AC/DC Adapter

[Thomas]

I Have an AC/DC Adapter that has a variable voltage settings. I
figured i could use that to power my bread board. So i cut the
connector and and stripped the wires. I found somethign i wasn't
expecting to find.

There is 2 cables, 1 with a white plastic covering and the other is
exposed copper (i think) wire.

I am kind of lost now, can anyone please provide some directtion.
Thanks.

 

[CFoley1064]

Subject: AC/DC Adapter
From: tomtiv@rogers.com (Thomas)
Date: 8/12/2004 10:17 AM Central Daylight Time
Message-id: <14b25ac0.0408120717.30110a1e@posting.google.com

I Have an AC/DC Adapter that has a variable voltage settings. I
figured i could use that to power my bread board. So i cut the
connector and and stripped the wires. I found somethign i wasn't
expecting to find.

There is 2 cables, 1 with a white plastic covering and the other is
exposed copper (i think) wire.

I am kind of lost now, can anyone please provide some directtion.
Thanks.

Hi, Thomas. At your apparent level of experise, it might be a better idea just
to junk the wall wart and start over. In order to learn something about
electronics, you have to start somewhere, and good working basic equipment is
part of that.

A variable voltage wall wart isn't really a good idea for a newbie to power
breadboards and such because:

* It isn't current limited. If you short it out or place an excessive load on
it, you might burn up the wall wart. You could put a fuse on the output, but
that might get a little expensive for a newbie.

* It has an unregulated output voltage. That means the voltage will change
depending on the load you apply, with greater 120 Hz/100 Hz ripple for greater
loads. For instance, a 12VDC 300mA wall wart will show 15VDC or so with no
load, and 11.5 or 12.0VDC or so with 300mA load. At full load, you've actually
got several volts peak-to-peak of ripple.

If you want to have something you can use for basic breadboarding, you might
want to look at a hobbyist kit which will give you a regulated, current-limited
DC supply (Look for one based on the LM723 IC). Either that, or get an
electronic power supply surplus or on ebay.

Good luck
Chris