How do DC to DC converter provide isolation? Do they really convert the DC input to AC and then use an isolation transformer, or is there a trick that I am missing.

Basically I am trying to isolate 24V but this does not need to be regulated so I was hoping to save space by only using the isolation portion of a DC to DC converter.

Any thoughts

 

You got the idea right. There is a transformer so DC to AC transformer AC to DC

 

Isolation may also be acheived using an opto coupler, depending on your application.

 

Here is a picture http://dsb.tracopower.com/upload/anbieter/PMS_20051129_085227_5064.JPG
You can get very small DC to DC converts. Do you need isolated power or isolated measurements?

 

Depending on your power and input \ output voltage requirements you can obtain a quite small footprint off-the-shelf.

For instance see this DC/DC converter series data sheet as an example. There would be equivalent alternatives from other manufacturers ...

http://www.murata-ps.com/data/power/ncl/kdc_nmh.pdf

 

I need an isolated power solution. I would just use a small DC to DC converter but they tend to get rather large for the 200 to 300W that I need.

It seems that optocouplers are really just an isolated switch so say a micro controller could control a non isolated signal, correct?

 

Optocouplers come in many types. they can be AC or DC and can be used to couple/isolate analog or digital signals.