Questions tagged [oscillator]

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

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0answers
60 views

How does an op-amp work without proper power supply?

I have built a chua's circuit following this diagram: Source: Kennedy 92(pdf). The rectangle inside NR is and eight pin dual opamp. Then, I remove the 9V battery on the right. It is replaced by a ...
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2answers
72 views

Capacitance divider of Colpitts Oscillator

For the following Colpitts Oscillator, Why does employing the capacitance divider up-converts the source impedance of transistor by a factor of (1+C2/C1)2
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1answer
59 views

Calculating Rs Value for 32kHz Pierce-Gate Crystal Oscillator Circuit

Edit: My primary objective is to learn the mathematical model to compute the load resistor \$R_s\$ to satisfy a given crystal's drive level, not just fixing the one instance below. I'm building a ...
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1answer
46 views

Colpitts oscillator: how to reduce amplitude thermal drift?

I have built this circuit, supply ±12V: I am using a LM6172 amplifier. I have found the transfer function of the filter involved: \$H(j\omega)=\frac{1}{1 + \frac{R_3}{R_1} - L\omega^2(C_2+C_1\frac{...
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1answer
82 views

Simple frequency-tunable spark generator?

This may sound weird, but... I am attempting to design a steampunk / gothic horror-styled electric harpsichord, with sparkgaps as the sound source in the vein of musical Tesla coils. Unlike musical ...
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2answers
46 views

Colpitts / Clapp oscillator crystal drive level

simulate this circuit – Schematic created using CircuitLab As I understand this circuit has some initial gain at startup, then as the oscillation builds up gain goes to unity at some moment. ...
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36 views

Clapp Oscillator Oscillating Frequency Strongly Dependent on the Transistor

For temperature sensing purposes, I have been challenging myself to design a dual mode crystal oscillator operating at the frequencies 30MHz and 90MHz (fundamental tone and the third overtone, ...
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3answers
92 views

Colpitts oscillator : having trouble while respecting Barkhausen criterion, is this criterion insufficient there?

I'm trying to simulate a Colpitts oscillator. I've determined transfer function of the low-pass filter of this circuit: I reached this expression: \$H(j\omega)=\frac{1}{1-LC_2\omega^2+jR_3\omega(C_2+...
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66 views

Can I replace the transistor in this circuit (Esaki oscillator) with a Zener diode?

Can I replace the transistor in this circuit (Esaki oscillator) with a Zener diode?
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1answer
44 views

Fundamental CMOS astable multivibrator

So i need to perform analysis of simple astable multivibrator circuit shown in the following picture: These Vdd and GND are just the power rails of those CMOS inverters. Now, i need to perform ...
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37 views

Load capacitance of the crystal: what is the practical difference between devices?

There's a lot of info and guides on how to select and calculate load capacitors for the parallel resonant circuits. They all assume that people do already possess crystal, and know its CL. That CL ...
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55 views

PCB Layout - Ground Plane Clearance Around and Under Ceramic Resonator

We are using Murata's 4MHz Ceramic Resonator (CSTCR4M00G53-R0) in one of our designs and request help in PCB layout design around Ceramic Resonator. The below Murata's FAQs page suggests not to place ...
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1answer
29 views

How is Q for surface acoustic wave devices measured?

I do not have a good understanding of Q, the quality factor. I get the basic concept that it has to do with energy losses within a system, particularly oscillating systems like resonators. Higher Q ...
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3answers
104 views

JFET stabilised wien bridge component ratios

I find myself in need of a sine wave oscillator and have decided on the wien bridge. I have followed all the tutorials but have a few questions that do not seem to be answered elsewhere. Firstly, I ...
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1answer
32 views

What is the difference between residual phase noise and absolute phase noise?

Studying the characteristics of an oscillator with a phase noise analyzer, but I don't quite understand the difference between absolute and residual noise. Any help would be greatly appreciated
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3answers
53 views

VCO circuit Analysis

can you help me with the basic comprehension of this Voltage Controlled Oscillator scheme (it was used in a PLL)? I do not understand why there are two varactors instead of one, and the role of the ...
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55 views

Is the difference in trace lengths why my RTC isnt working?

I am using the PCF8523TS RTC with a 32.768 kHz Crystal. I have tested the smaller package which worked fine with the Adafruit module, but I can't seem to get it to work with the TS package. I either ...
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1answer
42 views

Quartz Crystal and Resonance Frequencies

Let's consider this equivalent electrical model of a crystal: The evaluation of its series self resonance frequency is quite simple: it is sufficient to impose that the reactance of L1 is equal and ...
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1answer
59 views

Transformer and MOSFET combination not working

I am working to understand the circuit of a vibrating needle used in factories to scratch a mark on a soft surface. Essentially, this circuit drives a MOSFET bridge which then drives a Transformer. ...
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51 views

Time period of output in relaxation oscillator circuit

I'm an electrical engineering student, and have spent the last 4 hours trying to figure out the time period of the output of the circuit below (in terms of the variables shown in the image). So far, ...
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1answer
62 views

PLL (Phase Locked Loop)

I find a bit of confusion on the web about the use of the PLL. Sometimes I read that, given a certain input signal, it is used to generate a signal whose frequency is N times that od the input one, ...
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1answer
86 views

How to design a contactless mechanical shaker [closed]

I am trying to design a circuit to make an inductor oscillate with high-current (around 50A) at a low frequency. The inductor will act as a high-powered electromagnet. Most designs I've worked/messed ...
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1answer
60 views

Sallen-Key Low Pass Oscillator

How to design a Sallen-key Low pass Oscillator that gives undamped oscillations? I've grounded the input of the Sallen-key low pass filter but still can't get any oscillation at the output. I've ...
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1answer
119 views

STM32F303: Clock sporadically dies away

The clock of my STM32F303CC (links to datasheet; for reference manual see here) sporadically dies away, resulting in highly decreased code execution speed (see picture below). I already replaced the ...
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1answer
84 views

Oscillator capacitors to VCC

I recently came across this circuit in which the oscillator capacitors are connected to VCC and not to GND. Researching I've read many comments stating that VCC and GND are at the same AC potential. ...
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31 views

Astable multivibrator inverter

I'm new to electronics and trying to make an astable multivibrator oscillator. The PSpice simulation doesn't work (it says netlist error when I place a mosfet or a diode) and I get a really low ...
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2answers
51 views

Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
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25 views

termination of a parallel wire differential transmission line as delay line on variable dielectric constant medium

Well this has quite a long title, lets explain the situation I'm currently working on the design of a sensor to measure the dielectric permittivity of a liquid medium, the idea is to use a ring ...
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0answers
46 views

Understanding a ZVS Oscillator in-depth

For a project I've been building, I've been using the (overused) ZVS oscillator that can be found online. So far it's been working great transferring power wirelessly, but I'm interested in ...
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1answer
71 views

Transistor differential wein bridge oscillator wrong frequency

So I have created the attached Wien bridge oscillator using a transistor differential amplifier, the Negative gain is controlled using a potentiometer, center tapped and yes I understand that in the ...
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0answers
47 views

Always starting LC colpitts oscillator

Is there a way to make an LC oscillator that works in most circumstances? Which is able to start up an keeps oscillating for a wide range of inductors? I'm asking this because I made a LC oscillator ...
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3answers
67 views

Quartz Crystal Electrical Model

I need some explanations about the electrical model of a Quartz. Everywhere I search the definition of quartz I find that it is a crystal that starts oscillating mechanically if it receives a ...
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1answer
26 views

How to use SYSTEMConfigPerformance on a MPLAB X project

I started a new project for a pic 32 (pic32mx470f512l) with MCC. And now i want to use the function SYSTEMConfigPerformance to optimize the performance of the pic. It happens that i'm not able to ...
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1answer
33 views

How do I find this value for the feedback fraction?

How exactly do I find this value for the feedback fraction Beta? Thank you. omega_0 here is the natural frequency calculated as omega_0 = 1/RC and s is the complex frequency.
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1answer
29 views

Plotting G(t) of an oscillator in Cadence

I have a cross-coupled NMOS-only oscillator that has its bias voltage changing so its transconductance is also changing over time. I want to plot its transconductance (G(t)=G0-gm/2) over time in ...
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2answers
53 views

External oscilator on stm32f030

I am not sure if I calculated R_ext right. I am planning to use this oscilator. According to the document the calculation for R_ext is: ...
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2answers
75 views

How to calculate instruction cycles on pic?

I want to know how much instruction cycles are each line of a program, is there a way to do that? It's important to me because i'm having a problem with the oscillator (or might be something else) ...
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1answer
49 views

What clock source is the oscillator connected at the OSC1 and OSC2 pins of a pic?

I'm connecting a Crystal SMD of 32 MHz to the OSC1 and OSC2 pins of a pic. When doing the configurations for the pic, inside <...
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3answers
93 views

Two crystals, one oscillator

I'm not having much luck searching this out. I need a circuit that will allow me to select which of two parallel resonant crystals is operating with a common on-chip gate oscillator. I vaguely ...
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2answers
71 views

Doubt about Phase Locked Loop

How is it possible that the Signal Output will have the same frequencies as the Reference Signal?\$f_1\$, Frequency of the Reference Signal;\$f_2\$, Frequency of the VCO. Let's assume that \$f_1>...
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100 views

Ring Oscillator on FPGA for TRNG

I am implementing a TRNG on an FPGA. This TRNG is based on jitter created by ring oscillator and I would like to know how to implement the given ring oscillator on FPGA so that jitter is generated. <...
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3answers
49 views

Could an external circuit with 74HC series IC reliably test a 24 MHz crystal?

I made a circuit where the microcontroller works. I made a duplicate of the same circuit with a working micro, but that circuit does not start and there is no smoke and the PCB is clean (no loose ...
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2answers
62 views

Identifying a LC oscillator circuit and solving resonance frequency

Could someone please identify what type of oscillator this is in the first stage. I'm not quite sure if it is a Colpitts or not and also could someone specify the resonance frequency calculation if it ...
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2answers
42 views

PSpice simulation of phase-shift oscillator doesn't work

I'm trying to simulate on PSpice a BJT-based phase shift oscillator, like in the following schematic: but when trying to measure the voltage on the node connecting R3 and R5 I only get DC voltage (...
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3answers
42 views

Interrupt generating circuit: 0 ~ +3.3 V

For the purpose of testing a MCU and it's interrupt handling I want to design a circuit to generate interrupts. Ideally I would use a relaxation oscillator, but my supply is constrained to 0V and +3....
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0answers
48 views

Sine wave generator using a triangle wave input

I'm covering oscillators in my class right now and in the foot notes of my professor's notes he says that there is a "dirty and cheap" trick to generating sine waves. I replicated the circuit below ...
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2answers
709 views

CPLD based Pierce oscillator

I want to make a clock generator for Altera EPM240T100C5N using the CPLD itself as a Pierce oscillator. This CPLD has Schmitt trigger inputs so I guess this should be possible. What I`m not sure about ...
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53 views

Simple amplitude modulation of a square wave oscillator

I'm in the process of creating a classwide project for an introduction to op-amp and transistors. My goal is to create a 49 keys synth that every students can contribute a small part, run test plan ...
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1answer
64 views

Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it. However sometimes it starts to oscillate at 25 MHz, ...
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1answer
500 views

Why are the capacitors necessary for a quartz crystal?

I read that it is recommended to connect 2 grounded capacitors to both ends of the quartz crystal. But that doesn't make any sense to me. Since capacitors have no resistance, wouldn't that make it so ...