Práctica 7.docx - INSTITUTO POLITÉCNICO NACIONAL ESCUELA...

This preview shows page 1 - 4 out of 11 pages.

ANALOGUE ELECTRONICS PRACTICE REPORT 7: LEVEL COMPARATORS AND APPLICATIONS. PROFESSOR: ISMAEL CERVANTES DE ANDA. MEMBERS: CORTEZ TINOCO ALEJANDRO. FONSECA MIRA DANIEL ESTEBAN. RAMOS RAMÍREZ ANTONIO. OBJECTIVE: Check the use of the comparators simples and with hysteresis. Make with the simple comparators some applications. Make with the hysteresis comparators some applications. Interpret results obtained. INSTITUTO POLITÉCNICO NACIONAL ESCUELA SUPERIOR DE CÓMPUTO
Image of page 1

Subscribe to view the full document.

INTRODUCTION. HYSTERESIS. In electricity, the hysteresis loop occurs when a metal is subjected to a varying magnetic field. Once you remove the metal from the magnetic field it is still loaded, so the act of made a charge and discharge cycle produces losses. Making a zero crossing detector circuit is actually very easy and it could be effectively applied for protecting sensitive electronic equipment against mains switch ON surges. A zero crossing detector circuit is mainly used for protecting electronic devices from switch ON surges by ensuring that during power switch ON the mains phase always "enters' the circuit at its first zero crossing point. So what is a zero crossing detector? We all know that our mains AC phase is made up of alternating sinusoidal voltage phases as shown below: In this alternating AC, the current can be seen alternating across the central zero line and across the top positive and bottom negative peak levels, through a particular phase angle. This phase angle can be seen rising and declining exponentially, meaning it is doing so in a gradually rising and gradually falling manner . The alternating cycle in an AC happens 50 times per second for 220V mains and 60 times per second for 120V mains inputs as set by the standard rules. This 50 cycle response is called 50 Hz frequency and the 60 Hz is called 60 Hz frequency for these mains outlets in our homes. Whenever we switch ON an appliance or an electronic device to the mains, it is subjected to a sudden entry of the AC phase, and if this entry
Image of page 2
point happens to be at the peak of the phase angle could imply maximum current being forced to the device at the switch ON point. Although, most devices will be ready for this and might be equipped with protection stages using resistors, or NTC or MOV, it is never recommended to subject them to such sudden unpredictable situations. To tackle such an issue, a zero crossing detector stage is used which ensures that whenever a gadget is switched ON with mains power, the zero crossing circuit waits until the AC phase cycle reaches the zero line, and at this point it switches ON the mains power to the gadget.
Image of page 3

Subscribe to view the full document.

Image of page 4

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes