Switching voltage inputs with a chip

The switching regulator is increasing in popularity because it offers the advantages of higher power conversion efficiency and increased design flexibility (multiple output voltages of different polarities can be generated from a single input voltage). This paper will detail the operating principles of the four most commonly used switching converter types: Buck: used the reduce a DC voltage to a lower DC voltage. Boost: provides an output voltage that is higher than the input. Buck-Boost (invert): an output voltage is generated opposite in polarity to the input. Flyback: an output voltage that is less than or greater than the input can be generated, as well as multiple outputs. Also, some multiple-transistor converter topologies will be presented: Push-Pull: A two-transistor converter that is especially efficient at low input voltages. Half-Bridge: A two-transistor converter used in many off-line applications. Full-Bridge: A four-transistor converter (usually used in off-line designs) that can generate the highest output power of all the types listed. Application information will be provided along with circuit examples that illustrate some applications of Buck, Boost, and Flyback regulators. ______________________________________________________ Want to get-on Google's first page and loads of traffic to our website? Hire a SEO Specialist from Ocean Groups[url=http://oceangroups.org/] seo pecialist [/url]

. Many headphone jacks have a switch on the end that the plug actuates when inserted. Same basic principle as the part kelseymh mentioned and (usually) easier to find.

You don't need a chip, just a three-lead jack for the power adapter. For my own projects, I used RadioShack's 274-1582, Size M panel-mount socket with switch. It works by having a small lever switch that is pushed out out of the way when you plug in the adapter. With appropriate wiring, you can have your device switch between the external power vs. internal batteries, just by unplugging the jack.