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14 votes

Why does power supply have a negative rail if can only output positive voltage?

The power supply itself has two output terminals, labelled \$\boldsymbol{+}\$ and \$\boldsymbol{-}\$, and produces up to 60 V between them. Remember that voltage is defined only as a difference ...
Hearth's user avatar
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8 votes

Why does power supply have a negative rail if can only output positive voltage?

If the output can't be negative,... Whether a voltage is positive or negative depends on how it is measured. The negative (black) terminal is the reference against which the positive (red) terminal ...
RussellH's user avatar
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6 votes
Accepted

PCB layout for crystal of MSP430FR6047

I imported the PCB files into KiCad and as expected, the PCB editor shows it as a solid copper plane. In the schematics a net tie is used, so the different ground planes are really connected even if ...
Justme's user avatar
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5 votes

PCB layout for crystal of MSP430FR6047

They are "net ties" which are used to tie together different parts of the same electrical net in a way that controls how current flows. It is a way of capturing design intent so it does not ...
Spehro Pefhany's user avatar
2 votes

Can differential probes be used with floating oscilloscopes, such as handheld/tablet scopes?

First, If your using a floating scope, the standard single-ended probes are already going to act as differential probes - your ground is already floating so you gain no advantage using an active ...
MOSFET's user avatar
  • 4,707
2 votes

Can differential probes be used with floating oscilloscopes, such as handheld/tablet scopes?

If something were to arc over inside their product the 10MΩ could become something much lower and the scope could be energized at high voltage. Maybe they have protection that shunts higher voltages ...
Spehro Pefhany's user avatar
2 votes

Can differential probes be used with floating oscilloscopes, such as handheld/tablet scopes?

It needs USB-C for power. If you need to use it floating then the power supply must have suitable isolation as well as the scope.
Kevin White's user avatar
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2 votes

Why does power supply have a negative rail if can only output positive voltage?

The green socket is in fact chassis earth and connects to the protective earth (PE) that comes into the power supply from the wall socket. That green socket is usually galvanically isolated from the ...
Andy aka's user avatar
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2 votes

Dedicated ground vs power cord ground?

That ground terminal on a power supply or function generator or other piece of equipment is typically intended to give you a way to connect other things to mains ground, not as a way to ground the ...
Hearth's user avatar
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1 vote

Can differential probes be used with floating oscilloscopes, such as handheld/tablet scopes?

Using a grounded 'scope controls the common mode voltage of the differential probe. The other answers have coverered the safety aspects of having the 'scope and the device under test at different, ...
Neil_UK's user avatar
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1 vote

My isolation transformer has its protective earth connected to the output neutral. How should I rewire it for my home lab for "DUT probing"?

An isolation transformer makes things both safer and more dangerous: If you touch one of the output wires, no current will flow through you and to Earth, so you won't get zapped. However, because no ...
bobflux's user avatar
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1 vote

My isolation transformer has its protective earth connected to the output neutral. How should I rewire it for my home lab for "DUT probing"?

Your device has an isolation transformer in it, but the device itself isn't called an isolation transformer. Mostly because it doesn't isolate. The device with your description is a "line ...
Justme's user avatar
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1 vote

Why does power supply have a negative rail if can only output positive voltage?

You may not want to tie your negative terminal to chassis ground when there is the possibility of picking up white noise off that ground. Floating the circuit and tying it to a different ground is ...
Fred Sopron's user avatar
1 vote

Problem: Transient Voltages in Grounding Circuit Cause comms loss

A ~10kV spark discharge is a pretty intense level. When from an ESD generator, it's, well, that's ESD, at about the highest level normally seen (8kV contact / 15kV air discharge). You don't mention ...
Tim Williams's user avatar
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1 vote
Accepted

Grounding Lug Straight To Chassis

You can use lugs for a chassis connection. What you show is about the same as a mechanical lug, the only difference is one is a crimp on connector and one is a screw/crimp which is less reliable in my ...
Voltage Spike's user avatar
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