The 220 volt AC to 9 V DC adapter outputs 12 volts without load - is this normal?

Question

Electronics

The usual adapter, for powering any devices (Panasonic), on the case there is a plate input 220V AC, output 9V DC. Measured without load - the output is a little more than 12V DC. I was going to use it to power an arduino, but a question arose about the output voltage of this adapter. Maybe it will have 9v under load? I’ll try to connect and measure something, but it’s still unclear why the output without load is not 9v, but more.

Answer 1

You can pick up a resistor in parallel so that the voltage stabilizes at 9 volts

Answer 2

It can have 9 volts under load, but it's better to take a normal adapter. In any case, when measuring voltage through the Arduino ADC from a low-quality unit, there may be interference and this will affect the results. It is not known how high-quality voltage such a unit produces, most likely - poor quality.

Answer 3

Yes, without load, transformer power supplies can produce more voltage. If your device consumes much less than the one for which the power supply is intended, the voltage will remain 12.
It is likely that the arduino will work fine at 12v. Search for information on this topic

Answer 4

The Mega 2560 works great on 12V. Yes, and this is within the operating parameters that are declared by the manufacturer. In any case, when replacing the power supply, watch for a short time that there is no heating on the voltage converter. Just for insurance.