Questions tagged [oscillator]

A device or circuit that generates an AC signal at a certain frequency.

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Can a GPS disciplined oscillator be better than its 1pps REFIN in stability?

GPSDO GPS disciplined oscillators provide good output stabilities when GPS is not locked thanks to oscillators (Rb, OCXO) in their structures. Holdover When GPS becomes unavailable, they also do ...
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Using resonators to phase-in a PWM

I'd like to have a constant PWM signals, much like this: Wherein the blue trace have centered it's hi at the 0 of the fully rectified AC & the red have centered ...
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How does a Colpitts oscillator work? Why is RFC used? [closed]

I want to know the initial flow of signal in this oscillator circuit. I got confused by the use of RFC and capacitor as RFC blocks the AC signals and allows only DC signal and a capacitor blocks the ...
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Trouble simulating a Pierce crystal oscillator circuit

I am trying to simulate a Pierce crystal oscillator on programs such as Falstad and LTspice. I have tried around eight different designs now and they seem unable to produce a sine wave in either ...
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LC circuit with back to back diodes [closed]

I know how an LC circuit works, but in this circuit there are 2 diodes and I am not able to intuitively get the waveforms of current and voltage across the capacitor. Could you please help understand ...
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My Wien bridge oscillator doesn't work, what could the problem be?

I suspect I am making a probe connection mistake, but couldn't figure it out. The circuit works fine in LTSpice but I don't get anything in a real experiment. What might be the problem?
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Is my summary of parasitic oscillation in op-amps wrong?

We were discussing negative feedback in op-amps with my community college instructor. I tried to learn ahead about the concept of parasitic oscillations in feedback circuits. I wrote a summary of what ...
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5 answers
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Effective way to generate low frequency square wave

My goal is to generate a 40Hz square wave in a reasonably cheap and effective manner with a precision around 1%. I considered two approaches: 555 chip: There it seems that they are themselves around ...
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Astable multivibrator small capacitor values

Is there a method to determine the values for the resistances? below shows when R1=R2 << R2=R3 and the capacitance is 10uF and the circuit works perfectly. However if I try to reduce the ...
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Wien-Bridge Oscillator

First question - Why does the Barkhausen Criterion state the total phase shift from input to output and back to input have to be zero? I thought the loop gain phase shift was supposed to be -180 for ...
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384 views

Why does this JFET buffer perform so poorly at 82 MHz?

I made a Colpitts oscillator that worked well first time. Frequency about 82 MHz. (nb. corrected diagram adding ground between series 68 pFcaps and corrected Vout) I wanted to add a buffer and chose ...
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Negative resistance - crystal

Why do we have the negative resistance concept in a crystal? How does the crystal exhibit negative resistance? I've read this Link and it seems to say that the amplifier is the one that causes the ...
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RCCR oscillator tuned with a single pot

I have incomplete details of a very interesting RCCR oscillator circuit that, back in 1960, used just 3 transistors as the amplifier. In those days, the transistors were germanium PNP, almost ...
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Crystals - Works on the principle of piezoelectricity or inverse piezoelectricity

I've done google search on the working principle of crystals and piezoelectricity. Nothing explains the actual principle. Is it piezoelectricity or inverse piezoelectricity? From what I've understood, ...
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Crystal oscillator - Gain

I was reading more about the crystal oscillators and had this question in mind. During the initial start up, the gain of the oscillator should be large and later on, the gain should be greater or ...
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Why can't we use crystal oscillators in series mode itself instead of parallel mode

I'm reading about the crystals and found that the crystal can be operated in series mode resonance as well as parallel mode resonance. In the case of series mode resonance, no external load capacitors ...
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Should the load capacitance value connected to the crystal be the same

I've seen many app notes and calculations that in the above circuit, the value of C1 and C2 are the same. I haven't seen in many places where the values of C1 and C2 can be different. Can someone tell ...
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Why does this oscillator circuit work well in the simulator, but not in the real implementation?

I want to build a 10MHz sine wave oscillator using a simple BC546 BJT. This is my schematic and its Multisim simulation: You can see I am getting around 10.5MHz quite well. When I build this circuit ...
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Is this two-tone oscillator a smart design?

I am fiddling a bit with building some kind of programmable sound generator using simple components. I got something more or less working now as a proof of concept: Here, the 555 is wired as an ...
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4 votes
2 answers
456 views

Generating a 1pps signal with ~0.1ppm accuracy

Firstly I just want to say I have next to 0 electronics knowledge so if I say something dumb I apologize. I am wanting to make a device which outputs a 1 pps square wave signal that is highly accurate ...
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How to derive effective transconductance versus oscillation amplitude in a oscillator?

In the page below in the lecture note shows a plot of effective transconductance versus oscillation amplitude. How is it derived? Or is there any source to derive effective transconductance versus ...
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Can this circuit with two resistors oscillate?

From this lecture note. Can this circuit oscillate as what the lecture said? I did simulate this circuit in LTspice but it doesn't work. The step from 1V to 0V does have many frequency components ...
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3 votes
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Simple Diode Mixer Help

Edit: Thank you for your input @Kevin White, much better results with 100 ohm injection resistors, a 1K resistor for a DC pathway and a 1K bias resistor from Anode to +5V. I am an RF enthusiast that ...
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External RC oscillator fuse programmed instead of external crystal fuse

Is there anyway to revive an Atmega8A? avrdude says avrdude: error: program enable: target doesn't answer. 1 ever since I ...
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3 answers
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Why don't simulators work with a self-oscillating voltage booster circuit using a transformer and a transistor?

simulate this circuit – Schematic created using CircuitLab I built this circuit (real not simulated.) With a 3V DC source, the output voltage is about 37V using a 1:14 transformer. I think this ...
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Where are the transistor number 18 and 21 in op amp 741 according to Wikipedia?

I was trying to implement this op amp from Wikipedia in Proteus : Like this: But I could not find Q number 18 and 21. What is the reason that there are not Q number 18 and 21? Or if this image is ...
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When should we switch from an internal FPGA oscillator to an external one?

I'm about to design a 5Mbps UART on a ICE40U0-5k and I've got a hunch I'll need an external oscillator when I spin my own board after I'm done with the dev board, but I would like to know how I can ...
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Relation between number of RC networks and phase shift in RC phase shift oscillator

The generalized expression for the frequency of oscillations produced by a RC phase-shift oscillator is given by the formula below $$f=\frac1{2\pi RC\sqrt{2N}}.$$ Here \$N\$ is the number of RC ...
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Which part of this transistor model op amp represents pin 5?

In this op amp oscillator pin 5 is connected to an RC circuit: I have a transistor model of that op amp and I want to connect an RC circuit to it like the above circuit: Since pin 4 and 8 represents ...
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Effects of too-frequent serrations in vertical sync pulse on analog horizontal deflection oscillator

Normal analog TV video signal has a vertical sync pulse with serrations to help keeping the horizontal oscillations in sync. Also, as I understand it, in case of an interlaced video, these serrations ...
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1 vote
1 answer
188 views

How can I build a current controlled 50% duty cycle oscillator from two CMOS inverters?

I am in need of a current controlled audio range (output around 1000 Hz) oscillator/multivibrator circuit. To make the result sound nice, I want to oscillator to have a 50% or near 50% duty cycle. ...
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How does a ring oscillator get voltage?

I am reading a book about digital design, and I came across the ring oscillator: What I do not understand is where does it get a voltage from if there is no input? How can it then oscillate?
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Using an oscillator instead of a crystal on W5500

I am designing a circuit I am planning to have fabricated that uses the W5500 Ethernet IC. I am quite new when with this and I've heard of a number of people having problems with the crystal (bad ...
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4 answers
101 views

Oscillator without active components

Is it possible to construct an oscillator using only passive components, including R, L, C, and transformers? No semiconductors or vacuum tubes, etc. Batteries are allowed.
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How to calculate the output impedance of an oscillator?

Is it possible to approximately calculate the output impedance of an oscillator if the rise/fall times at a given load capacitance are known, simply by using the formula for the RC time constant T = R ...
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How is energy conserved in an LC tank with voltage offset?

Consider an ideal LC tank oscillator offset by an ideal battery*: The core question is this: is the energy balance here maintained by the charge-voltage relationship of the battery? Energy seems to ...
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Blocking oscillator, Slayer exciter drawing too much power

I am trying to build one of these using an air-core coil. I got it oscillating but have to cut power off after 4 seconds as it starts to heat up (can't hold it with my fingers.) The transistor is not ...
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7 votes
3 answers
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Hartley oscillator not self-starting

I built a Hartley oscillator using an LM358 powered from a single rail of 5V. I used two identical inductors with inductance of 1 mH, a 0.01 uF capacitor, and 10k and 47k resistors for amplifier gain. ...
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1 answer
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SystemVerilog ring oscillator simulation with different delays

I am currently encountering issues with my ring oscillator simulation in SystemVerilog, which I cannot explain. Toolchain: ...
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2 answers
145 views

Square wave frequency multiplier

Where can I find a frequency multiplier circuit or IC that can multiply the frequency of a square wave or a sine wave by four? The input frequency can be from 100Hz to 1MHz, corresponding to an output ...
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Negative Oscillating Signal with Op-Amp?

I am trying to design a Wein Bridge oscillator that oscillates with frequency 1.5 kHz using LM741 Op-Amp. I simulate it in LT-Spice and obtained sinusoidal oscillation going both positive and negative....
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1 vote
4 answers
82 views

sensitivity and frequency-stability of capacitor-based oscillator circuit

I am constructing a capacitive transducer which changes capacitance as a function of changes in other physical properties. The capacitance is about 0.1~0.5 nF range, and I want to detect about 0.05% ...
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Shall I add bypass capacitors on Clock inputs?

I am designing my first high-frequency (7-9 MHz) circuit for my undergrad thesis. I am aware of the use and importance of bypass capacitors on the power inputs of my ICs and how (specially for HF) ...
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SiT1566 XTAL Wiring

I am looking to use this temperature compensated 32kHz crystal oscillator as the heartbeat of a quartz movement wristwatch. I want the superior accuracy and stability over any other oscillators, and ...
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What is the purpose of a negative feedback resistor in a schmitt trigger?

This schmitt trigger is used with an integrator to create a triangle/square wave oscillator but R5 has been added to the typical inverting schmitt trigger topology. I know that in simulation, this ...
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1 vote
1 answer
134 views

Oscillators-completely new approach

I found this link about high frequency VCOs. Although I don't work with such high frequencies, I gave it a try. So I designed this circuit: As you can see, I replaced BC547B (in previous post) ...
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Low voltage asymmetric duty cycle oscillator

I'm designing a low voltage (1.6 V and less) LED decoration. The source voltage is a low power, high impedance energy harvesting source. With the following characteristics: deliver between 0.8 and 3 V ...
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3 answers
118 views

Adressing timing issues on a pipelined logic circuit

Original title: How to modify the duty cycle of crystal oscillator? I have a 25.175 MHz crystal oscillator with a duty cycle of 50%. How can I reduce the waveform to a 25% duty cycle? It doesn't have ...
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203 views

Do you think this oscillator circuit will work if I build it in real life?

I managed to design this oscillator circuit. It works in the Multisim simulator. It doesn't want to oscillate in thr simulator if I decrease R6 resistor's value although it should have enough gain, ...
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32 kHz oscillator measurement

Thanks in advance for your help. I have the following circuit which is working fine. A 32 kHz oscillator NX3215SA (QUARZ SMD 32.768 kHz 3.2 x 1.5 mm) is simply connected to my MSP430F5438A on P7.0 and ...
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