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Datum: 25. 3. 2012 Projekt OBOGATENO UČENJE TUJIH JEZIKOV Primer PRIPRAVE NA POUK tujega jezika za mesec MAREC 2012 Priloga 2 Šola: Status šole: Naslov priloge: Kratek opis (vrsta in vsebina): Ciljni tuji jezik(i): Srednja šola tehniških strok Šiška partneska šola Gradivo za elektrotehniko ANGLEŠČINA Operacijo delno financira Evropska unija iz Evropskega socialnega sklada ter Ministrstvo za šolstvo in šport. Operacija se izvaja v okviru Operativnega programa razvoja človeških virov v obdobju 2007-2013, razvojne prioritete: Razvoj človeških virov in vseživljenjsko učenje; prednostne usmeritve: Izboljšanje kakovosti in učinkovitosti sistemov izobraževanja in usposabljanja. BASIC ELECTRONICS BRIDGE RECTIFIER I. WATCH THE VIDEO Basic Electronics Bridge Rectifier tutorial: http://www.youtube.com/watch?v=1pwBmGy9sz0, 6.54 http://xcircuit.sourceforge.net/tutorial/tutorial2.html http://www.tradenote.net/keyword/KBPC II. TRANSLATE THE KEY WORDS FROM THE VIDEO INTO SLOVENE. 1. bread board 2. transformer 3. output 4. input 5. coil 6. led, light emitting diode 7. capacitor 8. resistor 9. circuit 10. bend* (bend-bent-bent) 11. silver strip 12. junction 13. AC, alternating current 14. DC, direct current 15. positive terminal 16. blank 17. jumper 19. mains 20. supply 21. discharging III. WHAT IS A RECTIFIER? FILL IN THE GAPS: A rectifier is an electrical device that converts ___________________ (AC), which periodically reverses direction, to ____________________ (DC), which is in only one direction, a process known as ________________________. A device which performs the opposite function (converting DC to AC) is known as an ___________. 2 RECTIFIER, USMERNIK IV. Complete the crossword with the help of the words from the video. Half-wave rectifier application: Two level lamp dimmer. http://www.allaboutcircuits.com/vol_3/chpt_3/4.html Across Down 4. spoj 9. usmerjanje 13. razelektritev 14. trak 15. izmenični tok 16. omrežje 18. usmerjati,usmeriti(el.tok) 20. svetleča dioda 1. zviti,2.obl.glagola 2. upor 3. kondenzator 5. pol,priključek 6. izhod 7. vhod 8. prazen 10. mostiček, povezava, prevezava 11. vezje 12. enosmerni tok 17. oskrba,napajanje,dobava 19. tuljava 3 THE USE OF BRIDGE RECTIFIERS V. TRY TO ANSWER THE QUESTIONS AND THEN CHECK YOUR ANSWERS IN THE FOLLOWING TEXT. 1. Bridge rectifiers were developed about ___________ years ago. 2. They are used for powering our _______________________________________________. 3. They take household current and change it into a more _____________________________. 4. The reasons we have bridge rectifiers is the need for _______________________________. 5. Direct currrent runs most of our _______________________________________________. 6. In a power supply, the rectifier is situated between a _____________________ and a set of __________________. 7. The transformer drops the 110-volt household current down to ______________________, usually between 3 and _________volts, depending on the appliance. 8. This lower voltage, still A.C., is changed to D.C. by ______________________________. 9. The bridge rectifier, necessary for a strong, reliable supply of D.C. power, was an essential part of the ________________ revolution. 10. ________________and _______________ are prime concerns for choosing the kind of bridge rectifier to use. THE KEY WORD Unscramble the tiles to reveal a message. Created by Puzzlemaker at DiscoveryEducation.com 4 WHAT IS A BRIDGE RECTIFIER USED FOR? By J T Barett, Bachelor of Science in physics, eHow Contributor (adapted) http://www.ehow.com/about_5048018_bridge-rectifier-used.html Bridge rectifiers, developed about 100 years ago, are an essential part of powering our electronic appliances. They take household current and change it to a more useful form. Having that fundamental ability has given us stereos, computers, television and radio, as well as powerful commercial and industrial equipment. DIRECT CURRENT The reason we have bridge rectifiers is the need for D.C., or direct current. Direct current runs most of our home electronics. While it can be supplied by batteries, they have limited lifespan and power. It's better in many instances to have a strong, continuous source of D.C. We can get power from the household electrical outlet, but that's A.C., or alternating current. Fortunately, there's a way to change A.C. into D.C., and that's by using a power supply with a bridge rectifier. CIRCUITRY In a power supply, the rectifier is situated between a transformer and a set of capacitors. The transformer drops the 110-volt household current down to a safe and useful level, usually between 3 and 24 volts, depending on the appliance. This lower voltage, still A.C., is changed to D.C. by the bridge rectifier. The D.C. coming out of the rectifier is noisy and imprecise. For some uses, like a battery charger, this rough D.C. is adequate. For others, like running a stereo, the noise needs to be removed. The power is filtered by the capacitors and held to a fixed level by a regulator. BENEFITS The bridge rectifier, necessary for a strong, reliable supply of D.C. power, was an essential part of the electronics revolution, from radio and television to stereos, cell phones, and computers. Though batteries filled this need to some extent, they also added size and weight to electronic gear. Reducing or eliminating the need for batteries made equipment smaller, lighter, and more reliable. CONSIDERATIONS Current and voltage are prime concerns for choosing the kind of bridge rectifier to use. The smallest can be used to power cell phones and mp3 players. These are a few millimeters on a side with modest cooling requirements. Larger items like stereos need a bigger rectifier, possibly with a heat sink. Commercial and industrial systems like telecommunications equipment need even more power, calling for larger or multiple rectifiers with forced-air cooling. 5