How to properly connect two different devices to the same power supply?

Question

Power Supply

I am detailing my question:
1. Power supply (laptop) with parameters: 19V, 4.7A.
2. According to the documents, the 1st device is powered by a power supply unit with the following characteristics: 12V, 4A.
3. According to the documents, the 2nd device is powered by a power supply unit with the following characteristics: 5V, 3A.
Does it make sense to connect all this to one power supply? (In terms of labor costs - soldering, assembly, etc.)

Answer 1

As already mentioned, you need to make 2 additional converters 19DC-> 12DC with a power of 4 amperes (or higher) and 19DC-> 5DC with a power of 3 amperes (or higher).
The output power of the original block is 90 watts. The power of the first converter is 48 amperes, and taking into account the conversion efficiency 48 / 0.8 \u003d 60 watts, the power of the second is 15 watts, and taking into account the efficiency - 15 / 0.8 - 19 watts.
In total, both of them will consume about 80 watts from the first power supply at maximum load (and manufacturers of target devices select them with a margin), which is less than 90 watts of the maximum capabilities of a laptop power supply. On the other hand, this is true if the efficiency of DC-DC converters is 80 percent or higher (if they are switching, transformer converters are less efficient).
From devices - take 4 of these and parallel them (3 to 12v, 1 to 5v)www.electronshik.ru/item/dc-dc-power-module-25w-1077766
www.electronshik.ru/item/kit-pw24-1-3-1334161 (these need more)
www.electronshik.ru/item/kit -pw821-1928080 (these need less)
www.electronshik.ru/item/kit-pw841-1928121

Answer 2

Attaching two adjustable switching DC-DC buck converters is not difficult. Power reserve is available.

Answer 3

Maybe it's easier for you to take ATX: there is just what you need.

Answer 4

If you want to figure it out, then read the allowable limits of the supply voltage for the first and second devices.
if you can, then look at the datasheets on the input converters, then you can definitely say whether they will survive or not.

Answer 5

Taking into account your clarification in the comment - no, PMSM, it’s not worth using a laptop PSU for such a thing, you need to find a PSU that immediately gives out 5 and 12. Perhaps you are leaning towards a laptop one because of its compactness - then the PSU from a desktop computer will be too big for you . But there are "slim" class computer cases, they have their own PSU sizes, much more compact than usual ones - that's what you should look for. In terms of voltage, they are equivalent (there are 5, 12 and everything else), and in terms of current / power, they are two to three times weaker than usual (I came across 125 and 150 watts - this is more than enough for your loads).
At the same time, it should also be borne in mind that with a common power supply, the negative line will close the metal cases of both loads between themselves (if they have such cases, and if they are connected to the power minus - and this happens very often).