555 Monostable and Astable Calculator

555 Calculator

This calculator evaluates the performance of the generic bipolar 555 timer chip in both monostable and astable modes. Please enter the component values you require in the spaces provided, then click on the button and the results will be displayed. As a rule of thumb, it is best to choose resistor values above 1K and below 1Meg.  Large electrolytics should be avoided in favour of large value R's to reduce power consumption and timing inaccuracies due to leakage.                                 R: R K M                                 C: uF nF pF T Output High (Seconds) =

555 Timer as Monostable Multivibrator

A monostable multivibrator (MMV) often called a one-shot multivibrator, is a pulse generator circuit in which the duration of the pulse is determined by the R-C network,connected externally to the 555 timer. In such a vibrator, one state of output is stable while the other is quasi-stable (unstable). For auto-triggering of output from quasi-stable state to stable state energy is stored by an externally connected capaci­tor C to a reference level. The time taken in storage determines the pulse width. The transition of output from stable state to quasi-stable state is accom­plished by external triggering. The schematic of a 555 timer in monostable mode of operation is shown in figure.

IC 555 BASIC PRINCIPLE & THEORY

IC 555

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

3. Basics of 555 Timer

4. Block Diagram

5. Working Principle

6. Download Data Sheet

1. Introduction

One of the most versatile linear ICs is the 555 timer which was first introduced in early 1970 by Signetic Corporation giving the name as SE/NE 555 timer. This IC is a  monolithic timing circuit that can produce accurate and highly stable time delays or oscillation. Like other commonly used op-amps, this IC is also very much reliable, easy to use and cheaper in cost. It has a variety of applications including monostable and astable multivibrators, dc-dc converters, digital logic probes, waveform generators, analog frequency meters and tachometers, temperature measurement and control devices, voltage regulators etc. The timer basically operates in one of the two modes either as a monostable (one-shot) multivibrator or as an astable (free-running) multivibrator.The SE 555 is designed for the operating temperature range from – 55°C to 125° while the NE 555 operates over a temperature range of 0° to 70°C. 

Police siren using Timer IC NE555 !!!!

Description :

Here is the circuit diagram of a police siren based on NE55 timer IC. The circuit uses two NE555 timers ICs and each of them are wired as astable multivibrators.The circuit can be powered from anything between 6 to 15V DC and is fairly loud.By connecting an additional power amplifier at the output you can further increase the loudness.

IC1 is wired as a slow astable multivibrator operating at around 20Hz @ 50% duty cycle and IC2 is wired as fast astable multivibrator operating at around 600Hz.The output of first astable mutivibrator is connected to the control voltage input (pin5) of IC2. This makes the output of IC2 modulated by the output frequency of IC1, giving a siren effect. In simple words, the output frequency of IC2 is controlled by the output of IC1.

Circuit Diagram :