New answers tagged noise
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will the following ground plane layout be valid for noise immunity/suppression?
No.
The quiet ground is essentially a plane for a few components as per the recommendation in the A3941 data sheet.
List the currents in your design, in descending di/dt order. On top of the list you'll probably find the input and output currents of your motor driver. Then, ...
0
Is your issue crosstalk between your motor drivers and low frequency microvolt signals you are processing on-board? If so, a gap isolating your most sensitive circuitry might be a good idea. Follow DKNguyen's advice: never route a trace across a gap, and gap any power planes the same way.
However, as tobalt notes, it is best to "let ground abound" ...
13
Generally gapping the ground plane is universally bad for EMI. Here is why:
If you fail to contain the generated energy at its source due to bad layout, it will spread throughout the board regardless of GND split or not. Use good layout, cabling and io-filtering. Minimize all loops.
the GND split will amplify radiated emission and pickup (slot antenna).
...
-1
For this PAM8610 PCB,
I recommend adding 'zobel network' for output stage.
For example, 0.22uF + 10ohm between L(+) and L(-) ,
R(+) and R(-).
Noise and parasitic oscillation will be reduced.
I had noise trouble for a long time.
Please kindly look at my blog;
https://takmiblog.tumblr.com/tagged/pam8610
2
I would recommend finding the schematics for this. Because it could be the speaker outputs. Attaching to the tape head circuit without modifying it might cause failure due to the line signal coming out of the phone is several times greater than the signal that is produced on a tape head. Also there are other things, like cassette present switch, actuated by ...
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These are comments, really, but I need to show you some pictures so I have to put them here as an answer.
Your schematic diagram doesn't seem to be correct. There are several points that don't make sense:
The MOSFETs don't appear to be connected to anything.
The drain goes to the transformer, but the source just snakes around and connects to the drain ...
1
It could be the RF module location near the heat sink.
It could be noise.
It could also be a noisy +3v3 power supply to the module, or heavy current from the stepper driver lifting the GND at the module, thus changing its logic threshold and/or latching it up or crashing its logic chip.
It's on a mezzanine connector, so you can try various approaches to do a ...
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Well... you really ought to move that radio far away from its current location, but I guess you already figured out as much :) I'm not convinced that these cheap radio modules have decent EMC characteristics to begin with though. The problems may be located on the RF module itself.
In the realm of desperate patches, here are various things you can attempt:
...
1
This is so different from my previous answer that it earns to be shown differently.
Removing noise in preamp is possible with complex processing - so complex that it's no more called mic preamp. In addition it's not perfect. To avoid artifacts to the recorded audio low noise amps and sensitive mics with low self-noise are used if possible.
But let's assume ...
4
I guess you have an electret mic which works like this:
I guess you built the preamp because you either tried the mic as is (some audio inputs allow it, they have the needed DC circuit) or you inserted a resistor, capacitor and DC voltage as shown in the datasheet, but the sensitivity was so low that to get acceptably high recording level one must shout if ...
1
One of these solutions may fix it, depending on missing details of “noise”
What is noise in engineering terms?
In AUDACITY open Analyze PLOT SPECTRUM after selecting an audio channel. Repeat for L & R channel
If noise in on R channel , may we assume this is your noise?
Use flexible small coax for all connections.
add 100 R + 10uF to power circuit and ...
1
The real reason might be just too slow signal at RCLK, or even on SCLK.
For example the TI 74HC595 has a maximum input transition rise or fall time of about 400ns at 6V or 500ns at 4.5V.
It means the signal may not spend more than the abovementioned time in the input threshold region between 0.5V and 1.5V, or there might be double clocking.
The RCLK will ...
2
The analog inputs of ADS1299 are rated from AVSS–0.3V to AVDD+0.3V. With AVDD at 5V this puts your 3V stimulation signal well within acceptable range.
Since you know where and when you apply stimulation, you can ignore that particular input at the moment.
This, of course, heavily depends on the design of the output stage of the stimulator, as inactive output ...
2
Switch Topology:
Specifically you need 8 times analog 2:1 MUXes. These 2:1 are also sometimes called SPDT switches. For single Pole double throw.
In contrast, getting 2 times 8:1 MUXes will limit your configuration options. It will not allow you to read or excite multiple pins at the same time.
Even more option are offered by 16 individual switches. Single ...
0
Not my idea at all but i believe you need a 5v-5v converter suited to isolating and/or converting DC power rails as per this video: https://youtu.be/n_b_0BWP0mI
2
I'm wondering if I could use an analog switch, to switch between the
two inputs.
Well, the ADS1299 uses a MUX (a type of analoge switch) internally: -
And that MUX interrupts the input lines to inject alternative signals so, the precedent is already set.
I'm not sure if an analog multiplex would work. I'm
worried about noise, since the signals are so ...
6
I have a noise output of 35nv / (sqroot (hz))
No, what you have is a noise spectral density. To convert that to a voltage you have to consider the bandwidth that is of interest to you. So, if the bandwidth of interest is (say) 100 kHz, then the noise voltage you get in a 100 kHz of bandwidth is this: -
$$35\text{ nV}\times \sqrt{100,000} = 11.07\text{ }\mu ...
2
This is already said at least twice by others. Here's my version of the refrain:
Signal needs 2 wires: The hot and the ground. You have several ground connections between the computer and the amp. The ground side signal current is distributed through all of them. The signal has no way to use the one and only wanted wire.
Unfortunately also the computer ...
3
My best guess is this: -
The DC-DC converter is producing common mode noise on its output power feed to the RaPi. That CM noise will be referenced to 0 volts on the amplifier power port and, the amplifier is unable to cope with that CM noise applied to its differential inputs. To prove this, if you grab hold of an audio transformer and feed the RaPi signal ...
2
If you use a PWM to output an analog value, its high level is the CPU's power supply voltage, and its low voltage is the CPU's ground. The former will fluctuate according to CPU power consumption and voltage regulator transient response. It is not possible to keep a voltage exactly constant on a load that draws randomly variable current.
When the Pi outputs ...
2
If +5 V and -5 V are regulated outputs of 1 or 2 DC/DC converters than I would use a CMF on the power supply input line.
If not, then you need two CMF. The first between +5 V and GND. The second between -5 V and GND.
If your design is committed to high production volume, then I suggest you to find a Taiwanese manufacturer and buy directly from them.
Cost of ...
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Why are there so few options for common mode chokes with three lines?
What is a good topology for this situation when using common mode
chokes with two lines?
Common mode chokes on two lines by their very nature cancel differential current MMFs from the load and therefore, can be made from much smaller ferrite components. How would these cancel with three ...
1
"What does it mean for the inverter (a digital circuit) to have low output impedance?"
Inverters has 2 output states:
Vout ≅ VDD (logic 1)
or
Vout ≅ GND (logic 0)
Hypothesis: Vout ≅ VDD
Attach a resistor R to Vout.
R will draw current out of Vout.
Low output impedance mean that you can lower R as much as you want (*) without Vout ...
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After looking at several different forms of transistor and general circuit noise, I accidentally discovered the answer was RF interference from my cell phone. I'm not sure which specific part signal it is, but I notice it more when my phone is sending and receiving text messages. My carrier is Verizon and phone Samsung, I don't have access to any others to ...
2
why ±10V is a common voltage range for commercial DAQ cards
It probably stems back from analogue op-amp circuits being powered from ±15 volt power sources. 10 volts peak would be a pretty normal undistorted or unclipped signal that could be produced from an op-amp on this power rail.
I think that using 10V instead of 1V on the output of the external
sensor ...
0
Make sure the models of your components are suitable for noise analysis, that is, they contain the appropriate noise sources.
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