PWM LED Dimmer/ Brightness Control by 555 Timer With Video Simulation

How to change the brightness of a LED? Whether led lights are dimmable? Is it possible to adjust the brightness of LEDs? LED is basically a diode, when the forward voltage exceeds 0.7 volt, it starts to glow, and if the forward voltage is less than 0.7 volt, it will be in the OFF state. What happens if we are providing a high voltage to the LED so as to increase the brightness?

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Binary Up Counter Circuit with working animation and simulation video

Here we are going to discuss about an Asynchronous 4 Bit Binary Up Counter, a circuit made up of several J-K flip-flops cascaded to generate four bits counting sequence. An up counter is basically a digital counting circuit which counts up in an incremental mode. Here we have given the simple counting circuit setup using 4 flip flops and a simulation video for better understanding.

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Low Pass Filter/Integrator Circuit Using Op amp 741

Here we are opening the door to a very wide range of useful and exciting application of the opamp. Here we are discussing an opamp RC circuit named as opamp integrator circuit. This circuit simply performs the integration of the input waveform.

The integrator output voltage Vo can be expressed as

                                                       where K is the constant of integration.

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Ring Counter Circuit Working Principle with Animation and Video

Digital counters have several applications in electronics circuits. Counters in digital electronics are used at different situations. Here we are going to deliver the idea of a Ring counter circuit, which is a register counter. Working animation and circuit simulation video of ring counter are also given along with this article. A ring counter is formed by feeding the output of a shift register to its own input.

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RC Phase Shift Oscillator Using Transistor (BJT): Circuit & Working

In this section we would like to introduce you a transistor oscillator circuit, called as RC Phase shift Oscillator. First of all we need to know what is an oscillator. An oscillator is an electronic circuit which acts as a sine wave generator. The only requirement of an oscillator is a DC power supply source. It is widely used in frequency variable signal generators, so it is a common basic electronic circuit.

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Voltage Regulator Using Zener Diode Circuit

Zener diode regulator is a basic electronic circuit which is very useful for those interested in hobby circuits. This circuit is used for obtaining a regulated voltage at the output which can be used for biasing other circuit elements. Now how to use zener diode as voltage regulator? When zener is in reverse breakdown region, the zener voltage remains almost constant irrespective of the current through it.

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Types of Diode Clipping circuits:Series clippers and Shunt clippers

Clipper circuits are one of the basic electronic circuits. Every time when we design some circuits, we will have to restrict or slice the input waveform for obtaining desired output. Almost all circuits require this kind of process. From the property of diodes, scientists found out that slicing or restriction of waveforms is possible. For that they used the most important property of diodes, ‘the unidirectional conductivity’ of diodes.

Such devices used to shape or slice waveforms are known as clipper circuits. It is also known as a slicer circuit. According to the output port (across which the output is taken), diode clipper circuit is classified into

• Shunt clipper
• Series clipper

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Full Wave bridge rectifier circuit with working explanation

What is a rectifier? A rectifier is an electronic circuit that converts AC voltage to DC voltage. It can be implemented using a capacitor diode combination. The unique property of diodes, permitting the current to flow in a single direction is utilized in here.

Now what is a bridge rectifier? Bridge rectifier is a full wave rectifier circuit using the combination of four diodes to form a bridge. It has the advantage that it converts both the half cycles of AC input into DC output. 

Rectifiers are one of the basic electronic circuits. If you are an electronic hobbyist then this tutorial will help you to get started with your lessons in electronic circuits. 

A good bridge rectifier power supply (rectifier applications) is essential to start your home electronics lab. Below is the full wave bridge rectifier schematic and operation explanation in detail.

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Zero Crossing Detector (ZCD): Comparator circuit using 741 op amp

Zero crossing detector(ZCD) is a voltage comparator that switches the output between +Vsat and –Vsat (Vsat: Saturation voltage almost equal to 14V) when the input crosses zero reference voltage. Then what is a comparator? In simple words comparators are basic operational amplifier circuits that compare two voltages simultaneously and switches the output according to the comparison. We can say zero crossing detection circuit is a comparator example. We will discuss in detail about comparator in our upcoming articles. Inverting zero cross detector circuit schematic using op amp 741 IC is shown below along with working, input output wave forms.

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Wein Bridge Oscillator using ic 741 op amp

Wien bridge oscillator is an audio frequency sine wave oscillator of high stability and simplicity. Before that let us see what is oscillator? An oscillator is a circuit that produces periodic electric signals such as  sine wave or square wave. The application of oscillator includes sine wave generator, local oscillator for synchronous receivers etc.

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High Current Transistor Switch for DC Motor Control Circuit

One of our previous articles explained about the working of transistor acts as switch, but that circuit was suitable only for logic level (to generate 0 or 1) and LED applications.  For applications with inductive loads (high current, high power) such as DC motors, relays we need another version of transistor switch circuit. Large current flow through the device is essential for power electronics applications. In this article we are going to explain about the basic working of transistor switching for inductive loads (relay, motor).This circuit is also called motor driver circuit or relay driver circuit if the motor in the below circuit diagram is replaced by a relay. We have also provided a small animation for better understanding of the working.

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Bridge rectifier regulated lab power supply circuit schematics

A good regulated AC to DC power supply circuit is essential for any electronic hobbyists and electronic students to do thier electronics hobby projects. Also a bridge rectifier power supply is one of the introductory circuits for beginners. Firstly we need to know what is a bridge rectifier? A rectifier circuit employs the conversion of AC voltage to DC voltage. Full wave bridge rectifiers have the benefit that they transfer both half cycle of AC input into DC output and also efficiency is two times greater than that of half wave rectifier. Bridge rectifier circuits are put into practice using diodes such as 1N4001, 1N4007 etc. 

• Transformer less AC to DC power supply
• Dual power supply using single battery source

Below is the circuit schematic of rectifier regulated power supply using 78XX voltage regulator IC. 78XX is a positive voltage regulator and available at different output voltages as 7805 for 5V, 7809 for 9V, 7815 for 15V etc. Hence you can implement power supplies for required voltages, that is 5V, 9V or 15V as you like. Solder this regulated power supply circuit on PCB and enclose it in a suitable case, definitely it will  help you for future circuit projects.

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Johnson digital counter circuit diagram using D flip flop 7474 (3 bit/4 bit) with animation/ simulation

The Johnson digital counter or Twisted Ring Counter is a synchronous shift register with feedback from the inverted output (Q’) of the last flip-flop. Q’ of the last flip flop is connected back to the input D of the first flip-flop. This inversion of Q before it is fed back to input D causes the counter to "count" in a special way. Animation/ simulation of this Johnson counter circuit is also given in this article.You can create simple dancing LED effects using this synchronous Johnson digital counter .The main benefit of this type of counter is that it only needs half the number of flip flops compared to that of standard ring counter to represent many states. So an n-stage Johnson counter givies a sequence of 2n different states and can therefore be treated as a "Mod 2n counter" whereas an n-stage ring counter has only n states that is "Mod n counter".

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Transistor act as a switch: DC Motor control (driver) circuit with animation

In one of the previous article we had already discussed about How transistor acts as switch? Here is another example of bipolar junction transistor BJT switching. In this case we will study a high voltage switching circuit i.e. how a transistor act as a switch for cutting flow of current when a high voltage flows. Today BJT switches are common in many electronic circuits and control systems. The main application of 'transistor act as a switch' is in the automation field.This example article explains how a transistor can control a DC motor. Animated working of transistor switch is also given for better understanding.

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Monostable 555 Multivibrator Working Principle and Circuit diagram with Animation

Monostable 555 timer multivibrator circuit (one shot monostable multivibrator) is a retriggerable mono shot pulse generator. The name ‘Mono stable’ indicates that it has only one stable state. The unstable state is called ‘Quasi stable state’. The duration of stable state or the pulse width is determined by the charging time constant of the RC network. We can transfer the multivibrator from stable state to quasi stable state by using  push button trigger switch. The animated (simulated) working of the mono stable 555 multivibrator is shown in this article. You can use our monostable 555 timer calculator tool to find the duration of pulse(width) easily.

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Pulse Width Modulation (PWM) generator circuit using 741 op amp comparator with output wave form

Pulse width modulation (PWM) is a method of changing the duration of a pulse with respect to the analog input. The duty cycle of a square wave is modulated to encode a specific analog signal level. This pulse width modulation tutorial gives you the basic principle of generation of a PWM signal. The PWM signal is digital because at any given instant of time, the full DC supply is either ON or OFF completely.

PWM method is commonly used for speed controlling of fans, motors, lights in varying intensities, pulse width modulation controller etc. These signals may also be used for approximate time-varying of analogue signals. Below you can see the pulse width modulation generator circuit diagram (pulse width modulator) using op amp. PWM is employed in a wide variety of applications, ranging from measurement and communications to power control and conversion. Pulse width modulation dc motor control is one of the popular circuits in Robotics.

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Summing amplifier/ Inverting adder circuit using op amp 741

Summing amplifier or an adder is used to sum two signal voltages. Voltage adder circuit is a simple circuit  that enables you to add several signals together. It has wide variety of applications in electronic circuits. For example, on a precision amplifier, you may need to add a small voltage to cancel the offset error of the op amp itself. An audio mixer is another good example of adding waveforms (sounds) together from different channels (vocals, instruments) before sending the combined signal to a recorder.

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Binary Amplitude Shift Keying (BASK) or On Off Keying (OOK) Practical Circuit using CD 4016

Binary Amplitude Shift Keying (BASK) or On Off Keying (OOK) is one of the digital modulation techniques in which the amplitude of carrier is switched according to the binary data. This digital modulation scheme is used to transmit digital data over optical fiber, point to point military communication applications, etc. Binary 1 is represented by a short pulse of light and binary 0 by the absence of light. Amplitude Shift Keying modulation and demodulation processes are relatively inexpensive and easy to implement. The main disadvantage of ASK is that it is sensitive to atmospheric noise, distortions and propagation conditions. Here is the practical circuit diagram of amplitude shift keying modulator using CD4016 IC. CD4016 is a switching IC with four embedded switches.

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Binary Phase Shift Keying (BPSK) modulation using CD4016 with Simulated output waveform

In binary phase shift keying (BPSK) modulation scheme, the phase of a carrier is changed in accordance with the digital pulse signals. BPSK modulator is basically a phase modulator. Here the transmitted signal is a sinusoid of fixed amplitude. It has one fixed phase when the data is at one level and when the data is at the other level, phase is shifted by 180 degree. Binary phase shift keying method has variety of applications in digital communications systems such as the wireless LAN standard, IEEE 802.11, digital modems, wireless telephone networks etc.

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Digital to analog converter using R 2R ladder network and 741 op amp with simulated output waveform

What is DAC? Digital to analog converter (DAC) is used to get analog voltage corresponding to an input digital data. Data in binary digital form can be converted to corresponding analog form by using a R-2R ladder (binary weighted resistor) network and a summing amplifier. It is more common and practical. Below is the circuit and output simulated waveform of R-2R ladder network DAC. This circuit also uses an op amp (741) summing amplifier circuit.

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