Why is it necessary to unite the land?

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Lopus2020-01-28 21:52:06

Arduino

Lopus, 2020-01-28 21:52:06

I often notice that they write about the need to combine the earth for an electrical circuit.
For example arduino and some consumer. Why and why not make them different?

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4 answer(s)

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Vladimir Kuts, 2020-01-28
@fox_12

On the fingers:
On the "ground" of the arduino there can be a potential of 0 V, and on the "ground" of the consumer - 200 volts relative to the "ground" of the arduino. Therefore, instead of the expected 5 volts, 205 volts can fly from the consumer to the arduino with all the ensuing consequences and colorful special effects.
To prevent this from happening - the ground potentials of the arduino and the consumer are equalized by connecting them together.

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lonelymyp, 2020-01-29
@lonelymyp

Because only Tesla could transmit electricity through one wire, but he died.
Therefore, everyone except Tesla has to use the second wire, which is precisely the role of the united "earth".

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VT100, 2020-01-28
@VT100

It is better, of course, to give an example of misunderstanding. And the question is too general. For example:

Because the circuit of any signal must be closed. So it is easier to drive electrons along it - the efficiency is higher (and there is no need to engage in spiritualism).
One wire is a signal from the arduino to the consumer. The second is the common potential from which the signal level is measured.

And these are not different interpretations, but different points of view on the same hardware.
Different "earths" are made if it is necessary to provide galvanic isolation of one circuit from another. For example, a cardiograph.

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evgeniy_lm, 2020-01-28
@evgeniy_lm

I often notice that they write about the need to combine the earth for an electrical circuit.

Voltage is a potential difference. Those. in two voltage sources, we must have a common potential relative to which the voltage is measured.

why can't it be different?

Not only is it possible and even necessary, but it is difficult and expensive, in electronics it is called "galvanic isolation
" transistor) high voltage did not get to the output of the MK. To do this, a current-limiting resistance is placed in the base circuit.
If the load is powered by an alternating voltage of 220V, then without galvanic isolation, no way.