Opto Coupler CTR Explanation

Opto coupler CTR explanation is not well elaborated by other authors and before I was also having hard time of understanding what is it. Current transfer ratio or commonly known as CTR is the ratio of the collector current to the forward current of an optocoupler. It is synonymous to a current gain of a bipolar junction transistor. If this is the first

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Designing MOSFET Switch – Comprehensive

MOSFET is not well discussed in the undergrads; much more how to designing MOSFET switch. MOSFET stands for metal oxide semiconductor field effect transistor. Actually it is easier than BJT if we are talking a switch circuit. Nowadays MOSFET is very popular in circuit designs. Such in automotive, power supply and general electronics as a low side and high side

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How to Analyze Optocoupler in Feedback System

One of the usual applications of optocoupler is to provide isolation between two ground reference. That is why it is often seen in power supply feedback circuit. How to analyze optocoupler in feedback system is to discussed in this article. Keep on reading below. How to analyze optocoupler in feedback system is not as difficult as you think. However, the lack

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How to Drive a Transistor into Hard Saturation

How to drive a transistor into hard saturation? In using a transistor to operate as a switch you must drive it into saturation. Saturation happens when the collector current cannot further increase despite there is base current increase. The saturation level of every transistor varies. The usual range is from 0.7V to ideally zero. For instance for a BC817-25 transistor,

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How Optocoupler Works

What is an Optocoupler? How Optocoupler works? These are just some of the questions I have before knowing this device. Opto coupler or opto isolator or photo coupler is an electronic device (a semiconductor) which is commonly used for signal isolation such as the primary and the secondary of a switching power supply. Its input circuit is a light source which is commonly a light

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BJT Operation Modes

BJT operation modes are at cut-off, saturation and active or linear. At cut-off, simply the BJT is not operating, say the base-emitter voltage requirement is not meet. The corresponding collector-emitter voltage is the same with the collector supply. At saturation the other hand, the BJT is driven into the point wherein its collector current can no longer increase despite of the increase

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