On Sat, Nov 10, 2001 at 12:30:53AM -0500, Richard Sloan wrote:
> Unless you really need the 5V!
>
> I just did exactly this on a project and for me it worked out fine.
>
> My 3.3V is only at 50ma

While I agree it'll work OK with a small current range and constant temperature
I'd still have concerns about using a device that's not designed for voltage
regulation for regulation. That's just me I guess.

If you need dual voltages, simply leave the 7805 and feed the 5V into the
LM317.

But the original question was phased it's unclear as to whether or not the
5V is required.

But now rereading the question is also seems that an exact 3.3 wasn't
required. I'm now interested in what that 3.3V is going to be used for.

Personally I'd use the voltage regulator and be done with it. But I find that
I approach everything from a hobby perspective, so cost may be a significant
but undiscussed issue.

BAJ
>
> R.
>
>  >>  On Fri, Nov 09, 2001 at 02:59:15PM -0800, Chetan Bhargava wrote:
>  >>  > Hello list,
>  >>  >
>  >>  > Is it possible to achieve near about 3.3 volts out of a 7805 plus a
>  >>  couple
>  >>  > of IN4007 (1 volt drop) on the output pin?
>
>  >>  It'll have very poor regulation characteristics dependant on the diodes,
>  >>  temperature, and current draw.
>
>  >>  A much better idea is to replace the 7805 with a LM317 and a couple of
>  >>  precision resistors.
>
>  >>  BAJ
>
>  >>  --
>  >>  http://www.piclist.com hint: The list server can filter out subtopics
>  >>  (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>
>
>
>
>
>
>
> __________________________________________________________
> The Mind Factory INC
> Richard Sloan
> (613) 825-4758 phone
> (613) 825-7758 fax
> rsloan@themindfactory.com
>
> * Custom MP3 Development
> * Custom Smart Cards
> * Electronic Manufacturing
> * Hardware/Firmware/Software Design
> * Schematic and PCB layout
>
> * ALL PRICES QUOTED IN USD UNLESS OTHERWISE NOTED
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.