Electronic Circuits and Diagram-Electronics Projects and Design

  Block diagram for the 555 timer is given in figure. As shown in the block diagram, a 555 timer consists of two comparators (simply op-amps), an R-S flip-flop, two transistors and a resistive network Resistive network consists of three equal resistors and acts as a voltage divider. Comparator 1 compares threshold voltage with a reference voltage + 2/3 VCC volts. Comparator 2 compares the trigger voltage with a reference voltage + 1/3 VCC volts. Output of both the comparators is supplied to the flip-flop. Flip-flop assumes its state according to the output of the two compa­rators. One of the…

The 555 timer combines a relaxation oscillator, two comparators, an R-S flip-flop, and a discharge capacitor.   R-S Flip-Flop. A pair of cross-coupled transistors is shown in figure. Each collector drives the opposite base through resistance RB. In such circuit one transistor is saturated while the other is cut-off. For instance, if transistor Q1 is saturated, its collector voltage is almost zero. So there is no base drive for transistor Q2 and it goes into cut-off and its collector voltage approaches + VCC. This high voltage produces enough base current to keep transistor Q1 in saturation. On the other hand…

The 555 Timer IC is available as an 8-pin metal can, an 8-pin mini DIP (dual-in-package) or a 14-pin DIP. This IC consists of 23 transistors, 2 diodes and 16 resistors. The explanation of terminals coming out of the 555 timer IC is as follows. The pin number used in the following discussion refers to the 8-pin DIP and 8-pin metal can packages.   Pin 1: Grounded Terminal. All the voltages are meas­ured with respect to this terminal. Pin 2: Trigger Terminal. This pin is an inverting input to a comparator that is responsible for transition of flip-flop from set…

A complete basic tutorial of 555 Timer IC. This article covers every basic aspect of 555 Timer IC. You may already know that SE/NE 555 is a Timer IC introduced by Signetics corporation in 1970′s. In this article we cover the following information about 555 Timer IC. 1. Introduction to 555 Timer IC 2. 555 Timer IC Pin Configuration 3. Basics of 555 Timer 4. Block Diagram 5. Working Principle 6. Download Data Sheet 1. Introduction 555 timer IC One of the most versatile linear ICs is the 555 timer which was first introduced in early 1970 by Signetic Corporation…