100 V DC power supply from serial laptop PSUs - maybe?

Question

Electronics

Requires a DC power supply with a voltage of about 100 V, the current through the load is about 20-30 mA (ie load resistance 3-5 kOhm). As cheap as possible. What happens if you take 5 laptop power supplies, say, 20 V and 65 W each, and connect their outputs in series?

Answer 1

There may be a problem due to the fact that such power supplies do not have galvanic isolation. I would not recommend such a solution. Either it will work, or it will bang - one of two things. Although the third option is also possible - it will bang, but not immediately. It strongly depends on the scheme of specific PSUs (and what scheme there will be is not known). If you are still going to collective farm like that, then be as careful as possible. The electrical panel must have a working RCD or differential automatic. Under no circumstances should it be left unattended.
The normal option for you is a transformer PSU. Moreover, you do not need voltage stability, you need a simple circuit - a transformer and a diode bridge, to adjust the current at the output, a variable resistor in series with the load. The main thing is that such a PSU will be safe (transformer = galvanic isolation).
Upd. here is an interesting article about electrical safety: https://habr.com/ru/post/427195/ and continued: https://habr.com/ru/post/428023/

Answer 2

Yes, no one forbids. These are normal power supplies.
And what kind of device is 100 volts at such a low current strength?

Answer 3

Maybe.

Answer 4

STEP TRANSFORMERS 220/100 JAPAN

Answer 5

And the block with Aliexpress will not work?There is also a 100V model in the line.
I do not think that it is more expensive than 5 power supplies for a laptop, but there are current and voltage adjustments.