[john_jcb]

How does one tell if a walwart is regulated or unregulated?

I have a few laying around that I have no idea about. The two that I use for powering the TAH's I have are regulated, the only way I knew was to write the manufacturer and ask.

 

[guzzler]

you could use an O-scope to look at the output from the wall wart if you can. A wallwart with a really variable output is likely to be unregulated, a constant DC output will be regulated...

g

 

[KurtW]

A regulated walwart will give a nearly (depending on how good the regulation is) constant voltage regardless of the load current. You can measure the walwart with DC voltmeter when it is not powering anything, then again when it is powering something and see what the voltage difference is. A unregulated 12v 500mA walwart, for example, will probably put out around 16v unloaded so that it can meet the 12v spec with a 500mA load. If it was regulated, it would be close to 12 volts with or without a load.

Another factor in considering walwarts is filtering. A unfiltered walwart can put out quite a bit of noise when loaded.

Some wallwarts will indicate on the unit if they are either regulated or filtered, but many don't.