Post by thread:Power Supply question from Book:Programming & Cust

Hi all, Sorry for referring to a book, but my question is about a powersuppy diagram >from the book "Programming & Customizing the Pic Microconrtoller" by Myke Predko. I've been playing around with the PIC16C54/JW using an 4x20 LCD, and I want to move it from the carrier board I'm using, and want to make my own "small" board. The question I have is in regards to powering this thing. The manual says that the pic I'm using will work from 3.0 - 5.5v, and the book on page 241 shows a diagram of such a power suppy, my question is what is the "7805" indecated in the box? And is it safe to assume that the "Vcc" at the top right does to my PIC? -Kam (^8* =============== Kam Bansal (^8* spam_OUTkambTakeThisOuTjps.net "Save this email in a smaller font to save on disk space"

>page 241 shows a diagram of such a power suppy, my question is what is the >"7805" indecated in the box? And is it safe to assume that the "Vcc" at the top >right does to my PIC? THe 7805 is an ancient-technology 5V (that's what the 05 means) linear regulator. It changes V into Heat. The 78-series parts are positive regulators, the 79-series are negative. Andy ================================================================== Andy Kunz - Montana Design ==================================================================

Kam The 7805 "in the box" is the part number for a very common voltage regulator. It will basically take your input voltage from your wall transformer (Wall Wart) and convert it to a steady 5 volt. Pick up a basic electronics text book at your library and you are sure to find a very detailed explanation of the 7805 and also some usefull circuits. Charles >Date: Mon, 16 Feb 1998 23:49:37 GMT >Reply-To: pic microcontroller discussion list <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> >From: Kam Bansal <kambKILLspamJPS.NET> >Subject: Power Supply question from Book:Programming & Customizing The {Quote hidden}> pic...by Myke Predko >To: .....PICLISTKILLspam.....MITVMA.MIT.EDU > >Hi all, > >Sorry for referring to a book, but my question is about a powersuppy >diagram from the book "Programming & Customizing the Pic >Microconrtoller" by Myke >Predko. I've been playing around with the PIC16C54/JW using an 4x20 >LCD, and I want to move it from the carrier board I'm using, and want >to make my own "small" board. The question I have is in regards to >powering this thing. The manual says that the pic I'm using will work >from 3.0 - 5.5v, and the book on page 241 shows a diagram of such a >power suppy, my question is what is the "7805" indecated in the box? >And is it safe to assume that the "Vcc" at the top right does to my >PIC? > > > -Kam (^8* > ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

Hi Kam, The circuit shown on Page 241 is a pretty typical small system power supply and is probably the cheapest actively regulated one you can build. As Andy indicated, the 7805 is pretty old technology, but it's cheap and won't burn out if you accidentally short circuit it. For most projects, I tend to use the 78L05 which can source up to 100 mA, requires very little parasitic current from the source (which makes it reasonably well suited for battery powered applications) and costs about $0.50 more than the 7805. "Vcc" goes to "Vdd" on the PICMicro (Look at the schematic on Page 240 and you'll see what I mean). Good luck on your project! myke {Quote hidden}>Hi all, > >Sorry for referring to a book, but my question is about a powersuppy diagram >from the book "Programming & Customizing the Pic Microconrtoller" by Myke >Predko. I've been playing around with the PIC16C54/JW using an 4x20 LCD, and I >want to move it from the carrier board I'm using, and want to make my own >"small" board. The question I have is in regards to powering this thing. The >manual says that the pic I'm using will work from 3.0 - 5.5v, and the book on >page 241 shows a diagram of such a power suppy, my question is what is the >"7805" indecated in the box? And is it safe to assume that the "Vcc" at the top >right does to my PIC? > > > -Kam (^8* > > >=============== >Kam Bansal (^8* >EraseMEkambspam_OUTTakeThisOuTjps.net > >"Save this email in a smaller font to save on disk space" > > Opus: There's a 465 pound woman pruning her azelias while wearing a pink stretch bodysuit. 911 Operator: So what's the emergency? Opus: From a taste perspective, it's a crisis of biblical proportions!

> The circuit shown on Page 241 is a pretty typical small system power supply > and is probably the cheapest actively regulated one you can build. As Andy > indicated, the 7805 is pretty old technology, but it's cheap and won't burn > out if you accidentally short circuit it. For most projects, I tend to use > the 78L05 which can source up to 100 mA, requires very little parasitic > current from the source (which makes it reasonably well suited for battery > powered applications) and costs about $0.50 more than the 7805. Hardly $.50 more... $.25 each from JDR. Manufacturer varies... Locally 7805 and 78L05 are about $.60 each. Orin.