I've been shopping for components to build a bench-top DC power supply, much like the one built in Great Scott's video. I'm planning on using a LTC3780, which has an output voltage range around 0.8-30V and a current range around 0.8-6A. I would like this unit to be able to go to smaller current and voltage values in order to test small circuits (ie. 0-28V;0-5A), but I'm not sure what the right approach is. I thought about just using a resistor in series with the output lead, but from what I've read that that's not the way to go. Any help would be appreciated!
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Voltage is voltage. If your supply is set for 28 volts, it will provide 28 volts. The current setting is a limit, not a supply setting. That is, a 6 amp supply can provide 5 amps if needed, but it won't force 6 amps through a 5 amp circuit. So don't worry about the mismatch. If things were the other way around, for instance if your supply could only provide 5 amps but the load needed 6, you'd be in trouble.
So, the supply as specified will do just fine. Don't worry about it.
As a note after watching the video, a couple of points. 1) Don't use a pair of needle-nose to tighten nuts. Get a nut driver or adjustable wrench. 2) Do not get into sloppy habits about soldering like he does with his switch wiring. Always wrap the wire around the terminal you're soldering to. If you have to hold the wire while you're soldering, you're doing it wrong. The reason this is important is his power demonstration. Remember how the resistors just dropped off the wire when they got too hot? If something goes wrong and your switch wires get hot, you don't want them flopping around the inside of the box.
answered Mar 31, 2016 at 2:12
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\$\begingroup\$ I didn't watch the video, and I think its not a good video to watch either.... \$\endgroup\$ Commented Mar 31, 2016 at 7:12
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\$\begingroup\$ Too lazy to watch the video, but if you can show while working that things get too hot for solder, whatever part, then the design is very flawed to begin with. "I know this'll get hot in this specific case and I will not change the design." \$\endgroup\$– AsmyldofCommented Mar 31, 2016 at 7:14
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\$\begingroup\$ @Asmyldof - That's the problem with responding to a video you didn't watch - you get things wrong. The video is actually pretty good, and your criticism does not apply to it. \$\endgroup\$ Commented Mar 31, 2016 at 13:36
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\$\begingroup\$ I was a little afraid that might happen (though I recognise the name from a video I was extremely unhappy with, don't remember which), but I made the comment anyway. Think of it/me what you will. \$\endgroup\$– AsmyldofCommented Mar 31, 2016 at 16:41
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\$\begingroup\$ @Asmyldof - Don't worry. I forgive you. \$\endgroup\$ Commented Mar 31, 2016 at 16:42