is there a circuit i can do to test the maximum output current of device?
The answer to this depends on the circuit behind the power source.
If the power source is current limited, you can use an ammeter and a variable load. Connect both in series to the power source. Increase the load until the current is limited by the power source.
If the power source is not current limited but fused (which is in a way a kind of current limiting, though destructive), you can use the same method, but instead of limited current watch for the current shortly before the fuse acts. Replace teh burnt fuse afterwards.
If the power source is not obviously current limited, better look for technical data (manual, type label etc.) that gives you the max. current. Operating such a power source above the rated current can easily destroy it. Or it may trigger a fuse in an unexpected location, e.g. in your main distribution panel.
does the output current determine by the drained device or the output source value?
The current on the power source's type label, manual or similar is the max. current that power source is capable of delivering without failing (at least in theory, may not be the whole truth for some cheap knockoffs).
It is not the current actually delivered to the load or drawn by the load. The typical power source is a voltage source, which means the output voltage is fairly fixed under normal load. The current drawn by the load is then determined by
I = V/R
where
I = current
V = voltage
R = load resistance or the equivalent thereof for complex loads
Valid for e.g. batteries, wall warts, mains outlets and the like. These are called voltage sources.
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Don't get distressed by the following rant of mine:
To add to the confusion there are also current sources which are theoretically able to deliver a constant current and instead vary the voltage depending on the load acc. to V = I × R. An example for this kind of source is a
current transformer used to measure high currents by transforming them to small, manageable currents.
Other examples are electronic current sources which use electronic components to create a constant current from a voltage source.
However, "normal" power sources are
not current sources but voltage sources as described above.