How Does a DC Power Supply Function and What Are Its Key Features?

[Jiggy-Ninja]

For most purposes, you do not need to use the Earth tie. I'm 1.5 years into my education and have not once had to hook anything to the Earth tie on the power supply, though some dorks at school still do it for some reason. vk6kro brought up a couple of specific situations that it might be helpful, but other than those you likely won't need to bother with it.

 

[PainterGuy]

For most purposes, you do not need to use the Earth tie. I'm 1.5 years into my education and have not once had to hook anything to the Earth tie on the power supply, though some dorks at school still do it for some reason. vk6kro brought up a couple of specific situations that it might be helpful, but other than those you likely won't need to bother with it.

Hello,

Some days ago I had the lead coming out of +ve terminal connected to the lead coming out from the ground which formed a junction. Then I attached the +ve terminal of the DMM to this junction, and the other terminal of the DMM to the -ve terminal of the power supply. The DMM gave me -ve readings.

And Jiggy-Ninja, the power supply has 2 prong plug .

Now I will try to ask what is puzzling me.

If I connect one lead to the ground terminal and the other one to -ve terminal, I will have 0V to -30V. Right? But what does this really mean? What is the direction of electrons? Before you answer this, I would request you to go through the rest of post.

I have always thought -ve terminal is simply taken as the ground because conventional current flows towards this terminal.

In 'actuality' electrons flows from -v terminal toward +ve terminal. I could get 0V to 30V when I have leads connected to +ve and -ve terminals. But I could also get the same range of voltage, 0V to 30V, when I have one lead connected to the +ve and the other one to the ground. Is then the ground also a '-ve' terminal because there should be something which is pumping electrons into +ve terminal?

And I was also able to set the current supply as constant current source following the instructions of Averagesupernova.

Many thanks for your help.

Cheers

 

[sophiecentaur]

Bringing electrons into this is a total red herring and doesn't help in any way. It's the equivalent of writing half of each post in French and half of it in English and expecting that it would help to make things clearer. We all agree (?) that electrons flow against the 'conventional current'. This will always be the case and I assume that you are not introducing it in a hope of showing some inconsistency(?). So please just talk in normal terms of V and I, resistance and PD etc..

There is not necessarily a reason for using the negative terminal as an Earth / Ground except that it is a very mild sort of 'convention'. The choice of ground connection is of no consequence to the internal workings of a circuit but it is relevant to how you connect between circuits. The 'negative earth' convention is usually adopted if you want to pass DC signals from one module to another if each module has a 'single sided' power supply. All voltages in a 'positive supply' circuit will be above ground and all voltages ing a 'negative supply' circuit will be below ground: not a convenient situation for connecting signals. For battery operated equipment, a single battery is usually the cheapest option and that dictates using a convention - if you want to pass DC signals in a straightforward way.

Hum and interference can be embarrassing without using some grounding system and often using an oscilloscope (and there is no option, using many other RF measuring devices) dictates using a grounded unbalanced signal connection. It is possible, on some 'scopes, to decouple the outer of a probe cable from ground but you can't rely on it being possible. None of this is magic- it's just pragmatic.

 

[vk6kro]

And Jiggy-Ninja, the power supply has 2 prong plug

In my country, this would mean that the case of the instrument was not grounded and that it wouldn't matter if you connected the outputs to the ground terminal or not.

Where are you?

 

[sophiecentaur]

And Jiggy-Ninja, the power supply has 2 prong plug

In my country, this would mean that the case of the instrument was not grounded and that it wouldn't matter if you connected the outputs to the ground terminal or not.

Where are you?

I am now confused. Are we supposed to be discussing a DC Power Supply problem or are we discussing the Mains Supply to a House?

 

[vk6kro]

This DC power supply apparently isn't grounded, so the silver terminal on the front panel has no connection to mains ground.

So, this thread which has gone on for 25 days and 35 posts has been a bit pointless.

 

[PainterGuy]

This DC power supply apparently isn't grounded, so the silver terminal on the front panel has no connection to mains ground.

So, this thread which has gone on for 25 days and 35 posts has been a bit pointless.

Hello everyone,

Yes, the power supply isn't grounded. I will post the readings tomorrow for confirmation.

I do not think this discussion was pointless. I learned many things from you and other people in this thread so it was very helpful for me and your effort was not wasted. Many thanks. Will post readings soon.

Cheers