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Is a non-isolated (shared ground) topology like this is problematic for this use case? Should I use an isolated topology instead (flyback with transformer?) Not necessarily, but any EMI that induces currents into the OV line or -48V line will make the DC to DC converter in remote equipment box susceptible to the EMI. The other problem from the looks of the ...


3

If it's automotive, consider EMI for your solution as you likely need it qualified. You have to prevent a large loop between battery positive, display PCB, LDO, sensor PCB, sensor, chassis, back to battery negative. This happens if you cut the chassis bond of the display board, although it will solve the ground loop. The large loop will remain and cause a ...


3

The minimum gain to start oscillation of a Wien Bridge Oscillator is three. So, if your circuit negative feedback resistors are in the ratio 2:1 then theoretically this is sufficient to start an oscillation. However, it may take a year to build-up and, with slight losses (op-amps are not actually ideal) or tolerance issues on the two feedback resistors, then ...


2

That circuit has several big design faults. D2 short-circuits E3 to ground. A high current will flow which may destroy the battery, D2 or both. Both ends of D3 are connected to ground. It will never light. E1 is backwards. When S4 is closed it will short-circuit E1 to ground. A very high current will flow but there will be no voltage available to power ...


2

What you have is a power supply with floating output. Since the output is floating, it is basically not referenced to anything in DC voltage terms - not even the mains earth - but there is stray capacitance of the switch mode transformer so for high frequencies there is an AC impedance between mains side and isolated side. Even if mains neutral is connected ...


1

How come the (AC) voltage between earth and GND is a means to qualify the galvanic isolation of a phone charger? Shouldn't it be between GND and neutral? The earth is not connected in the circuit. On the mains side, neutral and earth will be connected at some point (and maybe several points). So measuring between power supply GND and earth is much the same ...


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If one of the inverter's output legs can't be grounded, I suggest getting an isolation transformer and run the inverter through that. Then, tie one of the transformer output legs to neutral, and also bond it to ground at your distribution panel where your breakers reside.


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You need to get the display PCB and sensor PCB grounded at a single point, and that can only be at the sensor itself. So disconnect battery ground from the display PCB (LDO etc.), feed it through a separate wire to the sensor PCB, and 'ground' it as close as possible to the sensor. Then run that ground back to the display PCB through the existing ground wire ...


1

However the LED sometimes randomly flickers at a very low brightness in the dark even if it has no contacts to any conductive objects. Your eyes are very sensitive to low light, and LEDs can work on very little current. Simplest solution is to wire a resistor across the LED strip which shunts away any small currents that might be induced in the wiring. A 1 ...


1

the earth (which we can approximate as an infinitely large conductor with an infinitely large capacitance). Capacitance is a relationship between two different volumes of space (generally conductive volumes). It does not make sense to speak of the capacitance of a single (conductive) volume of space, such as the earth. That is the primary error you are ...


1

The Earth's huge capacitance means that it can exchange a lot of charge without changing potential. Your circuit, however, has a comparatively tiny capacitance. If some charge is added or taken, it changes potential a lot (compared to the change in the potential of the Earth). So it is not the Earth changing its potential to meet the circuit, it is the ...


1

The voltage you're seeing is leakage past the isolation transformer and the EMI-suppressing Y cap in the supply. It's not harmful for a compliant supply, but the leakage can disturb some circuits due to AC coupling to the environment. Go ahead and ground your stuff. This will shunt the the leakage and kill the AC voltage you're measuring. Related: About ...


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