Here’s’ a video tutorial from Linear Technology describing how to design a simple flyback DC/DC converter. The video promotes the use of LT’s LT3573 IC, but it also provides information that could be applied to other designs as well.
Isolated power supplies are needed in a wide variety of applications. Galvanic isolation is achieved by isolating two or more circuits using a transformer or optocoupler, and is desirable for many reasons: safety, noise immunity, circuit protection, etc. Traditionally, isolated power supplies use an optocoupler to transfer regulation information across the isolation barrier.

Think you forgot to add the link, here it is for anyone looking. Lovin all the DC/DC stuff, btw.
Whoops now I forgot it too! http://video.linear.com/isolated_dc%7Cdc
thank you
Sorry about that, we’ve been having issues with WordPress…
When it comes to push/pull, I like the LT3439: http://www.linear.com/product/LT3439
Runs at up to 250KHz, so you can use smaller toroids.
I’m using one to design an isolated +/- 5V car supply, suitable for an iPod and a CMoy amp running in a car. See notes on conflicting virtual grounds at: http://www.jdslabs.com/faq.php
Still figuring out smallest toroid, least windings & appropriate wire guage.