Covering a couple of points still...
OK, after more research I'm finally getting my head wrapped around this a little and I see that I am going to have to go with a switching/switch-mode power supply for higher Amps.
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Not necessarily. You can if you want to.
I still would like to buy the parts myself and build one on my own to teach myself a lesson (and to get over my fear of AC power), but I have no idea how I would get a specific current from a DIY switch-mode power supply. I understand how to convert from AC to DC, but how would I get say 6 Amps out of the power supply? Is there a good resource on switch-mode power supply building that can be used, or do you use a data sheet, or are there some kind of standard calculations to get to 6 Amps, 8 Amps, or whatever is needed?
I hope there is not a misunderstanding here? A normal PSU that we are talking here produces a constant voltage. The magnitude of the output current however is determined by the load you connect to the PSU, according to Ohm's law. So the only calculations you do are to make sure the PSU is _capable_ of providing the required current. You don't "push" the current into the load. Earlier you stated that your motor will draw 300 mA when idling and 5 A when stalled. That is a typical example. The motor draws the current instead of the PSU pushing it.
As to why the variation in this case - it is simple:
1: A (DC) motor is a generator as well. Turn the shaft and you can measure a voltage from the motor terminals. When the motor is turned at the nominal speed, it will in principle produce the nominal voltage. If you now connect said nominal voltage to the motor terminals, _no_ current will flow because there is no voltage difference.
2: Clamp down the motor shaft to prevent it from turning. This means the motor can generate no voltage because the shaft cannot turn. Now feed the nominal voltage to the terminals. As there is no voltage present (it is called back EMF by the way) the only thing limiting the current now is the resistance of the motor armature winding. That is usually quite low so a considerably larger current will flow. In this case 5 amps from which we can immediately calculate the armature winding resistance Ra = 12V/5A = 2.4 ohms. A typical figure for a small DC motor.
What happens when your motor is idling and you introduce a load? The motor speed changes in accordance to the formula
U = v/Kv * RaIa, where
U = motor terminal voltage
v = motor speed (typically in units rpm)
Kv = motor velocity constant (typically in units rpm/V)
Ra = motor armature resistance
Ia = motor armature current
The equation has 2 terms reflecting cases 1 and 2 above. Firstly the term v/Kv describes the generation of back EMF as a result of the motor rotation. An ideal motor idling will draw no current because the back EMF exactly matches the terminal voltage due to this term. In practice when the motor is loaded it slows down and the back EMF no longer matches the terminal voltage exactly. Enter the second term RaIa. Now the armature current increases thus producing more torque to match the load but also to induce a voltage loss due to ohmic resistance in the armature circuit. The sum of these two term always exactly matches the supplied terminal voltage.
So in the end your power supply must be able to provide the Ia in the equation above, in the case when v = 0 i.e. the motor is standing still. This is the 5 amp stall current. It is the maximum the motor will draw in any situation unless you change the supply voltage.
Mouser has AC/DC Switching Converters under their Power Management IC's section, but the highest supply current I could find was 3 A, so how do you get to 6 Amps?
Also, switching power supplies like the Mean Well products that are just a semi open enclosure with screw terminals, are those the same thing as regular switching power supplies, just minus the full enclosure and plug? I guess you would just mount the female receptor to your projects enclosure and wire it to the screw terminals?
Thanks for the help.
You can use a Mean Well PSU, no problem. Only it is unnecessarily sophisticated for this kind of use but if you don't mind then no problem.
What you should not do is don't attempt to build a mains powered switchmode PSU yourself. It is not something you start with, it is something you graduate into. There are numerous safety aspects involved, not to mention EMI issues and definitely a lot of non-elementary circuit design and layout experience required.