Archive for the ‘555 Timer IC’ Category

PWM lamp dimmer using NE555

PWM lamp dimmer. A simple and efficient PWM lamp dimmer using timer IC NE555 is discussed in this article. Yesterdays linear regulator based dimmers can only attain a maximum efficiency  of 50% and are far inferior when compared to the PWM based dimmers which can hit well over 90% efficiency. Since less amount of power is wasted as heat, the switching elements of PWM dimmers require a smaller heat sink and this saves a lot of size and weight. In simple words, the most outstanding features of the PWM based lamp dimmers are high efficiency and low physical size. The…

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3 Great Books to Learn 555 Timer Circuits and Projects

Any one who is interested in electronics would have come across this IC – 555. It is the one component that is used in many wide range of applications. 555 Timer is used in 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. So it is essential that you should have a deeper understanding of 555 IC and how it is used in these applications.  The best way to learn about anything in this world is to – ‘get your hands wet’. You should read,understand and do things on…

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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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Voltage doubler circuit using NE555

Description. The circuit diagram of a very simple voltage doubler using NE555 timer is shown here. Here IC NE555 is wired as an astable mutivibrator operating at around 9KHz. The base of the two transistors (Q1 and Q2) is shorted and output of the astable multivibrator (pin 3) is connected to it. When the output of astable multivibrator is low, Q1 will be OFF and Q2 will be ON. The negative terminal of the capacitor C3 will be shorted to ground through T2 and it will be charged to the input supply voltage. When the output of the astable multi…

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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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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 as an Astable Multivibrator

An astable multivibrator, often called a free-running multivibrator, is a rectan­gular-wave generating cir­cuit. Unlike the monostable multivibrator, this circuit does not require any ex­ternal trigger to change the state of the output, hence the name free-running. Before going to make the circuit, make sure your 555 IC is working. For that go through the article: How to test a 555 IC for working An astable multivibrator can be produced by adding resistors and a capacitor to the basic timer IC, as illustrated in figure. The timing during which the output is either high or low is determined by the externally…

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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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