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Questions tagged [oscillation]

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2
votes
3answers
330 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 ...
0
votes
2answers
84 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 ...
1
vote
1answer
79 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
votes
4answers
163 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
votes
1answer
40 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 ...
1
vote
2answers
116 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 ...
1
vote
1answer
87 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
votes
3answers
388 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 ...
0
votes
0answers
87 views

Strange parasitic oscillation

Hi, I am building the following circuit but I have encountered the following issue: when giving power to the circuit, I get at the transistor base ( and at the collector too) the strange oscillation (...
2
votes
1answer
74 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
vote
2answers
218 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
votes
2answers
75 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
votes
2answers
210 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 ...
0
votes
1answer
32 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
votes
1answer
63 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
votes
0answers
42 views

Wien-Robinson oscillation circuit, Output is 0, need to know why

I've tried to build a Wien-Robinson Oscillation circiut by CM2000, but the output voltage is 0. I fixed the resistance and capacitor value but it does not change. Please tell me what is wrong. I ...
0
votes
3answers
93 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 ...
3
votes
5answers
918 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 ...
0
votes
1answer
194 views

Why is my relay oscillating for over a half-second?

I'm building a circuit that can turn on a relay when the variable resistor cools down. Its operating principle is cooling down the variable resistor increases its resistance, causing the voltage at ...
2
votes
1answer
191 views

AC analysis of a oscillator

This question relates to my previous question. I am interested in deriving an analytical relationship for the oscillation frequency of this oscillator. As the first step, I have initiated the ...
-1
votes
1answer
157 views

How do i get this constant current circuit stable?

Im making a battery tester / discharger. For this i'm using a constant current circuit made with an opamp and a mosfet. I built and tested the circuit by itself with around 3-4A and it was stable. I ...
0
votes
2answers
120 views

How to DC bias the output of a Wien Bridge oscillator so that it oscillates about 2V?

I was wondering what a practical method of biasing the output would be so that it osicllates around 2V? I tried connecting an DC voltage source in parallel to the positive terminal but alas the output ...
0
votes
0answers
64 views

Astable multivibrator with capacitor on output

Can someone explain how does the capacitor on the collector of Q2 impact the output voltage from Q2's collector. I would like if someone could draw the signal output voltage in Q2's collector when Q2 ...
0
votes
2answers
124 views

Opamp Voltage Follower Oscilates

I am trying to measure voltage across a 0.1R shunt resistor. When i measure voltage between input1 and input2 with multimeter i can see 10 mili volts. When i connect input1 to a voltage follower in ...
1
vote
2answers
550 views

Op Amp Oscillation BPW34 Radiation detection

I have build the following circuit on a stripboard Now the problem is, even if I do not have the BPW34 diode attached my output shows a nice sqaure wave as you can see here But I have no idea where ...
0
votes
1answer
138 views

Wien Bridge Oscillator

So I built the Wien bridge oscillator without automatic gain control and I am using a preset to tune the circuit instead. My question is this, so when I reduce the gain of the op-amp to something ...
1
vote
2answers
46 views

Instant signal frequency change on amplifier

I was wondering what happens to an amplifier when the frequency is suddenly changed from (in my case) 2401 MHz to 2479 MHz. Would the amplifier somehow oscillate at the beginning or would it be steady?...
0
votes
0answers
72 views

self-quenched oscillator

I am trying to simulate a circuit which is composed of an oscillator which oscillates and reaches a maximum oscillation amplitude, then there's a peak detector that is following the peak of ...
1
vote
1answer
69 views

Negative-Gm Oscillator Biasing Conditions

I have some questions regarding the circuit below. I need to ensure two conditions are met. The output is taken from the drains of the cross-coupled pair. I think the drain voltages (1.198V) are not ...
0
votes
1answer
33 views

regions in cadence

I have a circuit that in it mosfets go through different regions (the circuits's core is an oscillator, I quench my oscillator by some mechanism and then let it oscillate again till the amplitude of ...
1
vote
1answer
81 views

Oscillation in digital circuits?

When designing analog circuits with feedback loops, attention must be paid to concepts such as gain and phase margin, open-loop gain, closed-loop gain, etc. in order to prevent oscillations (if you're ...
0
votes
1answer
72 views

Voltage regulator position

Hello if unregulated power supply (transformer, bridge and main caps) is 30 cm away from the circuit to feed, is it better to put the voltage regulator close to the circuit (long input and short ...
0
votes
0answers
184 views

Opamp + FET oscillate in voltage regulator for inductive load

I'm currently trying to regulate the voltage on an inductive load. The idea is to use an opamp to divide the actual voltage across the coil down, compare it to a set voltage and drive a FET so that ...
3
votes
2answers
116 views

Simple Constant Current Circuit Acting Strange on Occasion

I have a simple constant current source driven by a DAC. Very low frequency, less than 100 Hz changes on the input. I have had trouble once in a while when the transistor either fails or temporarily ...
1
vote
1answer
254 views

Some questions about a magnetically coupled circuit

Below the RLC circuit on the left side by the help of a periodic impulse generator V1 generates periodic damped oscillations with a certain frequency, and the resulting oscillating current couples to ...
1
vote
1answer
142 views

High freq OP-AMP voltage follower is ringing and is unstable

I try to design analog buffer for the 5MSPS STM32 ADC. I try to use TSH114IDT or CLC4007 opamps ( I need 8 in total). I have done so far: Tried the design below with or without some of the elements - ...
0
votes
1answer
156 views

How can I correct instability in a push-pull transistor amplifier?

In our EE lab, we had to build the following amplifier. It is from this lab manual, page 40. A week ago, I built it successfully, with 2n3904/3906 and d44vh10/ d45vh10 for the power amplifiers (Q3,...
1
vote
4answers
577 views

Problem with opamp stability in DC load

I'm trying to make DC load up to 20A with 1mA precision. Current sense resistor is 5mΩ, so the voltage on this current sense will be from 5μV to 100mV. I picked LTC2050HV (datasheet) which have very ...
0
votes
0answers
401 views

Design of a cross-coupled oscillator

I'm trying to simulate a cross-coupled oscillator as this: and considering Rp(gmp+gmn)>1 for the oscillation condition and using \$f_{osc}=\frac12 \pi \sqrt{LC}\$, to set the L and C. But my circuit ...
1
vote
0answers
135 views

Why does this resistor avoid this oscillation?

I am learning the effects of diodes going trough ON to OFF (so that I can see the consumption of these kind of power supplies) and, when it comes to simulate the circuit, I dont understand why if I ...
3
votes
1answer
564 views

Strange oscillations with TL431 voltage reference

I have a problem with TL431 voltage reference circuit: There is no load connected to VREF25. When I remove C8, voltage VREF25 is perfectly stable 2.5V. But when I put C8 back into the circuit, ...
8
votes
2answers
694 views

Is it possible for an opamp to oscillate at a frequency greater than its GBP?

I was installing a tl3141 into a headphone amplifier circuit and it appears to break into ~250mVp-p oscillation at 8-10MHz on the lower half of the waveform when fed a 1kHz sine wave. Is that even ...
1
vote
4answers
128 views

Capacitance on the output of an op amp

I have read a lot about capacitive loads on the output of an op-amp and the possibility of unwanted oscillations and instability. my knowledge on phase margin and frequency domain analysis is a little ...
2
votes
1answer
102 views

Optical isolator (VO0600T) circuit not working

I have a circuit where a 3.3 V DATA signal is optically isolated using the VO0600T IC. The circuit is as follows: In the schematic, VEE = 5 V (pin 8). Note that there are 2 separate grounds on either ...
3
votes
2answers
365 views

NE5532 strange oscillations

I am designing a small audio amp and am experiencing some weird oscillations in the first OPamp (NE5532), wich is setup as a noninverting amp. The amp is supplied with +-20V and has 100nf bypass ...
2
votes
0answers
385 views

Crystal Oscillator Design and “Crystal Drive Level”

I followed the video at the link http://www.analogzoo.com/2015/07/ . The video directs watchers to a tool at http://www.analogzoo.com/lab/pierce_bjt.html to help determine parameters to cause ...
15
votes
1answer
921 views

Where do the oscillations on the output voltage of my buck converter come from?

I am currently building a buck converter. Its main parameters are the following: 24V input 5V/3A output Able to sustain large load transient currents caused by the switching of power LEDs (~2A) I ...
0
votes
1answer
203 views

Cascaded op amp instability, oscillations

I'm trying to design simple voltage regulator with differential feedback. Vin = 12V Vout = 2-5V Iout = 0-7A In simulator I can see large oscillations. The larger the output current, the higher ...
0
votes
2answers
106 views

RC oscillator model in attiny microcontroller

I was reading in the datasheet for the attiny85 that the internal RC oscillator can be callibrated to run at different frequencies based on the value in the OSCCAL register. (Page 194 graph: RC ...
0
votes
0answers
35 views

Help with modelling a piezo

I'm using the Van Dyke model from this article and I'm a bit lost on a few things. Since the only nodes I can physically connect to are the ends, can I assume that I am limited to the voltage across ...