New answers tagged noise
2
It is a strange choice of opamp as a headphone amp.
20mA current limit might be ok into high Z cans, but will be a bit limiting into a big pair of over ear low Z cans, and it is far from being particularly quiet. Paralleling up a couple of 5532s thru suitable resistors seems likely to bother be quieter and cheaper.
Is your codec really ok driving into 500R? ...
2
Are you sure that you need 20x amplification?
In my experience, the line out voltage levels can actually be higher than what you get from "headphones out".
You can experiment with the output capacitor a little... not sure what bass response your headphones have, and your "line out" from the audio codec - but you can speculatively try ...
3
This is an inverting amplifier with a mid-band gain of \$\mathrm{A_v=-10k/500=-20V/V}\$. Since this is an inverting amplifier, beats may be heard a bit odd because the push of a beat turns into a pull (think of the movement of the speaker's outer cone).
C424-R2 pair brings a high-cut at \$\mathrm{f_c=(2\pi \ 10k\ 80p)^{-1}\approx199kHz}\$, which is way ...
0
Your noise can couple over two path into the signal. If the power source of the OP Amp is noisi and the Amp does not have enough PSRR (power supply ripple rejection) the noise on the supply will show in the signal. Or it can couple directly to the signal (specially if you are working with high impedance).
To reduce power supply ripple, place a LDO between ...
1
A 1 kΩ thermal noise with a bandwidth of 10 MHz at 27 °C produces an RMS value of 12.87 μV. At 100 Hz, the value is 0.04 μV i.e. over 300 times smaller. I can't explain your scope noise pictures but the numbers speak for themselves.
also why a diode is needed in general in series with an AC signal for
capacitor to smooth out AC into DC signals
The diode is ...
3
Just eyeballing the ripples on your sine: that is 40 ripples per period of your sine - that's the sampling rate.
You forgot to add a proper reconstruction filter, as Neil already pointed out in the comments. You'll want to fresh up your discrete signal theory on why you need that!
0
You might choose to use a JFET front end for a guitar amplifier in order to preserve the higher frequency artefacts from significant attenuation when running into an amplifier with impedance somewhat less than 1 Mohm but, for an electret microphone I see no point (given that it might be powered by a 1 kohm to 10 kohm resistor).
so it's pointless connect a ...
1
In this answer I'm assuming that the basic circuit is a flyback converter that regulates to produce a 5 volt DC output. A regular old-fashioned power transformer cannot be relied upon to produce a stable 5 volt output due to the transformer's input AC voltage changing and because of its inability to provide decent regulation against load current changes.
The ...
1
Considering your requirements, only, you need (as you say) a pulse generator, that is supplied from 230 Vac, and delivers up to 20 Apk, with a variable frequency from 2...500 kHz. You also mention using galvanically isolated output, which makes sense, since you're supplying from the mains. Since you also seem to favour a half-bridge, then a simple concept ...
0
Your computer's soundcard is unlikely to have an output impedance of greater than 100 ohms. More likely 30 ohms or less. Loading it with 64 ohms will only introduce a few dB of attenuation.
Unless you have some really rubbish cables, I doubt you have any problem there either.
It's likely that the high acoustic sensitivity of the amplifier is responsible. ...
1
The spectrum analyser is making choices for various things like resolution bandwidth, video bandwidth, number of averages, according to an algorithm decided by the people who specified the instrument firmware. This was to optimise their idea of the SNR/time tradeoff in each offset span.
You need to force the instrument to make your choice of those things if ...
0
You're worried about the switching noise from the bridge rectifier in a power supply I deduce.
2 simple suggestions.
1: Use 'fast' diodes in place of a standard recovery rectifier or a shottky rectifier (which doesn't store charge).
2: Add some diodes across each rectifier. Depending on the wattage of your power supply, anything between 22nF and 220nF with a ...
2
As Andy computed, there is a voltage divider action between the wall power wiring, and the probe tip.
Place a piece of flat metal under your probe, large enough to coerce the electric field flux_lines to arrive orthogonally to the metal surface.
Ground this piece of metal to the scope chassis (scopes usually have bare-metal terminals on the front panel for ...
9
Why and from where am I getting this unwanted 50mV peak to peak ripple
Start by thinking about 220 volts (if that is your AC supply running in your building). Because it runs in two wires where one is basically ground (0 volts), the net near-field voltage is 50% or 110 volts and that field disperses and reduces in value the further you are away from the ...
-1
Yes, an unfortunately common problem.
The Y caps are indeed the source of the buzz. I have even modelled their influence in the past, using circuit analysis software. Moving them around (placement) won't help, as it's not the issue.
Short answer, you're taking a risk with third party power supplies.
Some horrible things go on in SMPS's. The electrical 'noise'...
2
The maximum non_permanent_warping of a strain gauge is 1%.
And the maximum Vout_differential of a strain_gauge, safely, is 1% of VREF.
(From what I recall reading).
Thus you should plan on using Gain=100 (40dB) in the INA.
Power Supply Rejection will be a big deal.
Establish an error or noise budget. Assume 10 microvolt Peak error.
Allocate 1/3 of that for ...
0
The spikes were a result of the limited digital resolution of the accelerometer. The reason that there are no clear levels that indicate the resolution: an FIR filter was applied to the data before I collected it.
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