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282 Threads found on Oscillating
I think your LNA is oscillating
A self-oscillating transistor is not necessarily achieving high efficiency, you need to watch the waveforms. There are many possible problems, e.g. the collector voltage might rise to high so that transistor breakdown occurs, the oscillation frequency could also jump to a higher mode.
I designed a SMPS with 12v and 1 amps output. When i connect a dc bulb of load 12v 10W. The smps output oscillates (turns on and off) frequently for some time and then the output goes stable. what causes this problem. The pwm ic used here is TNY 278PN and feedback circuit with optocoupler and TL431. How to overcome this? so that my smps output
As I understand it, the principle is to get two coils oscillating at the same (or nearly the same) high frequency. The coils are air-core. A metal core would interfere with the ability to detect metal. Bring metal close to one coil, which should alter its oscillating frequency. This creates a beat (difference) frequency between the oscillators. Th
Skip initial transient analysis is only useful and possibly needed for simulation of linear oscillators like LC or phaseshift. Relaxation oscillators like NE555 don't have a stable operation point and always start oscillating without specific means.
Did you use the recommended pcb design shown in the datasheet? If you made a different pcb design then the amplifier might be oscillating at a high frequency which will cause it to get very hot.
How can you regulate 40V with a maximum measurement range of 4.9*8 = 39.2 V? The code is implementing a hysteretic I controller which is potentially unstable, at least must show an oscillating output. Did you test it's operation with a lower set point, e.g. 20 or 30V? There should be limiting means to avoid OCR2 overflow.
Overshoot doesn't happen in a "simple low pass filter with just a resistor and capacitor" which has a pure exponential step response. You need a least a second order filter with complex pole pair, e.g. made by a capacitor, inductor and a resistor. It has an oscillating step response if the damping is low.
An application note "AAN-2 Driving Capacative Loads" states that as a bigger capacative load is driven by an opamp, the frequency response changes such that the output oscillates and increasing it beyond a certain point shall cause the output to become unstable. It does not give scope output. I want to understand for a square wave and a sine wav
Hi, i want to realize a fully digital closed loop pwm modulator for my class d amplifier but i've no idea on how to start with my design. Googling i've found sigma delta modulator and self-oscillating class d amplifier implemented in analog way (input+feedback -> integrator -> comparator -> flip-flop). At the moment the mosfets of my class d
Hi can anyone help me to make work the constant current circuit with TL494 Half bridge config , Constant Voltage is working , in constant current mode even the the ic can control the current the wave form is oscillating in sawtooth shape at 50hz to 100hz in some range like 0.5amps to 0.65 and 0.8 to 0.9 , other range is ok My SMPS is 100V
I should point out one thing.. Either your VNA calibration is not well done or your device is oscillating.
Before solving the scope issue, I have a feeling that the circuit is not oscillating in this configuration. I think something is wrong, or is missing from the schematic.
not interested in buying one already made. If you feel like experimenting, this is a simple method to turn 12VDC into 24VAC sinewaves. It combines: * full H-bridge * oscillating action through LC 2nd order butterworth configuration * automatic detection of resonant frequency * boosts supply voltage to a higher vol
Plotting the stability circles for the provided S-parameters of NE3210S01 can be seen that the transistor is potential unstable in 1GHz-7GHz frequency range. Making stable to use as an LNA perhaps is not a problem, but to make it stable and then to make it oscillating could be a
I am doing calculations on negative feedback oscillator. Here is some confusing part. If oscillation condition is met either at input or output port, then circuit is oscillating. I understand that. But when i calculate reflection coefficients for both cases, i get different matching networks. I thought that formula of Gout and Gin for both cases w
I Know a guy who built this exact circuit 35 years ago. His power supply works to this day. I got the schematic from him. Our layouts are different and I attribute this fact to mine oscillating and his not. All I know is that the circuit works. I visited him about a month ago and gave it a go. Flawless. Current limiting works great and stable. Bett
Hi, Do anyone know self oscillating rectifier?
how? because even though there are capacitors in your active filter, there is a non-zero DC gain of the circuit. WHEN the loop is locked, that DC gain is used to tune the VCO to keep it locked. The capacitors, to some extent, just help the loop from oscillating/ringing if a perturbation happens.
Sounds like you have build a nice oscillator with the segment or digit driver transistors. Long PCB traces are a prerequisite to make it oscillating. There's a problem in your circuit, not directly related to the "ringing" problem which should be fixed first. The npn transistor segment drivers are only partly turned on by the 3.3V base voltage. Sho
Hi, I'm trying to build a DC motor regulation circuit, however I'm having some trouble with getting my rotary encoder to work properly. I tested the encoder in a pretty simple manner: I hooked it up to my Arduino board, and monitored one of the encoder channels on my PC. The output of the channel was in a form of oscillating pulses while the encode
I am trying to simulate my PLL for the 3 different process corners. For the fast corner, I get a result as shown: 123279 Why is the Vcont (Control voltage driving the VCO) oscillating like this? It should lock at 40 Mhz or what could be the reason for the oscialltions? It works for the slow and typical corners b
The factory added input level pots to each channel of this stereo amp (a custom mod for the purchaser) when it was built years ago. Now one of the channels is oscillating. The oscillation affects the audio range and will vary somewhat in frequency and amplitude depending on the setting of the pot. I swapped pots between channels and all was well
Hi, I attached the schematic of a gated ring oscillator and its timing and phase diagram. Having had this figure I have two questions. First of all, can anybody describe the phase behavior of the gated ring oscillator? How does the oscillator start oscillating from the initial phase at the rising edge of input data? In fact I am interested
thermal effects in the transistor and varactor. Use a power transistor with a big flange, to get small thermal resistance, and just throttle it back like it was a small signal transistor. The varactor, decouple it as much as you can. Why not leave it all DC powered, but just snub the RF signal so it stops oscillating.
I'm learning HSPICE. When simulating a ring VCO, I can't get oscillating wave. It seems to be locked,but i'm sure the connection is right for the netlist is available on Cadence Spectre. Is there any issues. Thanks in advance.
Hello I have found this power pierce oscillator in an old magazine and I have tried it with sucess, using the 2n2166 which gave max output at 3.5W. I have also seen this circuit which is another type of oscillator that is used as a self oscillating mixer in receive mode. I was wondering is I c
For designed op-amp's enable circuit, step input results proper steady state output. But with pulse input, output is oscillating. Why so? Thanks.
Hey guys, Attached is the figure of a instumentation amplifier which I am trying to get to work. I am trying to amplify a 10MHz signal received by a 2uH center-tapped aircoil. Its running off a 9V battery and a reference voltage of 2.5 V (Vref) is generated by a general purpose op amp. Also an LDO provides a regulated 5V supply to the opamps (LM
The self-oscillating MOSFET inverter is a rather bad design, it's neither guranteed to oscillate at all nor to keep the transistor maximum ratings.
A bit simplified, the snubber capacitor is charged by a series circuit of resistor and leakage inductance. While R charging involves 0.5CV? losses, L charging is lossless (but oscillating). Varying the L/R ratio gives different fractions 0.5CV?.
AC supply probably has lots of 100Hz ripple. Measure it with no load and full load signal. Each power amp is probably oscillating above 100Khz causing overheating. If it gets hot with no load, put 2.7Ohm 0.47uF as indicated in specs or similar series snubber on each output to ground. If DC out is not matched at Vcc/2, offset the offending one wit
Some DROs not oscillating without metal plate placed above resonator. As i understand it is not frequency tuning (phase condition) problem, because moving resonator does not start oscillation. Although placing small metal piece above resonator instantly starts oscillation. What stands behind this? Less radiation because magnetic field lines stick t
I'm not suprised it doesn't work. The original circuit is self oscillating, L1 and L2 have to be on the same magnetic alignment and corectly orientated. In your circuit you: 1. overload the output of the micro because you omitted the base resistor in Q3 2. have the secondary coils connected to the base of Q1. It should either be the collector or t
You circuit must be unstable (oscillating)from feedback phase shift as 8.2v/11k is not the same as 0.3V/1k in output shared current. ... Edit.. What does scope say? And what is the total load ...caution wire capacitance and inductance in layout. 1k+1k? This is design does not bias FETs properly and seems poor in general. It may need AC load
Problem you have is when resistors are changed Ic current must not be changed. Resistor 1k can have so high resistance that 270ohm resistor is not needed. In this case temperature stability is lowest possible. Changing resistors you also change the gain and phase of amplifier which may stop oscillating. 10mA current of a divider is a bit high for Q
2SC4367 has a typical transit frequency of 1 GHz (min. 600 MHz), so you're lucky if the circuit is oscillating at 900 MHz at all. You all want to use transistor with GHz bandwidth instead. Apart from this point, what's the value of C2? Is your circuit layout suited for 900 MHz at all? If you connected an antenna, it's frequency dependent radi
What's your problem with the circuit, it's rather straightforward. 1. A self-oscillating flyback converter 2. A transistor to speed up switch-off operation The diode in parallel to the transistor is a zener (e.g. 12 V) that keeps the gate voltage constant over input voltage variations. From the options listed by xenos I would prefer the pho
Hello all I'm designing a Class E PA at 13.56MHz. I find that Freescale MRFE6VS25N, which can work from 1.8MHz to 2GHz, is very suitable for my design. However, the wide working bandwidth makes a new issue: Will the amplifier be oscillating due to the harmonics which are s
Is it oscillating with the brush motor? It may be that it is an underdamped oscillation near 75kHz with 5A current limit on ripple which can blow most caps except Polyester or Polyurethane film with low ESR. Since a 1R resistor is also in series to current limit these instabilities, the CAP ESR must be much less than 1R. THe driver is much lower
Since your x2 Op Amp has a bandwidth of around 1MHz driving a capacitive cable load plus termination, it could be oscillating and you are hearing the thermal noise in the output stage. Load the output with something like 0.1uF in series with 100 Ohms to ground ~ 50kHz Although the 220 Ohm series R ought to prevent this. So layout, decoupling e
an injection locked ring oscillator is NOT A PLL! so lets start there. how are u injecting the subharmonic? How are you removing the oscillating power? what are you doing to make the ring oscillator ONLY free run at the output frequency?
Hi, I have a PLL target running at 12.5GHz. Schematic top level works. Standalone post-layout VCO also works. But top level post-layout PLL simulation is not working. I've tried all the methods i can think of: 1. add initial condition at VCO outputs; 2. set max. step. 3. add a current pulse injection at one of VCO outputs; (4. i haven't tried
If I mount an oscillator in Orcad, as I know how often it is oscillating.
Stability is not considered in the band which is interested only, instead stability should be checked until fmax.Therefore, your LNA may work in the band but it may also oscillate somewhere at out of band. What type of pHEMT do you use ?? D-Type or E-Type ?? You LNA is probably oscillating somewhere but your don't know.I understand this from absolu
This isn't a very clever circuit - don't expect good results! I think the way it is supposed to work is Q1 is a weak oscillator, whether it oscillates or not depends on the setting of P1 and the coils proximity to something that might change it's inductance. If it starts oscillating, the signal it produces is rectified by the voltage doubler of D
An oscillator needs positive feedback. If it has only negative feedback then it is an amplifier, not an oscillator. The phase shift circuit in an oscillator has a certain amount of signal loss which must be made up by the gain of the circuit. A simulator does not know that noise is amplified and gets an oscillator to start oscillating. Then you mu
.....But from my circuit i think that pull up resistor (at output of opamp) make the output 4V while inputs are not given. Am I right ?? no. The comparator has an input offset voltage that could be positive, negative or zero so the output could be high or low or oscillating.
This are two cascaded first order filters which have real poles and can't show an oscillating step response by nature. Instead you'll want a second order filter with a complex pole pair. It can be implemented either as LC filter or as active filter with feedback. Some references are here You'll decide
All amplifers will contain contain noise in the bandwidth of the oscillator and even overtones of crystal oscillators. The harmonic with the highest gain will end up oscillating. Both input transients on power up and random noise contribute signal that gets filtered. In the case of a balanced oscillator with exactly unity loop gain at 0 or 360 de