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WS2813 LED data permanently latching on power-on

Start by reading the manual of your MCU. If your GPIOs during power-on are high-z, I would attach a pullup to /OE (pin 19) of the 74HCT245. You have to cut the existing trace to GNDA of course. Then ...
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Crystal Radio Troubleshooting

Your first radio had a loop antenna which responds to the magnetic field component of the incoming AM broadcasts .The second version with the wire antenna will also respond to electric field .It so ...
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1 vote

Is 'grounding by chassis' achieved by the screws?

Screws and standoffs can be used as conductors either for connecting a pcba to the chassis or other elements. For example capacitors and more bulky semiconductor devices might use screws to make ...
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Crystal Radio Troubleshooting

You need to connect a resistor across the crystal earpiece. You may also try this double-tuned circuit. It may be redrawn this way to show how the coil is wound. The antenna circuit is series-tuned ...
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3 votes

In a DC power-supply design, is it safe to connect the GND of the secondary side of the transformer to the AC input part?

The mains transformer input MUST NOT be connected to GNDA. The mains transformer current should circulate between live and neutral. The mains side safety ground is just that, for safety. It should not ...
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1 vote

In a DC power-supply design, is it safe to connect the GND of the secondary side of the transformer to the AC input part?

Assuming "GNDA" symbol on the left of the transformer means mains neutral is connected to the circuit ground "GNDA"... If the purpose of the circuit is to measure mains voltage, ...
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In a DC power-supply design, is it safe to connect the GND of the secondary side of the transformer to the AC input part?

I’m not sure why your colleague is using ground as a return for AC. If this is from the AC mains then it should certainly return via a neutral conductor - this will eventually be earthed somewhere, ...
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ESD damage without earth ground

Turn it around: How does a totally floating human damage an earthed circuit by ESD event, if there is still no ground path? Would a totally floating (and similarly charged) circuit be damaged by touch ...
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1 vote

ESD damage without earth ground

The entire device can be approximated as an equipotential surface, like a metal sphere. Say, you stand on an insulating surface, and charge yourself from a VanDeGraaf generator to a MV or a few, then ...
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2 votes

Two separate PCBs and common ground for UART communication

A direct connection between two GNDs with jumper leads is enough.
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3 votes

Two separate PCBs and common ground for UART communication

If that is using standard UARTs, you absolutely need the ground as reference for the Tx and RX. Where you see on two connections, then the two ends must have a common ground that is not shown there. ...
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