It is called a "switching power supply." It works very differently from the traditional transformer-rectifier power supplies (linear power supplies) you may be familiar with. In simple terms it is an oscillator that produces a high frequency square wave going from zero volts to some positive value (the value depends of the output voltage you are trying to get). This square wave is then filtered to provide the desired DC voltage. The output voltage is monitored and a feedback loop turns the oscillator on and off to keep the output voltage at the desired value.
One advantage of this system is that it will accept a wide range of voltages and frequencies. The feedback loop determines what comes out. Another advantage is that it can be made small and lightweight because the oscillator's transformer runs at high frequencies. Such transformers are small and light. Such a system also does not produce much heat because it does not have to burn off excess power. It simply shuts off when the voltage is the desired value and turns back on as the voltage drops. The on-off switching occurs many times per second. >I am going to Spain next month (240v). I noticed my tiny Toshiba power >supply says input: 100-240 volts, output: 19v. >Are you saying that I do NOT need a step-down transformer? How does the >transformer detect and switch modes? ************************************************************************ * ==> QUICK LIST-COMMAND REFERENCE - Put the following commands in <== * ==> the body of an email & send 'em to: [EMAIL PROTECTED] <== * Join the list: SUBSCRIBE COMPUTERGUYS-L Your Name * Too much mail? Try Daily Digests command: SET COMPUTERGUYS-L DIGEST * Tired of the List? Unsubscribe command: SIGNOFF COMPUTERGUYS-L * New address? From OLD address send: CHANGE COMPUTERGUYS-L YourNewAddress * Need more help? Send mail to: [EMAIL PROTECTED] ************************************************************************ * List archive from 1/1/2000 is on the MARC http://marc.info/?l=computerguys-l * List archive at www.mail-archive.com/computerguys-l@listserv.aol.com/ * RSS at www.mail-archive.com/computerguys-l@listserv.aol.com/maillist.xml * Messages bearing the header "X-No-Archive: yes" will not be archived ************************************************************************
