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197 Threads found on edaboard.com: Noise Feedback
Hi everybody, I am looking for filter for my power supply input. Power supply is a 220VAC 50Hz to 24VDC converter. However, a very powerful noise nearly at 10kHz is coming from AC and this noise leaks into my analog circuits. Every circuit has its own low noise regulators, but still i can't get rid of 10kHz and it's harmonics. :-( . (...)
flicker noise is a relatively low frequency effect that "upconverts" to the RF region. So if you can lower the flicker noise of the device itself, you will have less clock jitter. Some sort of audio frequency feedback loop to bias your oscialator transistor, keeping fets outside of their voltage range extremes, applying analog (...)
Hi, I am trying to measure AC rms voltage using PIC microcontroller. I have attached the circuit for measurement. I am connecting a 3V step down transformer out to the input of the circuit.The feedback capacitor has been added to reduce the noise, but I am getting noise if I add this. This is getting smooth after the low pass filtering. (...)
did you try to reverse the speaker polarity? If feedback is in phase at >unity gain, it will cause oscillation or howling. IF phase shifts 180 deg, at different f, but at a higher feedback, then a quality factor of non-linear response as AG indicated is your problem. Generally cheap mic's have background noise cancellation by having a (...)
As the figure shows, do the noise simulation, but the output and negative input node of the amplifier is not "directly" biased, how to get the input referred noise data from simulation? Thanks 129361
Higher OSR results lower quatization noise level at feedback. So effect due to ELD can be alleviated. See pp.213-215 of the following. BTW, it seems that 2nd edition of this book is published this year. Hi pancho_hideboo: Thanks a lot! D
Why are you talking about a very old uncompensated opamp? I have never seen a uA709 uncompensated opamp designed 51 years ago. Without a compensation capacitor added then it oscillates if negative feedback is used and its own noise starts the oscillation. Today almost all available opamps are compensated. Today you can still find an NE5534 partial
The L21 & C23 forms a post filter to reduce ripple / noise on the output this is typical in flyback designs & very difficult to compensate most of the times, refer attached PDF for detailed analysis
R5, C1 and C6 are there to filter out any noise from the supply line. C6 is needed because elcos aren't very good at RF. The purpose of C6 is to ground the RF currents in the tank circuit, necessary for the feedback that makes the circuit oscillate. If you don't want to make a tap in the tank coil you can use the capacitive coupling in the first c
Hello, Fig2 ,Page 7 of the attached DER-275 document shows a 3n3 capacitor (C14) across the lower feedback divider resistor of an SMPS. (Page 9 of this document says that this capacitor is there because of noise getting injected into the TL431 reference pin.) Do you agree that this capacitor should not be there? The way to address that (...)
Hi everyone, I am a super novice at this stuff, but I have made a "sound system". A speaker unit with 3 channels, which can listen to the 3 channels simoutanously or by demand. On the microphone unit you can setup the channels. I want to reduce the "background" noise / noise from the amplifier. There are way too much noise, when all 3 (...)
Remove positive feedback and bias Vin(+) with 1 or 2 diodes with pullup to Vcc. or R ratio. For RS232 the threshold is between this but close to 2 diode drops or 1.3V It depends on slew rate of Vcc and noise level and resolution of short bursts you may want to stretch.
Same as a crystal (which is a specific sort of resonator). It passes a particular frequency and in a feedback loop with an active amplifier, creates oscillation. There is no such thing as pure DC. Always some noise to start the process, unless you're at absolute zero.
Why not use audio port and Audacity free s/w to generate any audio signal.? Any standard shape + noise, or harmonic filtered or .... With spectrum analysis in feedback thru aux in recorded. OP asked to control an arbitrary waveform generator, not generate audio signals; those are two quite different functions.
Hi all, i am trying to measure AC mains using the DL-PT202D, witch doesn't have a useful datasheet. From the figures with op-amp below i can understand that that is a current to voltage converter. Using lm741 op-amp i can't make it work.. on the output of the op-amp i am taking only noise.. Has someone used it to drive me..? the topology with the
While designing low noise amplifier (LNA), we are using both passive feedback and active feedback. what are its importance and limitations of active and passive feedback, while designing LNA Passive feedback means we are using R,L, C as the feedback elements in LNA Active (...)
Will your 200k resistor breakdown when it has voltage peaks of 325V or more? There is no filtering so the transistor will conduct with fairly low levels of noise on the AC line. Since the opto-coupler uses the transistor as an emitter-follower then its maximum output is only +3.3V - 0.7V= +2.6V. Is this high enough?
The feedback pin will servo to a certain internal reference value, usually 1.23V or 0.8V for low voltage types. Wat you could do is to compare the a third of the LDO output (10 / 3 = 3.33...) to the DAC output with an opamp comparator, and then send this signal to the feedback pin instead. A low noise, rail to rail opamp like the LMV321 is (...)
There is nothing wrong with using Bottom rail for CM & DM reference; that is what it is designed to work with on this chip, but there may be CMRR penalties for noise below ground. The use of ground on both sides of transformer and then use an optoisolator is wrong. The bigger problem could be your lack of requirement specs for all PSU designs.
I am working on three phase v/f sclar drive and using semikron skyper32r IGBT driver. The drive work fine and motor speed is controlling as desire. But I also measuring input voltage and current form rectifier (dc output), before feeding it to IGBT. And here the problem come, there is high frequency noise in ground plan. the opamp circuit I use eff