Building a Super Simple 12V 30A Power Supply

Hello, I am the Summoner of Robots and joining me today is a DC power supply, a DC motor speed controller, and a voltage gauge. I’m going to build the cheapest linear variable power supply. So, these are both rated to 30 amps at 12 volts which is a bit of… overkill, but it’ll be nice to know that I’m not going to fry anything unless I try some really stupid stuff, which I hopefully won’t be doing. So, line voltage goes into these terminals over here and then 12 volts comes out from these ones and then that’s going to go into this DC motor controller and come out as a variable voltage based on where this knob is, and I’m going to use this voltage gauge to see what that voltage is at a given time.

01:16 - and this is a little stand, that I glued together out of some pieces of scrap wood, to put the voltage gauge in. So I just pop it in there, looks pretty nice. I think it’s gonna go on top of the motor controller because then I’ll be able to just plug it in to the outputs that I need so that’ll be pretty convenient. I think right now I’m gonna paint this. okay well it’s several hours later cuz I kinda forgot I was doing this for a bit but this is nice and green now so now I think I want to take this and glue it onto the top of this motor controller so that will require warming up the hot glue gun, and I think I’ll start on the wiring while I’m doing that. where’s the hot glue gun? I’ll go get the hot glue gun.

03:37 - This behemoth has a terminals for the live wire, the neutral wire and ground which is why I have this three prolg polrq behl. Which is why I have this three-pronged plug. So this three-pronged plug goes to one of those computer plugs you use for maybe your laptop charger or your PC. The plug is kind of fraying off now though so I’m going to cut the plug off and attach wires to it that will go to the terminals on the power supply. Also this plug isn’t long enough…. Goodbye, plug. I don’t actually know what these wires mean. I’ll have to use my multimeter to check.

All I know is brown is live, and Tom Scott taught me that. The glue gun is hot! Let’s glue this. That looks good. Now I’ve just got to finish the rest of the wiring. But I figured out why. You know this cord I was using? This was taken from my dad’s old computer charger and it stopped working for a Reason, mainly the neutral pin wasn’t connected anymore. I don’t know how that happens, but it’s pretty annoying. So, I got myself this behemoth of an ancient 24 volt 1 amp power supply and I’m just gonna steal the plug from it. …

and I’ve got an extension cord here, and this is the moment of truth. Nothing’s happening. The extension cord was unplugged. I’m an idiot sometimes. let’s try this again. Light’s on! Oh jeez. Fit, plug, fit! There. Okay. See that light? that light is on! that’s a good thing. cool. Now I’m gonna unplug it and wire this in. Oh that’s cool! The light takes so long to fade because there’s big capacitors in there. The preceding shot was filmed using the finished power supply. It was also intended to indicate that this is several weeks later than the rest of the video because I experienced technical difficulties and was an idiot. Here’s the deal. This motor controller is kind of… bad.

When there’s no load on the output 10:56 - circuit, the voltage across the output pins doesn’t change at all, so I was measuring it with my multimeter and turning the dial all the way around and not seeing any difference so I just thought this was a dud. Then I realized you needed a load, and when you have a load on it it does actually change the speed of your motor, but it’s still not great because first of all, the low end of the range is about 1.1 volts so some motors just won’t stop. Like this one, for example. If you turn it on and then turn it all the way back down it just kind of… goes… slowly. But the other problem here is that the actual modulation of the voltage is coming from the negative pin, which means that this voltage gauge, which is looking for a positive voltage, is no help at all. Right now, this is at its minimum voltage but the gauge says it’s at its maximum because it’s getting a negative voltage instead of a positive one.

So, overall I 12:06 - give this project about a 2 out of 10. It’s just not that great. The voltage range and the lack of a good voltage display just isn’t that practical for the sort of things that I expected to be able to do with this. I think it is still a promising concept, using the AC to DC adapter and DC motor controller to get a range of voltages, just this motor controller is kind of a piece of crap, so I might replace that and get one that’s better, but for now, I’m the Summoner of Robots, thank you for watching, and have a good day. Okay, I’ll stop. That’s probably not good for the motor. .