so the by the "
ground" you mean the
wire that isnt hot?
Well, we don't really use the term "hot" to describe DC. "Hot" is used to describe a particular
conductor of an AC
circuit or the "true" of a
balanced signal. Your cable coming out of the brick there has two wires. One corresponds to the big "plus" symbol on the brick, the other to the big "minus" symbol. The "plus"
wire is positive with respect to the "minus"
wire; the "minus"
wire is negative with respect to the "plus"
wire.
For a positive
power supply
circuit, we take the "minus"
wire as common (this is also a "negative
ground" arrangement like your car), "common" being the signal that measurements are referenced against. We also
call this "
ground", though "
ground" can mean a bazillion different things.
The
wire that's positive with respect to
ground is usually given a label like "+30" or, in the case of a single-voltage
power supply, simply "
power" or "dc".
To find which
wire is which, first make sure you have a DC voltmeter, then chop off the end of the DC cable. Separate the conductors of the cable a ways and strip them.
Plug in the
power supply. Put the red probe on one
wire and the black probe on the other. Look at the
meter. If the reading has a leading minus sign, then the
wire your red probe is touching should be used as
ground. If the reading does not have a leading minus sign (that is, no sign or a plus sign), then the
wire your black probe is touching should be used as
ground.
and where can i find the
resistor/
terminator.
Radio Shack will have something close enough, though they'll overcharge you.
But based on your electronics knowledge, I'd really caution you to simply buy a proper CC
power supply.
Power supply circuits are simple, but it takes more knowledge and experience than you've got, no offense. "Which
wire is which?" and "What's
ground?" are huge red flags that you shouldn't be poking around inside PS circuits.