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I found a power supply in my workshop that is marked as 12v@2A it is the typical Chinese power supply to drive leds so it is supposed to be Current Source, but I'm not sure at all, so I would like to know if there is any simple test I can do on the power supply unit to determine if it is a constant current source or a voltage source.

Side view Connector view Thanks in advanced.

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    \$\begingroup\$ With the "12V 2A" sticker it's most certainly not a constant current source, but a constant voltage source that can deliver up to 2A. \$\endgroup\$
    – Marcus Müller
    Jun 7, 2016 at 9:03
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    \$\begingroup\$ I think the Vo ADJ might be a clue \$\endgroup\$
    – JIm Dearden
    Jun 7, 2016 at 9:03
  • \$\begingroup\$ Also, you know what "constant current" means, right? \$\endgroup\$
    – Marcus Müller
    Jun 7, 2016 at 9:03
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    \$\begingroup\$ No test needed, there are V- and V+ outputs, there's a Vo adjust trimmer. DC output says: 12 V, 2A. If it was a current source type LED driver it would not state 12 V as the output voltage but a certain range like 10 - 15 V. So it's a 12 V Constant Voltage supply \$\endgroup\$
    – Bimpelrekkie
    Jun 7, 2016 at 9:04
  • \$\begingroup\$ It means that no matter what load you attach, the current will be constant. So attach two different loads, and observer current. \$\endgroup\$
    – Marcus Müller
    Jun 7, 2016 at 9:04

2 Answers 2

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It appears to be a fixed voltage power supply. 12Volts at up to 2A. It has a potentiometer marked "Vo Adjust" which would be "output voltage adjust" which would be a useful thing on a constant voltage supply

It does not appear to be a constant current supply. A constant current supply would have a voltage range rating (say, for example, 5V-20V) and a current rating. This has a single voltage rating (12V) and a single current rating which is typical for fixed voltage supplies.

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How to diferentiate current source and voltage source

The answer is very simple

1-voltage source enter image description here

Ideal voltage source have a small internal resistance i.e. The voltage does not change when the load change It gives a constant voltage no matter what is the load

2-current source Physically does not existed But in theory current source provides a constant current, as long as the load connected to the source terminals has sufficiently low impedance

An ideal current source has an infinite output impedance in parallel with the source. A real-world current source has a very high, but finite output impedance

For more information see the link below

https://en.wikipedia.org/wiki/Voltage_source

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