What you want is a standard boost converter.
Charge an Inductor to 12 amps, discharge it into the filer cap(s).
The value of inductance is determined by the frequency of the charging
pulses.
Be sure you can't saturate the inductor.
Use a good low loss flyback diode. (Schottky)

  *
  |  __O    Thomas C. Sefranek  WA1RHP@ARRL.NET
  |_-\<,_   Amateur Radio Operator: WA1RHP
  (*)/ (*)  Bicycle mobile on 145.41 MHz PL 74.4

ARRL Instructor, Technical Specialist, VE Contact.
http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Japundza
> Sent: Wednesday, January 07, 2004 9:21 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE:] dc-dc converter
>
>
> Hello All,
>
> I am looking for some ideas on building a 14v to 28v dc-dc
> converter.  The device I'm wanting to power is a 28vdc radio that
> at peak current will draw 12a.  I've seen some schematics for
> lower output circuits, but none that will do 12a.  Any ideas?
>
> Regards, Bob
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
>
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads