I don't know what the maximum voltage input on a 7805 is, but I have used them at
28V.  The big problem with using them with higher voltages is that they dissipate
a lot of power.  At 30V input is is 30V-5V+25V times 1A=25W of heat dissipated.
I manufacture some devices that run on 28V and don't have room for a heat sink on
the regulator so I use a 12V zeener in series with the input voltage to knock it
down some.

There are some switching regulators that work up to about 50V and don't generate
a lot of heat, but they are a whole lot more expensive than a 7805.

"Robert A. LaBudde" wrote:

> At 12:19 PM 2/12/00 -0600, you wrote:
> >Has anyone found a 5V Voltage regulator with an output of approximately 1A..
> >that can handle a 30+ Volt input?
>
> 1. Use two 1A regulators in series, with decreasing control voltages.
>
> 2. Use a switching supply to reduce wastage.
>
> ================================================================
> Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ral@lcfltd.com
> Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
> 824 Timberlake Drive                            Tel: 757-467-0954
> Virginia Beach, VA 23464-3239                   Fax: 757-467-2947
>
> "Vere scire est per causae scire"
> ================================================================