The power supply case is permanently grounded through the power cord for safety.
The internal circuitry can be floating unconnected to the case. The output terminals
have to be insulated from the case, though there is usually also a true ground terminal
that is only connected to the case.
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Yes sorry, what I should have written was that the PSU is safe due to it be grounded but on the secondary site of the transformer, do I think / ask you if it is not better to avoiding to ground any of the leads? 🙂
An electronic circuit does not need a true "ground" connection to work, but often there is one for safety.
For example, a flashlight has no ground connection. Neither do most battery operated devices,
like a radio. Under 50V is considered safe enough for no grounding, but higher voltages would usually
require that the circuit be connected to ground in some way, or specially insulated.
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I know that we are only talking about 10V here, but what if, lets say it was a +-50V unit?
Yes and direct to the main earth?
I do really thank you for using so much time on my small project, it do mean a lot for me!!
Yes, normally through the power cord safety ground wire (green in the USA). Be careful now.
Thank you, but as long we are talking about 10V, do I not feel the urge to protect myself against secondary site🙂
Unless it reduces noise?
Generally, it's wise to avoid touching any part of a powered electronic circuit with your hands,
and only use insulated probes. Just a good habit for safety. There's no problem with, for example,
a child's electronic hobby kit that runs on a few volts of batteries, though.
Noise is a whole different subject.
Yes that sounds logical... noise , about that, if I try to power a chip, lets say a op-amp do electrical noise get worse, better or no change, by earthing secondary side? I have heard some say all three things, but that was just as a postulate, without any short explanation🙂
Noise is a large topic, with many books on the subject. Your "ground" could even be noisy.
Some circuits (balanced) are designed to cancel out noise that is picked up. Here is an intro.
Reducing Signal Noise in Practice | Precision Digital
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LOL okay, so what I am asking is about the same if I asked you: "and how do i build a spaceship around the psu?" 🙂
I have choosen standard diodes to rectify the AC, but it looks like I'll lose a lot of voltage 3.2V, I know that I can use difference diodes or even op-amps, and that's fine on my low power project, but what about something insane like 100V 25A, just to take some numbers.
My reason for asking is that I do like to know more about "what if" heat, power and where safety is kicking in.
The 50V point is where things get serious. Usually for design you work backwards from the desired output,
so the transformer voltage/current is chosen last. A simple supply is not real efficient, power is lost in the regulator,
diodes, and transformer. Over design costs money, though. Many current power supplies use switching,
which reduces wasted power with more complex circuits.
Okay so I have to go the other way, from out to in and not as now.
smps is an whole other beast, isn't it? I understand that smps do deliver less clean power and should be something you do not start building as a noob?
SMPS can be very good if carefully designed. You have to be able to design a linear supply
before you can deal with SMPS design, which is much more complex.
I think I can design a fundamental psu and the formulas, I can not design an Adoino controlled psu yet, but am trying to climb the latter🙂
Do I understand you correctly in that a well build smps can be as good as a linear power supply, that you can not measure any difference on the power out?
It's been done, by HP etc. as well as hobby. Arduino controlled lab variable power suply
Yes, even linear regulators have noise. It's all a matter of design and cost.
Yes that's perhaps why Agilent takes a lot money for there psu's🙂
But with a scope and lots of time, and reading, it should be possible to build a 10mV ripple, minimal noise unit?
Fantastic, something to look forward to, do you know any place that are good for a noob to start on learning? 🙂