AS I came from a country where we use the french system in defining the voltage current arrows in electronic circuit, I am confused about the German/Austrian system where I see the voltage arrow is directed from positive to negative and this makes me confused when it comes to analyse complex circuit especially with diodes and mosfet. any clarification is more than welcome enter image description here

here one of the circuit if I use the German Terminology enter image description here

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    Can you add pictures of examples? Everyone uses the same polarity symbols and + is always a higher potential than -. – Transistor Nov 17 at 17:18
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    That is very strange. The capacitors are polarised so + is the top. Vin should be pointing up as should Vout. VL could be as shown at the instant the switch is opened. It looks like a boosting power supply. – Transistor Nov 17 at 17:27
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    Can you add some more context? What book does this come from and what text is around it? – Transistor Nov 17 at 17:32
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    The tip of the voltage arrow is in the direction of the Electric field from plus to minus. The arrowhead on the "negative" side. – G36 Nov 17 at 17:33
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    German nomenclature uses U instead of V for voltage identifiers to avoid confusion with the unit symbol V. Also, the symbols for voltage sources and current sources are different, maybe it's that? For a source, current and voltage arrows have the opposite direction, so P=U*I is "negative". That means power is flowing out of a generator if U and I are positive. – Janka Nov 17 at 17:36
up vote 2 down vote accepted

I think you stumbled over a convention called Verbraucherzählpfeilsystem. It's pretty common in German EE conventions.

All items are treated as loads, regardless if they are loads (Verbraucher) or generators.

schematic

simulate this circuit – Schematic created using CircuitLab

This idea is you don't have to put the arrows on the schematic. You simply write Verbraucherzählpfeilsystem somewhere prominent, then write

$$I_g = -100A$$ $$I_l = 100A$$ $$U_g = U_l = 100V$$

and everyone agrees \$I_g\$ and \$U_g\$ belong to a generator, because \$I_g\cdot U_g\$ is negative.

You could also write Generatorzählpfeilsystem somewhere and use the exactly opposite definition. But that's not so common in German EE.


Also note German convention is using U instead of V for voltage identifiers to avoid confusion with the V unit symbol.

  • Yes, exactly but how can you figure out where the current is flowing when it comes for example a circuit with diodes and transistor as I edited it on the post. – Yaakov Nov 17 at 18:03
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    Diodes and transistors are loads. Assume the current direction as positive in which the element is meant to conduct to fulfill its role in the circuit. – Janka Nov 17 at 18:13

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