August 2011

Security alarm using IC 555

We know that when pin-4 is connected to positive potential, the IC works in normal condition, but whenever, the pin-4 is connected to ground, it overrides all functions of the IC and the output of the IC remains LOW. This facility is used in the following circuit to design a simple security system. Circuit diagram…

Filed Under: Bifocal Electronics

Simple Tutorials: Complete Working of NPN Transistor

Brief Introduction Transistor is a semiconductor device having three layers, three terminals and two junctions. Since we have only two types of semiconductors i.e. the p-type and n-type, there are two types of transistors: they are NPN transistor and PNP transistor. It is named as transistor which is an acronym of two terms: “transfer-of-resistor.” It…

Filed Under: Bifocal Electronics