Archive for the ‘Oscillators’ Category

FM Radio jammer

Description. Circuit shown here can be used to jam FM radios in its vicinity. The circuit is nothing but a classic single transistor oscillator operating in the VHF region. Working principle of the circuit is very simple and straight forward. Powerful VHF oscillations from the circuit will interfere with the FM signals to nullify it. Jammer circuits like this are illegal in many countries and you must assemble this circuit on your own responsibility. This circuit is intended only for fun and i request you not to misuse it. Circuit diagram. Notes. For L1 make 6 turns of 16AWG enamelled…

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Sweep Frequency Generator

Sweep-Frequency Generator The working of a sweep-frequency generator is explained in the article below. The working and block diagram of an electronically tuned sweep frequency generator and its different parameters are also explained. Related Article SIGNAL GENERATORS A sweep frequency generator is a type of signal generator that is used to generate a sinusoidal output. Such an output will have its frequency automatically varied or swept between two selected frequencies. One complete cycle of the frequency variation is called a sweep. depending on the design of a particular instrument, either linear or logarithmic variations can be introduced to the frequency…

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Signal Generators

Signal Generators In this article, the detailed explanation of a signal generator is given. The principles of signal modulation, the block diagram of an AM signal generator and the measures needed to achieve a stable frequency output is explained below. RELATED ARTICLE SWEEP FREQUENCY GENERATOR Like an oscillator, a signal generator is also a  source of sinusoidal signals. The main difference between a signal generator and an oscillator is that  a signal generator is capable of modulating its sinusoidal output signal with other signals. When signal generators are used for producing an unmodulated sinusoidal output they are said to be…

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Selection Of An Oscillator

RELATED ARTICLE VOLTAGE CONTROLLED OSCILLATOR (VCO) SWEEP-FREQUENCY GENERATOR BEAT FREQUENCY OSCILLATOR (BFO) WIEN BRIDGE OSCILLATOR PHASE SHIFT OSCILLATOR Here are the parameters that are to be noted while selecting an oscillator for a particular application. Frequency Range. The oscillator selected for a particular application should be ca­pable of supplying an output signal whose upper and lower frequency limits exceed those required by the application. Power and/or Voltage. The oscillator selected for a particular application should be capable of generating the pertinent quantity with a magnitude large enough to meet the requirement. Accuracy and Dial Resolution. The accuracy of an oscillator…

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Negative Resistance Oscillators

In this article, the working of a negative resistance oscillator is explained along with its types-dynatron and tunnel diode oscillator. The tunnel diode oscillator characteristics and circuit is also explained in detail. Related Articles VOLTAGE CONTROLLED OSCILLATOR (VCO) SWEEP-FREQUENCY GENERATOR BEAT FREQUENCY OSCILLATOR (BFO) WIEN BRIDGE OSCILLATOR PHASE SHIFT OSCILLATOR TRANSISTOR PHASE SHIFT OSCILLATOR Negative resistance oscillators make use of negative resistance elements such as tetrodes, tunnel diodes, uni junction transistors etc. There are two types of negative resistance oscillators, which are commonly used for high frequency generation. These are dynatron and tunnel diode oscil­lators. Dynatron operates in the negative…

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Beat Frequency Oscillator (BFO)

Beat Frequency Oscillator (BFO) Related Articles OSCILLATOR OPERATION TUNED BASE OSCILLATOR PHASE SHIFT OSCILLATOR COLPITTS OSCILLATOR Use the link OSCILLATORS to see all the articles including the working of oscillators, frequency stability, types and so on. The beat frequency oscillator (BFO) is used to produce a vari­able frequency output in the audio-frequency (AF) range. BFO is used  when the need comes to cover a very large frequency range with a single dial rotation as it can produce a very large frequency range with a single dial rotation. The block diagram of a beat-frequency oscillator (BFO) is shown in the figure…

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Wien Bridge Oscillator

It is one of the most popular type of oscillators used in audio and sub-audio frequency ranges (20 – 20 kHz). This type of oscillator is simple in design, compact in size, and remarkably stable in its frequency output. Furthermore, its output is relatively free from distortion and its fre­quency can be varied easily. However, the maximum frequency output of a typical Wien bridge oscillator is only about 1 MHz. This is also, in fact, a phase-shift oscillator. It employs two transistors, each producing a phase shift of 180°, and thus producing a total phase-shift of 360° or 0°. The…

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Transistor Phase Shift Oscillator

RC Phase shift oscillator. RC phase shift oscillator or simply RC oscillator is a type of oscillator where a simple RC network (resistor-capacitor) network is used for giving the required phase shift to the feedback signal. In LC oscillators like Hartley oscillator and Colpitts oscillator an LC network (inductor- capacitor network) is used for providing the necessary positive feedback. The main feature of an RC phase shift oscillator is the excellent frequency stability. The RC oscillator can output a pure sine wave on a wide range of loads. RC phase shift network. RC phase shift network is a simple resistor…

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Phase Shift Oscillator

  We select the so called phase shift oscillator  as a first example as it exemplifies very simply the principles set forth in the previous blog post. The circuit is drawn to show clearly the amplifier and feedback network. The circuit consists of a common source FET amplifier followed by a three section R-C phase shift network. The amplifier stage is self-biased with a capacitor bypassed source resistor Rs and a drain bias resistance RD. The output of the last section is supplied back to the gate. If the loading of the phase-shift network on the amplifier can be assumed to…

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Audio Oscillators

An introduction to Audio Oscillators also known as RC Oscillators So far, we have considered the oscillators which use L-C tuned circuit that causes a phase shift of 180° due to inductive or capacitive coupling in addition to a 180° phase shift produced by the transistor itself. The oscillators employing L-C elements, called the L-C oscillators, are very popular for generating high frequency oscillations but they cannot be employed for generation of low frequency oscillations as they become too bulky and expensive. R- C oscil­lators are commonly used for generating audio-frequencies as they provide good frequency stability and waveform. Also,…

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