Wallwart AC and polarity

MIDIbox FM
1

Hi all,

I am following Duggle’s power supply, as seen here, using a 12 V AC powerpack / wallwart. The problem is that the wallwart was supplied with bare cables and no markings what could be ground, so I can’t work out what to connect to the ground of my breadboard of Duggle’s circuit!

I haven’t done any AC stuff before so bear with me here: with a DC PSU I would measure across + and - and look at the polarity shown on my multimeter. I have an AC setting on the multimeter and I have used this to measure across both outputs on the wallwart, but connected either way the multimeter shows no polarity. Any suggestions?

I presume it does matter which is negative and positive with such a wallwart?

Thanks in advance for any help

Dave mK

2

AC = ALTERNATING current, that means that it switches polarity at 50 (or 60)Hz (50 (or 60) times a second). So, there IS NO polarity, hence the cable isn’t marked :wink:

See: http://en.wikipedia.org/wiki/Alternating_current

3

I had a feeling that would be the case, just wanted to be sure before frying anything :slight_smile:

so I will connect up the cables this evening with a bit more confidence, thanks.

D