Questions tagged [oscillation]

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1answer
27 views

L5973 (step down) used in constant current oscillates

For a couple of days i'am playing with a L5973 dc - dc converter whith I want to convert to a constant current driver for 5 or 10W LED's. It kind of works but I get some oscillations in audible range. ...
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3answers
61 views

Is it possible for any circuit to independently make its own trigger, sweep or oscillation without the aid of an AC sine wave?

Even a Schmidt trigger, attributed to being able to create the start of an oscillating circuit, has to get its start from an AC sine wave. It seems that no amount of tubes or transistors can ...
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1answer
68 views

How to understand this oscillating circuit made of two transistors and R C?

How to understand this oscillating circuit made of two transistors and R C? This is an oscillating circuit which is made of two transistors and some R C. As below schematic shows, during the power ...
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3answers
80 views

How does a transistor sweep generator work?

In particular I'm wondering about oscilloscope sweep generators, but the concept I don't understand remains the same for any type, which is, what does the triggering? I know a transistor can be ...
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1answer
30 views

Multicell overvoltage protection with op amps, how to get rid of oscillating behavior?

Still a beginner in analog electronics, so excuse me for being inaccurate. Also I am playing with circuitjs@falstad.com which might not be the most accurate sim... I wanted to provide a very sharp ...
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1answer
24 views

Bridge rectifier ripple under load

Why when I put even a light load on the bridge rectifier output shows 100Hz ripple? simulate this circuit – Schematic created using CircuitLab SR240 datasheet
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0answers
15 views

2 switch forward converter oscillation simulation

Here is the simulation of a 2 switches forward converter : The blue waveform is the voltage across the inductance. It seems that there is an RLC circuit. R is really low, which is why the ...
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1answer
67 views

Amplifying voltage from an inductor

I have a primary inductor connected to a voltage source with frequencies varying from 100kHz to 15MHz. This primary inductor induces a voltage across a secondary inductor via coupling and I want to ...
9
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4answers
2k views

The Intuition for RLC circuits

I'm reading through Hayt's Engineering Circuit Analysis 9e and it does a fairly good job of giving the intuition for "where" the energy is going in a damped RLC circuit, but I'm hoping that someone ...
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0answers
59 views

Finding Quartz Crystal Datasheets and Choosing resistors for Pierce Oscillators

I am trying to build a 2Hz oscillator using a CD4060 IC and a 32.768kHz quartz crystal for a digital clock project. The schematic below is from a hackersbench article. I've circled the part i'm ...
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2answers
77 views

How Does the Positive Feedback Bring an Oscillator's Poles on the Imaginary Axis?

In an oscillator, there is a positive feedback that injects energy into the system in order to sustain the oscillations. This feedback places the system's poles on the imaginary axis. I'd like to know ...
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1answer
51 views

Paralleling MOSFET Oscillation

I'm currently reading an application note about paralleling MOSFET and oscillation and it is written the following sentence : "In addition, parallel MOSFETs share a common low-impedance path, which ...
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1answer
32 views

Oscillations with paralleled MOSFET

I m actually reading a section of a book which talks about parralleling MOSFETs. The book talk about "Power supply design". There is a sub section which describes how to design the circuit layout. It ...
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1answer
250 views

Voltage levels of Microcontroller Oscillator Pins

I am using MPC5606S Microcontroller. I want to clear one concept and have a doubt. The Microcontroller using 8MHz crystal on the pins 27 (XTAL) and 29 (EXTAL) And a 32.768kHz RTC crystal between ...
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2answers
146 views

Guitar amp “motorboating” after upgrading op amps

I've been repairing an old (~1982) Fender solid-state guitar amp. While I had it apart I took the opportunity to replace some of the RC4558 op amps with NE5532's in DIP sockets I installed. It was ...
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0answers
66 views

Unstable current source when reaching a certain threshold in current draw

I’m currently building a system for automated testing of ECUs. It consists of an ECU with regulated loads connected to its power outputs. The other IO of the ECU is connected to an IO expansion card. ...
3
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1answer
124 views

Dave Jones's uCurrent - oscillations

uCurrent is a tool for measuring small (micro) currents by Dave Jones (EEVblog). He published source files: https://www.eevblog.com/projects/ucurrent/ I took his schematic and recreated in KiCad (no ...
3
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2answers
124 views

Where do the oscillations in a GaN half-bridge design exactly come from?

I'm working on a inverter pcb for a PMSM with GaN switches and I'm wondering: where exactly do the oscillations come from, when the high-side GaN goes high and the low-side GaN goes low. Why don't ...
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1answer
55 views

digital PLL - oscillations

I'm building a 3 phase digital PLL and implementing it on a microcontroller. I included a schematic of the SRF-PLL principle that I use. The abc->dq0 transform is done so that the q component for a ...
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1answer
98 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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2answers
70 views

How can I determine the cause of parasitic oscillation in a Teac A-R630 preamp stage?

The amp exhibits intermittent crackling noise, which I think is parasitic oscillation as it stops immediately I touch the base of Q409 with a scope probe or an insulated screwdriver. The amp will ...
4
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3answers
122 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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0answers
67 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
65 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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0answers
68 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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2answers
68 views

Oscillations on High Side Sensing Current Source

I designed a simple adjustable constant current source that uses high side sensing but I can't seem to figure out where the oscillations on my output are coming from. The circuit is shown in a picture ...
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2answers
115 views

What causes those oscillations in a comparator circuit

I designed a simple class D amplifier based on theory (output stage not pictured): Layout(ish, the board was modified in a few places, the whole top part is a separate PCB soldered into where some ...
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2answers
147 views

Load capacitance of crystal

I know this question has been asked many times before, however this question differs in the use of an uneven set of capacitors. I'm replacing the crystal on an old computer. The original symptoms ...
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0answers
228 views

LM358 Headphone Amplifier Oscillations

I'm trying to build a very simple headphone amplifier for my bass guitar. The bass has a built-in amplifier, meaning that unity-gain is sufficient for my amplifier, I essentially only need a voltage ...
0
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0answers
86 views

Oscillating boost converter output voltage that has a differential amplifier for load, in DRV8662 piezo actuator driver IC

I am building a circuit to drive a piezo stack in a pulsatile fashion and I am using the DRV8662 piezo driver from TI to do so. The circuit diagram is shown here (please disregard the several ...
3
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1answer
104 views

Active filter - oscillation and incorrect operation

I have a noisy and low amplitude (0-50mV amplitude) signal from a hall effect sensor (TI DRV5053) that has a ~1V DC offset. The signal will be in the range of 95-105 Hz and is used to determine the ...
0
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1answer
55 views

Trying to have NMOSs in parallel while passing current through only one at a time

If I wanted to have a bias current I1 going through M1 or M2 and I want M1 to alternate between on off (M1 on/M2 off, M1 off/M2 on) would this work? I simulated this with spice and for the first ...
0
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1answer
84 views

Can oscillations happen even if negative feedback is present?

By OPAMP book says that virtual short is applicable in OPAMP only if negative feedback is present an output is not oscillating.I don't get how oscillations can occur at output if the feedback is ...
12
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2answers
2k views

This op-amp buffer is oscillating and I can't figure out why

Currently, this is the only assembled part on the circuit board. This is a simple inverting buffer circuit that should be at the input. The op-amp (LTC6241HV) is powered +/-5V from a linear bench ...
2
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3answers
400 views

Opamp + NPN and MOSFET in the feedback network, how to prevent oscillations

Background The task is to add an electronic means to limit the power applied to an electric motor in an industrial setting. The operator normally controls the motor power through a lever that is ...
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2answers
127 views

Deliyannis-type narrowband filter is oscillating when I apply GND to the input

TLTR: My Deliyannis-type narrowband filter is oscillating when I apply GND to the input Vin. I was expecting to get almost zero volts, but I am actually getting a sine wave at almost 20KHz. I´m trying ...
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1answer
89 views

Simple way to create a disturbance on DC power

First of all, i must say that I am a software engineer, with very-low to no experience in circuits designs, and a very rudimentary understanding of electrical engineering and circuits. 101 really. ...
5
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4answers
1k views

Constant current source with MOSFET, OPAMP and Instrument Amp

UPDATE Based on the information from everyone answering below, I have modified my circuit and the oscillation has completely vanished! I started performing small modifications in order of easiest to ...
0
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1answer
69 views

LM2776 is it normal to have the oscillations in “bursts”

Is it normal LM2776 to oscillate in "bursts": The frequency of the oscillation is OK, but they come in the 8 oscillation bursts every ~9us. Is it normal? The board design and the schematic is ...
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2answers
353 views

PA92 OPAMP phase compensation

I'm having trouble to understand the phase compensation on the PA92 opamp. First I'll explain quickly the circuit I'm building.   1.  The circuit I'm using a 200V battery and would like ...
2
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1answer
114 views

Driving a difficult load with an Op-Amp: high capacitance, high current, high speed

I've been banging my head against this problem all day. I have a bizarre load that I need to drive over 88 feet of SMA that is a 68 ohm pullup to 15V. The cabling adds 2.64 nF of capacitance. I've ...
5
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3answers
615 views

Kickstarting an opamp for oscillating?

I have been building many different variations of op-amp oscillators but have come across a recurring issue that has manifested itself again in this VCO schematic: I find that when turning on my ...
3
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1answer
139 views

Quartz Clock Accuracy

Do the vibrations of aircraft engines (or any engine, for that matter) dilute the accuracy of a quartz clock? I haven't done any kind of research or hypothesis testing, though I believe that the ...
1
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2answers
979 views

Op amp driving a LED oscillates, how to stabilize?

I have a simple LED driver circuit like this: simulate this circuit – Schematic created using CircuitLab The op-amp is OPA354 250-MHz, Rail-to-Rail I/O, CMOS Operational Amplifier supplied ...
0
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2answers
136 views

Why exactly a RLC Circuit powered by DC oscillates?

First sorry if the question is stupid... I am learning. I am trying to visualize here, without equations, what happens to a RLC circuit that makes it oscillate. Consider a RLC circuit, a switch and ...
6
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2answers
539 views

5.5 kHz noise on SMPS output

I am designing a low noise SMPS like this http://www.ti.com/lit/df/tidrgc2/tidrgc2.pdf switching from 40-90 kHz. I have a weird problem, on the output we are seeing a spike of noise at 5.5 kHz and ...
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1answer
34 views

Can a bilateral switch block transmitter interference and can my board still produce great audio?

I made a circuit in which an ISD1760 chip outputs music via an LM386 IC and I like the quality and volume of sound, however, when I run an HM-TRP transmitter on the same circuit board and the ...
0
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1answer
83 views

High Frequency Excitation on Class D Amplifier

I'm building a discretized class D audio amplifier that's running at 250kHz that's designed to run on a single ended 80V supply. I was seeing very high amplitude, high frequency excitations on the ...
0
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3answers
133 views

LM2664 noise in the OPAMPS output signal. How to remove

I have 4 opamps powered from the LM2664. Two of them (1MHZ 1.6V R-R) are preparing the offset voltage for the pair of the OPA4141 which actually provide the signal for the ADC It works as expected ...
5
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4answers
2k views

How to calculate the frequency of oscillation of this low-pass phase shift oscillator?

In the following phase-shift oscillator a low pass network is used instead of a high-pass network. simulate this circuit – Schematic created using CircuitLab Usually the frequency of ...