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whats the difference between 1 terminal power and 2 terminal power in falstad?

dragon

Oct 31, 2022
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So, in falstad you get 2 terminal power, but u also get 1 terminal power, which is the positive without the negative and vice versa.

Whats the difference?
 

dragon

Oct 31, 2022
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Yes but how do you use it - whats the difference of use, its obviously a different kettle of fish.
 

Harald Kapp

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its obviously a different kettle of fish.
Not really.

Obviously the 1 terminal power supply implicitly assumes that the other end (not shown 2nd terminal) is tied to GND (0 V).
Every power supply needs two terminals. Sometimes, as is the case here, one terminal, the reference potential, is not shown to simplify the schematic.

See this example:
1679419716524.png

versus this example (voltage source also set to 5 V):
1679419902947.png
 

dragon

Oct 31, 2022
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Thanks for the help.

It doesn't need a ground to operate, you can send it to a negative 5 as well if you want.

How do you actually implement it in a real circuit? Doesn't a positive always come with a negative?
 

Bluejets

Oct 5, 2014
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It doesn't need a ground to operate
In the real world where most of us reside, a circuit requires at a minimum, 2 conductors to complete.
In nearly all instances, one is tied to the chassis.
 

Harald Kapp

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It doesn't need a ground to operate, you can send it to a negative 5 as well if you want.
No, it does require ground.
Ground is the reference potential (0V) for the simulator. Even if you don't see it in the schematic. That's because voltages alöways, always, always are between two points. A single point can't have a voltage.
In any real circuit (which you never bothered to build and show us) you will have voltage sources with two terminals. Always.
 

dragon

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So you showed me two ways to do it, there is one as a circuit, and other way which is just a line that ends at ground.

The one as a circuit, seems to have no current going to the ground there, it looks like a dead wire.
 

Harald Kapp

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The one as a circuit, seems to have no current going to the ground there, it looks like a dead wire.
Right. For current to "flow" it requires a closed loop. There is no loop from the lower right connection point (post #5, second picture) to gnd.

In Falstad you can draw the circuit like this, too:
1679463652948.png
Falstad obviously inserts an implicit gnd (or 0 V reference point) to do the math for the simulation. Other simulators like SPICE require an explicit definition of the ground potential.
 

dragon

Oct 31, 2022
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Ok got it, thanks for the help.

So with the +5v and the ground, how do you implement that in a real life circuit?
 

dragon

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you cant just conduct to a chassis of a machine with half a battery on it???
 

Harald Kapp

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Why half a battery? Where's the other half? #10 shows a complete battery.
 

dragon

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I mean in #5, with the +5 volts and ground, is that setupable in real life??
you cant have +5 volts without -5 volts!
 

Harald Kapp

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you cant have +5 volts without -5 volts!
Yes we can. +5 V is the positive pole, 0V (ground) is the opposite pole.
is that setupable in real life??
Of course it is. Read what I wrote:
Ground is the reference potential (0V) for the simulator. Even if you don't see it in the schematic.
Ground is only not shown in the simulator's schematic, it is implicitly assumed to be present. In real life you need to make a physical connection as shown in post #10.
 

dragon

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I still dont understand. :(

Can you please demonstrate me an example of using +5v and ground in real life?? I'm totally confused about it.
 

Bluejets

Oct 5, 2014
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I still dont understand. :(

Can you please demonstrate me an example of using +5v and ground in real life?? I'm totally confused about it.
I think it's time you gave some serious thought to taking up fishing or playing bowls as you just seem completely unable to grasp even the simplist basics.
 

Martaine2005

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+5V and -5V will have a Peak to peak of 10V.
+5V and 0V will give you 5V.
The GND symbol (use your imagination) is the GND or Negative connection to the battery or power supply. It keeps the schematic tidy. It’s an invisible connection!. BUT (use your imagination) IS connected.

Martin
 

dragon

Oct 31, 2022
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I think there is a trick to this tho, its definitely different to 2 terminal power, it seems to behave in a different fashion.
 
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