Path: utzoo!censor!geac!torsqnt!lethe!yunexus!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!decwrl!asylum!osc!jgk From: jgk@osc.COM (Joe Keane) Newsgroups: sci.electronics Subject: Re: 12 to 9 volts dc (kinda long) Summary: Use a regulator. Message-ID: <4574@osc.COM> Date: 26 Feb 91 22:51:49 GMT References: <1991Feb10.220719.17078@cbnewsl.att.com> Reply-To: jgk@osc.COM (Joe Keane) Organization: Versant Object Technology, Menlo Park, CA Lines: 20 In article erk@americ.UUCP (Erick Parsons) writes: >This is a pretty basic circuit but works well as a regulator. After all >this though, I would have to agree with about everyone else in saying ... >Get a 9V regulator chip ! I mounted one for my Watchman TV (actually 6V) into >a cigarette lighter plug. I heat sinked it through the metal contact clips >which contact the lighter receptacle *AND* drilled 8 holes in the thing >for some air flow. The thing gets warm but not half as warm as it did when >it wasn't heat sinked !! Worked from Sacramento to Las Vegas without a >hitch, about an 8 or 9 hour drive. I have to second the comment about using a regulator chip. Anything you hack together from discrete components probably won't compare. Those little guys have lots of transistors, so duplicating their functionality would be costly and take up a lot of space. Their performance is generally very good, with wide input tolerance and very low output impedence. But the more important issue is what happens under abnormal conditions. Most regulator chips have current foldback and thermal shutdown so they won't burn out or fry your device when things get bad. This is what distinguishes a good circuit from a hack.