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MisterBill2
- Joined Jan 23, 2018
- 27,639
The wall wart supplies are in three major kinds, and a fourth minor kind. The big heavy ones use a mains frequency iron core transformer to step the voltage down to some lower voltage, and then there are rectifiers to convert it to DC, and a small amount of ripple filtering. That variety is often OK quality, but the 12 volt 2 amp max supply is not regulated and so the no load voltage will be higher, 15 or more volts. But at a 2 amp load it will be close to 12 volts.
There are also a very few regulated transformer supply wall warts, Their no load voltage is quite close to the labeled value.
Most common now are the electronic switch-mode supplies, most of them are fairly well regulated. They are smaller and much lighter and they may fail completely if overloaded excessively. But never use one of them without measuring the output voltage before connecting the item to be powered. They might have a failed regulator and put out a much higher voltage than the label claims.
The final kind is just a transformer, and the output is AC They can really damage a piece of equipment that needs a lower DC voltage,
There are also a very few regulated transformer supply wall warts, Their no load voltage is quite close to the labeled value.
Most common now are the electronic switch-mode supplies, most of them are fairly well regulated. They are smaller and much lighter and they may fail completely if overloaded excessively. But never use one of them without measuring the output voltage before connecting the item to be powered. They might have a failed regulator and put out a much higher voltage than the label claims.
The final kind is just a transformer, and the output is AC They can really damage a piece of equipment that needs a lower DC voltage,
