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10 dBuV EMI noise suppression from 0.8 to 1.8 MHz

Even the rectifier may be a problem. Use ultra-fast diodes for the diode bridge. Regular "good old rectifiers" are a pit of despair when it comes to EMI. It might sound counter-intuitive: ...
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How to lessen emission of an enclosure box from I/O ports?

To see what connector types are possible, you need to specify the voltages, currents, and frequencies of the signals. For example, fully shielded D-sub connectors are a standard item, but they will ...
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How to lessen emission of an enclosure box from I/O ports?

Even when considering I/O only, it is a very dependent question. In general: provide filters for I/O when going through the enclosure. Series impedance (R or bead) and if possible C to chassis. Just ...
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9 votes

Is twisting a single ended signal with its own GND really useful?

It strongly helps when done right. Allow me to make a small story arc to explain my answer. The problem Ground planes are good dump-and-forget nodes for return currents at both high and low frequency ...
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6 votes

Is twisting a single ended signal with its own GND really useful?

We can distinguish two kinds of coupling, inductive and capacitative. Using balanced twisted pairs helps reduce inductive coupling. But the question is about unbalanced twisted pairs. It turns out ...
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19 votes

Is twisting a single ended signal with its own GND really useful?

Yes, it is better. Model the cable as two transmission lines: one representing the differential mode (signal to GND wire), stacked on top of one representing the common mode (GND wire over GND plane)....
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6 votes

How does this modulation cause sidebands?

@Andy aka, yes, it is a CRM fixed-on-time(FOT) PFC Because it's a fixed charge-time and a constant slope transfer-time, the PWM modulation frequency MUST change because it has no other option. This ...
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2 votes
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How does this modulation cause sidebands?

A PFC in CRM mode uses a variable frequency, depending on the input voltage: check eq. (1) and (5) of your paper. When input voltage changes, duty cycle changes (eq. 1) and switching frequency depends ...
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PWM motor control - weird voltage ringing issue

It is worth considering the need for RC snubbers on your FETs (across the drain/source terminals). Does the ring frequency stay the same with the two motors? if so I would investigate snubbers. ...
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EMC pre-compliance test in the lab

Forget about the box. What you need is near field probes and a optionally log-periodic type antenna. You will always be able to tell if noise is from your EUT or from external just by switching your ...
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1 vote

Quartz Crystal with or without metal lid for EMI suppression?

Unless you're making a minimal cost high volume product, the difference in pricing between shielded and unshielded crystal resonators doesn't matter. Conservative design decisions should be made ...
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Trouble finding LDM for EMI filter

You're making it seem more complicated than it is. All two-port inductors are "differential mode" by definition. They can't be anything else: for common mode you need 4 ports at least. LDM ...
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CANBUS troubleshooting

I would suspect the motors before anything else. Most EMI from motors might be conducted noise, so you will likely be able to measure it with a scope. You need to narrow down the problem, is the noise ...
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ESD protection for ESP32 GPIOs

I would instead just use a TVS diode with a reverse standoff voltage of 3.3 volts. https://www.diodes.com/assets/Datasheets/DESD3V3E1BL.pdf
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