I have a design that uses a 12v wall wart power supply because an LCD needs the 12v. The main circuit runs on 5v and 3v. In the prototype I have a 5v regulator (LM340TS) dropping the 12v to 5v and a 3v regulator (TPS7230QP) that drops 5v down to 3v. This device will be on all the time. I have a heat sink on the 5v reg and it gets hot. I want to put the finished circuit in a project box with vents but no fan. My question is: is there an easy, low cost, solution to implementing a switcher to drop the 12v to 5v? Is this done? The 3v reg does not provide much power so it is not a problem. Thanks, --BobG -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Bob Ammerman Sent: Tuesday, July 17, 2001 8:23 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected ----- Original Message ----- From: "Roman Black" To: Sent: Tuesday, July 17, 2001 5:43 AM Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected > Hi Bob, many of those 3-light fittings are NOT suitable > for larger bulbs. The socket itself might be ok but > the fitting won't take the total watts heat. > > My 3-light kitchen fitting gets over 85 degrees C (yes > I have a infrared thermometer) with 60w bulbs in it. > > When your bulb goes on/off intermittantly the filament > has failed. Broken filament. You're relying on luck > to make it connect. :o) Also, the symptom of the bulb > separating glass from the metal cap is a sure symptom > of excessive heat, fatiguing the solder that holds them > together. I guess your kitchen lights are on a lot, > and it gets hotter in there than other rooms, and you > have 3 larger bulbs as kitchens need a lot of light. So, if the bulbs can't stand the heat they should stay out of the kitchen? > Try 2 compact fluoros in there, will reduce the heat > to almost nothing, and give good light. My kitchen > now has them. :o) > > I also suggest checking the temperature of your home > light fittings, you might be surprised how dangerous > they are, most wiring cables are rated at 85'C and > my lights were at that temperature or higher... > -Roman > > > Robert E. Griffith wrote: > > > > Thanks for the suggestions. Here are some facts: > > > > * The bulbs are incandescent, not halogens. > > * The fixture is hanging from the ceiling, 3 bulbs, each with a metal > > reflector above it - looks like plenty of ventilation to me. > > * Each socket is rated for 100w. > > * All three bulbs that separated were 60w. > > * We have used 60w and 100w bulbs - failure rate is about the same. > > * The mysterious off again / on again bulb is 100w. > > * Thermal shutoff cannot explain mysterious bulb because it will not light > > even when fixture has not been used for hours and I measured the voltage in > > its socket while it was not working. > > -- > 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 > > -- 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 -- 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