AVR-Chat

Shervin -

Yes, you probably could, but the 555 only represents a small part of  
what would go into a switch-mode power supply. Further, the 555 is  
really designed to vary its  duty cycle or pulse width based on  
external resistors and not voltages. This makes it harder to use for  
this kind of application than one would really like. IF you REALLY  
want to experiment and learn what the challenges are for making a  
SMPS, then charge on. However, since you are posting on an AVR list, I  
would assume that your goal is to power an AVR or peripheral circuits.  
If that is the case, then you will be spending a LOT of time on  
something that really is secondary to your end goal.

I can understand, if you are in a part of the world where electronic  
components are hard to get and you may only have access to 555s and  
741 op amps and such. There are some switcher "cores" that have been  
around for a LONG time and are very low cost and widely available.   
Unfortunately, I can't find any references to what I remember, but I  
do know that they are out there. Unfortunately, if your problem is  
finding modern components, you will also have problems getting  
Schottky diodes and power inductors you really need for such a supply.

Jim Wagner

On Mar 21, 2008, at 9:03 AM, Dennis Clark wrote:

> Maybe I've lost the spirit of discovery, but I see no reason to  
> design a
> new power supply when there are dedicated switching controllers out
> there for a song (low cost).
>
> Is there a reason you want to do this the hard way?
>
> DLC
>
> > hi friends
> > have u ever worked at any switching circuits? i want
> > to design a DC power supply.may i use 555 Ic's??
> > is there any sites to help me.your ideas could help
> > me.
> > let me know if u have designed a switching power
> > supply
> >
> > thank u
> > have a nice spring holidays
> >
> > Shervin
> >
> >
> > __________________________________________________________
> > Never miss a thing. Make Yahoo your home page.
> > http://www.yahoo.com/r/hs
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
> -- 
> Dennis Clark
> TTT Enterprises
>
>
> 



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