555 Timer Circuits and Projects

CircuitsToday is listing some simple 555 timer circuits that have already been published in our site before. To know about the basics of NE 555 along with the timer circuit schematic, click on the links below. We recommend 3 books on the basics of 555 timer IC, that can be bought online from our store. These books are from the author Forrest M Mims, whose electronics based books have sold more than a million copies, and are being followed in many renowned universities all over the world. Check out their reviews and buy them from our online store:- 3 Great Books…

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Police siren using NE555

Description. A lot of electronic circuits using NE555 timer IC are already published here and this is just another one.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…

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High voltage generator circuit

Description. First of all let me remind you that this circuit is a very dangerous one. The output voltage of this circuit is in Kilo volts and it can seriously injure you or kill you. Try this circuit only if you have enough experience dealing with high voltages. I have no responsibility on any hazards caused by the circuit. Be very careful. This is a humble request. The circuit given here has three sections namely oscillator, switching stage and a step up stage. The oscillator is build around a NE555 timer operating at 25 KHz. The output of the NE555…

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Op-Amp Comparator

In this post we will be discussing about the op-amp as a comparator.We have already discussed other applications of the op-amp in rectangular wave form generator circuits like astable (or free-running) multivibrators, monostable multivibrators (or one-shot) and bistable multivibrators (or flip-flops). To get a better understanding of operational amplifiers click here:- Operational Amplifiers (Op-amp)  Op-amp Comparator A comparator finds its importance in circuits where two voltage signals are to be compared and to be distinguished on which is stronger. A comparator is also an important circuit in the design of non-sinusoidal waveform generators as relaxation oscillators. In an op-amp with an open loop…

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F to V Converter

F to V Converter Circuit using LM555 Timer CircuitsToday.com has introduced an online store to buy books that provide the basics and applications of 555 timer IC. There are 3 books in store. You can buy them after reading our reviews. You can know more by clicking here:- 3 Great Books to Learn 555 Timer Circuits and Projects Description. Here is a very simple circuit diagram of a frequency to voltage (F to V) converter. Such a circuit finds numerous applications in projects like digital frequency meters, tachometers etc. The circuit is mainly based on a LM555 timer IC. The IC…

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555 Timer-Ramp Generator

Ramp Generator Circuit-using 555 Timer IC We know that if a capacitor is charged from a voltage source through a resistor, an exponential waveform is produced while charging of a capaci­tor from a constant current source produces a ramp. This is the idea behind the circuit. The circuit of a ramp generator using timer 555 is shown in figure. Here the resistor of previ­ous circuits is replaced by a PNP transistor that produces a constant charging current. Charging current produced by PNP constant current source is iC = Vcc-VE / RE where VE = R2 / (R1 + R2) *…

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555 Timer Oscillator

A voltage-controlled oscillator (VCO) using the timer 555 is shown in figure. The circuit is sometimes called a voltage-to-frequency converter because the output frequency can be changed by changing the input voltage. As discussed in previous blog posts, pin 5 terminal is voltage control terminal and its function is  to control the threshold and trigger levels. Normally, the control voltage is ++2/3VCC because of the internal voltage divider. However, an external voltage can be applied to this terminal directly or through a pot, as illustrated in figure, and by adjusting the pot, control voltage can be varied. Voltage across the timing capacitor…

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555 Timer as Monostable Multivibrator

Are you familiar with the basics and applications of the 555 timer IC? Are you looking for a book that provides all these basics? If so, CircuitsToday has started an online store from where you can buy books on 555 timer IC, which have been reviewed in detail. You can go through the reviews and buy them here:- 3 Great Books to Learn 555 Timer Circuits and Projects 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…

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555 Timer IC Working Principle

  Block Diagram of 555 timer IC:       Comparator 1 has a threshold input (pin 6) and a control input (pin 5). In most applications, the control input is not used, so that the control voltage equals +2/3 VCC. Output of this comparator is applied to set (S) input of the flip-flop. Whenever the threshold voltage exceeds the control voltage, comparator 1 will set the flip-flop and its output is high. A high output from the flip-flop saturates the discharge transistor and discharge the capacitor connected externally to pin 7. The complementary signal out of the flip-flop goes…

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555 Timer IC Block Diagram

  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…

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