality of the parts. Shouldn’t be too hard…
The bridge rectifier is the bit that does the AC to DC, its an inline type, the black bit closest to the input.
I would have no issues using a device like that, although i would do some testing with other devices before hooking it up to a core. And make double sure the voltage output is set correctly and within the core limits before hooking it up. A bit of nail polish may help stop the adjustment screw being bumped and going out of tolerance (just make sure its not the glittery type )
But all my little girl has is glittery kind? Can I add a flux capacitor to overcome that?
I will verify output with my multimeter before hooking it up. I ordered six of them today.