Searching \ for '25v at 5 Amp ????' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=25v+amp
Search entire site for: '25v at 5 Amp ????'.

Truncated match.
PICList Thread
'25v at 5 Amp ????'
1998\12\11@181235 by Ricardo Ponte G

flavicon
face
       Hi Picers:


       I«m not sure if it«s a dream or not but:

       Some out there have deal or have saw some regulators like 7805 with 25v
at
5 or more Amps in its output ????


       Thanks for sharing your expericence.

1998\12\12@002758 by Michael Hagberg

flavicon
face
you can get standard 3amp devices and i think i've seen a spec that
parallels the outputs to increase the amperes.

michael

You may leave the list at any time by writing "SIGNOFF PICLIST" in the
   body of a message to spam_OUTLISTSERVTakeThisOuTspamMITVMA.MIT.EDU.

-----Original Message-----
From: Ricardo Ponte G <.....rniniverKILLspamspam@spam@CANTV.NET>
To: PICLISTspamKILLspamMITVMA.MIT.EDU <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU>
Date: Friday, December 11, 1998 5:26 PM
Subject: 25v at 5 Amp ????


       Hi Picers:


       I«m not sure if it«s a dream or not but:

       Some out there have deal or have saw some regulators like 7805 with
25v at
5 or more Amps in its output ????


       Thanks for sharing your expericence.

1998\12\12@015031 by Eric Borcherding

picon face
Try a LM350 in a steel case with good heatsinking

1998\12\12@091427 by paulb

flavicon
face
Michael Hagberg wrote:

> you can get standard 3amp devices and i think i've seen a spec that
> parallels the outputs to increase the amperes.

 It is probably easier to use one or more PNP power transistors (MJ2955
or similar/ better) with emitter to unregulated supply, base to input of
the regulator, and collector to output of the regulator which is the
main regulated output.

 A 0.3 ohm resistor from emitter to base causes 2 amps to be passed
by the regulator before the transistor(s) conducts; the remainder of the
25 amps is passed by the transistors.  If more than one are paralleled,
0.02 ohm resistors are put in each separate emitter lead to equalise
their contributions.

 This arrangement defeats the current and thermal limiting features of
the regulator, though the latter will still occur if it is mounted on
the same heatsink and close to the transistors.
--
 Cheers,
       Paul B.

1998\12\12@191021 by Mike Keitz
picon face
On Fri, 11 Dec 1998 07:09:17 -0400 Ricardo Ponte G <EraseMErniniverspam_OUTspamTakeThisOuTCANTV.NET>
writes:

>        Some out there have deal or have saw some regulators like 7805
>with 25v =
>at
>5 or more Amps in its output ????

Such IC's are made, but they're kind of expensive.  A simple and cheap
approach is to combine a standard 1.5A 3-terminal regulator with an
external power transistor to boost the current.  Unfortunately with this
circuit, the transistor is not protected from burning out in case of an
overload.  A more complicated version adds another transistor to limit
the current through the current-boosting transistor.  Both circuits are
described in the application circuits in the back of most regulator data
sheets.

Any linear regulator with 5A of current flowing through it is going to
dissipate quite a bit of heat.  It is likely that the heat sink will be
the most expensive and unweildly part of the project.  For that reason,
switching regulators are very popular for these higer powers.  The new
all-in-one switching IC's are reasonably easy to use.


___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]

More... (looser matching)
- Last day of these posts
- In 1998 , 1999 only
- Today
- New search...