Measuring voltage and current consumption

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1

Hello fellow engineers,
iam a rookie circuit designer and i have a big problem understanding current consumption and voltage in a circuit. In many articles i read that all components use the same voltage the source provides and that to measure current, you should add all the devices amp amounts. All good so far. The problem is my head cant make the connection between this information and the information we get from ohm's law and the schematics. According to ohms law you should add only the current from components that are connected in parallel since if they are connected in series they use the same current. Also if components are connected in parallel they have the same voltage but in series they have different voltages. Wouldn't that cause a malfunction?

2

sirick:
Hello fellow engineers,
iam a rookie circuit designer and i have a big problem understanding current consumption and voltage in a circuit. In many articles i read that all components use the same voltage the source provides and that to measure current, you should add all the devices amp amounts. All good so far. The problem is my head cant make the connection between this information and the information we get from ohm's law and the schematics. According to ohms law you should add only the current from components that are connected in parallel since if they are connected in series they use the same current. Also if components are connected in parallel they have the same voltage but in series they have different voltages. Wouldn't that cause a malfunction?

You have been reading crap, the internet is full of it. All of your statements about series and parallel circuits and Ohm's law is correct.

Paul

3

... except, perhaps, the part about causing a malfunction.

4

If you have several things powered in parallel from the same voltage source, you add the currents to get
the total consumption. There is no interaction between them as they see a fixed source voltage.

For instance several chips in a circuit may all be powered from 5V, so long as the supply can provide enough
total current all is well.

If you have things in series connected to a voltage source, they do interact, as the current is constrained
to be the same - for instance an LED and its current-limiting resistor interact to set the current dependent
on the voltage of the supply and the forward current curve of the LED.