# Questions tagged [oscillation]

Oscillation refers to the repetitive variation of electrical signals.

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### Will a circuit oscillate at all its resonance modes or only the most dominant one?

Will a circuit oscillate at all its resonance modes or only the most dominant one? Consider an amplifier with a feedback loop that meets the Barkhausen criteria at multiple frequencies. Will it ...
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### Voltage Divider + Unity Buffer as a power supply

I'm working on an application where I need to step down a 3.7V LiPo down to a 1.0-1.5V for an embedded device that takes AAs (effectively an AA-to-LiPo conversion kit). In order for "low battery&...
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### What requirements of a feedback network are needed to produce oscillation?

I'm trying to understand how to analyze simple oscillators, and would like to know if my conclusions about the required feedback network are correct: The simplest way to build an oscillator is with: ...
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### Why does the LC oscillator work according to the scheme with a common base?

I study HF oscillators and i stuck. I put build the following circuit: The waveform: A question arises. Why does this work at all, because the input resistance of the circuit is extremely low. In ...
32 views

### Logisim latch oscillation issue

I would like to get familiar with latches, so I have build a circuit similar to an SR Latch. Logisim throws oscillation errors when I try to test it using different inputs. In my opinion the circuit ...
72 views

### What is the rule for continuous oscillation of an RF circuit with integrated LC?

Circuit simulation software helps out many times from hard mathematical formulas. I designed most of the RF circuits with the help of LTS and Proteus. I have seen that they are good equally, but have ...
28 views

### MOSFET drain current ringing in saturation region [duplicate]

I am testing below 500mA constant current sink circuit on test bench which turns on for 1 second and turns off for 7 seconds. During testing ,drain current oscillations of around 80mA were observed ...
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223 views

### How to control the amplitude of a Wien-bridge oscillator?

I am trying to design a Wien-bridge oscillator and understood the basic working principle of it. Now I got to the point where I want to add a system which would make the gain >3 during startup and &...
104 views

### investigating oscillation phenomena of a driver circuit

There is a driver circuit ,At first glance it amplified great the signal however when I probed R1 resistor as shown below on my lab scope with DC input , I saw oscillations. Now when I did step ...
1 vote
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### How can I remedy this audio amplifier oscillation issue?

I am trying to build this amplifier on a breadboard, but it starts to oscillate when I put my hand near the push pull transistors. What would cause this and how can I remedy it?
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### How to measure and sample oscillations in a LC tank using a Microcontroller

Since the oscillations in a LC tank starts with high amplitudes and dies gradually, and since the first oscillations are to some extent unpredictable in amplitude, how can one measure and sample such ...
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### How to determine if the feedback is positive or negative?

How to know if I have to apply the formula Af=A/(1-AB) [positive feedback] or Af=A/(1+AB) [negative feedback]?
1 vote
63 views

### Arc Lighter: Relationship between transformer inductance, oscillating frequency and energy of the spark

I'm building an arc lighter using YouTube videos as a reference. This circuit from GreatScott worked for me. I'm now trying to understand the relationship between the transformer inductance and ...
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### MOSFET does not fully turn off in flyback converter

I have this prototype flyback converter on a breadboard. However there is a problem. As you can see from the oscilloscope captures of Vds when I use Vin=25V the MOSFET turns off in 3 us. But in Vin=...
796 views

### Electromagnetic Pendulum Pulse Driver - Having Trouble Getting Circuit Running

Now I'm not super well versed in circuits though I've dabbled a bit in some circuit building in the past. I'm working on an electromagnetic driven pendulum for a clock I'm building. The Schematic I'm ...
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274 views

### Parasitic oscillation don't happen in an emitter follower

This is an emitter follower from "Learning the Art of Electronics" by Hayes and Horowitz (lab 9L.2): simulate this circuit – Schematic created using CircuitLab The autors claim that ...
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141 views

### How to dampen/reduce oscillations from crosstalk in encoder signals

I have two encoders that emit A/B signals for a total of 4 wires. Not sure if this will be relevant but these encoders are not the same and have different output impedances and rise/fall time. I also ...
1 vote
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### What kind of signal is at the grid of the triode in a VTTC?

Ok, so Adrian Marsh shows on his YouTube channel a VTTC with fractal fern discharges: https://www.youtube.com/watch?v=Oo_mINYLqOI It turns out to be a class C Armstrong oscillator, and Adrian has a ...
100 views

### MEMS Oscillator Simulation in LTSPICE

The MEMS oscillator topology i simulate is below fig1: Oscillator schematic Source: A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization Below is mine, the resonator i am ...
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### Instability as seen in time domain

It is my understanding that an unstable closed loop in a minimum-phase system occurs when the loop gain (A*B of the characteristic equation) encircles the -1 point on the Nyquist chart. In https://www....
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### Strange capacitor charge / discharge oscillations - SPICE

With this setup ngspice produces, for an 1ms dip-to-zero spike, this output Voltage source pwl(0 15 1m 15 2m 0 3m 0 4m 15 5m 15 2 15) r=0 If I make ...
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### How to suppress oscillations of the LC circuit current?

I have a following circuit which basically consists of three individual power electronics converters Converter_01 In case $v_1 > v_2$ it operates as a single phase diode bridge rectifier ...
• 1,113
1 vote
200 views

### Preventing Op Amp oscillation in PNP Linear Regulator Supply

I am currently designing a PNP-based linear regulator (see images). However, I am having trouble with it oscillating. There is a sizable 200 mV saw wave oscillation at its output. No, it's not power ...
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192 views

### Why it is oscillating? is this self oscillation? how to remove

Hello i have an circuit (2 stage op amplifier) with an resonance coil on input. I give an impulse on the coil and the circuit start resonating at frequency 1khz for seconds. How i can change the ...
114 views

### frequency-dependent network equivalent in time domain simulations

I have this question that has been haunting me for a while now. We all know that the first solution we think of when willing to account for frequency-dependent behavior in time-domain simulations, is ...
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### Amplification of the oscillation of a signal without amplifying the offset

Knowing that I only have op-amps, comparators, resistors, capacitors, and simple diodes at my disposal, is there a simple way to amplify the small oscillation of such a signal without amplifying the ...
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1 vote
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### How to calculate the capacitance needed to reduce oscillations in this circuit?

The following circuit is part of a DC current driver for a Helmholtz coil (L2,RL2), the circuits for Vreg and Vin work as intended so I am pretty sure that the oscillation is coming from this side of ...
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### Electrical motor/generator to represent variable spring damper system

I would like to build a system that represents a rotational double mass spring damper system with one set of spring and damper being represented by an electrical system. See image. The first mass (J1) ...
185 views

### Self-oscillating switching current limiter

I have a first draft design for a self-oscillating switching current regulator. It appears to work in simulation, but I would like to know if there are any concerns about this design that might show ...
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### High Frequency Oscillations on Mosfet Gate

I am working on a circuit that drives an inductor at its resonant frequency. However certain models of MOSFET I simulate the circuit with experience oscillations at the MOSFET gates as pictured below. ...
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1 vote
592 views

### Causes of parasitic oscillation in voltage amp with AN7062 IC

I'm having difficulty identifying the cause of parasitic oscillation that manifests at the output of this amplifier circuit, based on now-obsolete AN7062N. For context, this is the first amp level ...
1 vote
78 views

### AC Current Sensing LED indicator circuit

I'm playing around with a circuit to drive a LED based on the output from a current sensing transformer. The idea is to have the LED appear proportionally brighter with the output from the current ...
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### Phase shift oscillator

I arranged an RC phase shift oscillator with an LM324 op amp in a buffered mode using all the amplifier of the quad op amp. I set the gain to be 8.33 using Rf as 1 MΩ and Rin as 120k. 3 stage RC ...
106 views

### Baseline change in RF amplifier after peak

I have made an RF amplifier based on the MiniCircuits PSA4-5043+. The circuit is very similar to the one in the evaluation board by MiniCircuits. The layout was changed a bit but not much, and I am ...
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198 views

### High-voltage power source oscillations

I'm trying to make a capacitor leakage tester and capacitor reformer. I need to create a variable high-voltage power supply for that first. It can provide 0-500 V DC, current limited to 10-15 mA. It ...
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### Problem with output oscillation of voltage regulator

I am somewhat new to electronics and am trying to get the output of an LM350T_NOPB voltage regulator to have less than 50mV line noise at all loads <= 3A. Please refer to the schematic, ...
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2k views

### Why is this op-amp circuit oscillating?

The 40 dB gain op-amp circuit below oscillates (rail to rail) at around 140 kHz when there is no signal generator driving Vin. With a signal generator driving Vin at 10 mVpp it's fine with signals 15 ...
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### Is it possible to combat SR Latch oscillation or there are better alternatives?

I need to store a bit value and then ignore any attempts to store/change it again until it's reset by another signal. So I figured the SR Latch is suited for the task. However in my project there is a ...
1 vote
94 views

### DCDC booster oscillation because of small drops of input voltage

I'm stuck with this DCDC booster design that shows a bad oscillation output when a little voltage drop is present at the input. I have already tried to change the inductance to 4.7uH (actually, the ...
203 views

### DC stability issue with this audio amplifier

This design has a stability issue. The DC output point (without input signal) should be 0 V with a small offset, but it's not the case, because this point is not stable. Initially the amplifier had an ...
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### ZL30251 phase aligned

I just want to confirm whether the part zl30251 has phase aligned outputs? If not, can it be aligned? Also, I can confirm that both the outputs are LVCMOS. Can you please help me with this? Also, i ...
159 views

### Persistent op-amp oscillations only with oscilloscope

I'm currently debugging a high-speed amplifier circuit that seems to oscillate every time I connect an oscilloscope probe to it. Below is a schematic: I started by populating the circuit up to the ...
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### Why is this circuit not triggered (astable multivibrator) although it can be triggered on a breadboard?

Why is this astable multivibrator circuit getting balanced in a flash and not oscillating? It works on a breadboard. It once worked fine in simulation, but one day it stopped oscillating in simulation....
432 views

### 4th-order Butterworth filter - strange oscillation in output

I have created a 4th-order filter based on the result of calculations and simulation. Bellow is schematic: In simulation the filter works fine (I also checked the transfer function using this online ...
1 vote
168 views

### LED works but speaker does not work in multivibration circuit

This circuit oscillates with LED (in multisim 14). This circuit does not oscillate with speaker (labview, in real breadboard it only beeps twice and becomes silent, playback time 10 s, sample ...
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### How can I improve my 20m transceiver microphone amplifier?

After weeks (on and off admittedly) of debugging, I finally figured out why my homebrew 20m transceiver was oscillating on transmit. Despite all attempts to improve grounding (I have a single copper ...
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### Circuit for producing logic high when input is oscillating

I want to make a circuit which produces a logic high signal upon receiving an oscillating input voltage. In the past I have gotten away using an RC delay signal. When my input signal wasn't ...
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131 views

### Square wave oscillator

I built a square wave generator using an astable multivibrator circuit. With RB1 = RB2 = 100 kΩ C1 = C2 = 1 μ F my frequency is approximately 7.14 Hz. Is there any possibility to improve my circuit ...
74 views

### H-bridge amplifier DC oscillations

I have designed a simple amplifier (maybe too simple) that has bad DC oscillation (instability). I attach a picture with the schematic. It's not the entire amplifier but only the final stage, where DC ...
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