My 12V adapters label is wrong?

Thread Starter

Bod

Joined Sep 18, 2016
256
So I Have a 12V DC supply, it came from a set of speakers. It is clearly labelled
INPUT: 230V ~ 50Hz
OUTPUT: 12V DC - 500ma 6VA
Simple? Not quite. When it is measured with a multimeter it is giving a reading of 16V Dc. Does that mean the label is wrong, or the circuitry is faulty?
P.S That is the only adapter I can use for a set of light strips. Also say if you need any pictures of it.

EDIT
The adapter does work on the light strips without blowing them, it was a question out of curiosity more than anything else.

Thanks.
 
Last edited:

LesJones

Joined Jan 8, 2017
2,533
It is probably a unregulatede power supply so it will give a higher voltage with no load on it. Load it with a 24 ohm resistor and measure the output voltage at the rated current of 500 mA.

Les.
 

R!f@@

Joined Apr 2, 2009
9,682
Not all all.
You are measuring the unloaded voltage
At 500mA loading voltage will drop to ~12VDC

This is normal in unregulated PSU's.
 

Thread Starter

Bod

Joined Sep 18, 2016
256
It is probably a unregulatede power supply so it will give a higher voltage with no load on it. Load it with a 24 ohm resistor and measure the output voltage at the rated current of 500 mA.

Les.
Thanks! Thats the answer, it's definitely not a regulated supply.
Well that was really simple.
PS. I'm being a pack of resistors because I'm low in them, so I don't (at the moment) have a 24ohm resistor.
 

dl324

Joined Mar 30, 2015
10,072
I don't (at the moment) have a 24ohm resistor
At 12V, that resistor would be dissipating 6W. Most of us wouldn't have one on hand.

For load testing, I prefer to use an LM317 with a few values of power resistor. I can adjust the voltage to get the current draw I want without needing a bunch of power resistors values.
 
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