Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!ux1.cso.uiuc.edu!tuna.cso.uiuc.edu!kline
From: kline@tuna.cso.uiuc.edu (Charley Kline)
Newsgroups: sci.electronics
Subject: Re: 7805 woes
Keywords: Latch off
Message-ID: <1989Nov7.233936.24863@ux1.cso.uiuc.edu>
Date: 7 Nov 89 23:39:36 GMT
References: <12236@fluke.COM>
Sender: news@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 37

In various articles, various people write:
about power supplies based on 78xx regulators.


I've been slapping together 5v power supplies for years with a fair amount
of success using the following. Anyone see any room for improvement without
driving up the cost? Yes I know I can use a 723 and 2N3055 power transistors
and do better, but that also would about double the cost of this.

Oh incidentally, THANKS!! to everyone who replied to my query about
replacement triacs for our dimmer packs. I ordered ten from Mouser to
get their quantity discount, and had to use one of them to replace a
triac that blew when an instrument shorted. It worked great. I'm
somewhat of a hero now because our little theatre is just about flat
broke and I saved a $80 service call to the local head band lighting
and sound joint. I tried to give credit to sci.electronics, but none of
the fine-arts types at the Station really comprehended what it is. :)


			                 7805
                  +-----+             +-------+
<-----B|B---------|ac  +|---+---------|in  out|-------+------> +5
      B|B         |     |   |         |  gnd  |       |
120AC B|B T1      | B1  |   =C1       +-------+       =C2
      B|B         |     |   |             |           |
<-----B|B---------|ac  -|---+-------------+-----------+------> gnd
                  +-----+


T1 -   6.3v, 1.2A secondary power transformer.
B1 -   1.5A 100v bridge rectifier.
C1 -   2000uFd 16V electolytic
C2 -   47uFd 16V electolytic

_____
Charley Kline, ATD and gadgeteer, Celebration Company at the Station Theatre
c-kline@uiuc.edu