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johnsmith1212

Practical use of voltage divider

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hello,

I am stuck with a dilemma which might or might not have a simple solution.

more: giá chung cư 17 phạm hùng

I have a psu supplying 46Vdc

unofrtunately i need to step this down to several different voltages.
1) 14 to 20Vdc (best would be 16Vdc) to power a micro mainboard power supply thingy, using approx 100W
2) 12Vdc form as well a led strip, a fan, temperature sensors (LM35 i believe) and arduino atmega 2560 board
3) 5Vdc

so i was thinking (maybe wrongly) to use a couple of 100W resistors in series (5KΩ - 5KΩ - 5KΩ&2KΩ - 2KΩ) and use it as voltage dividers.

if I calculate correctly this should give me
2/19 * 46 = 4.8Vdc
5/19 * 46 = 12.1Vdc (2 times)
7/19 * 46 = 16.9Vdc

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so going from the assumption that all this above is correct, i started to wunder if the is a problem when there is a big difference in power consumption between the different voltages. as the 16.9Vdc "rail" would use approx 90-95 Watt (also pushing to the limits of the resistors used) and approx 1A for the 5Vdc "rail"

if this is not a usable option.. is there an other way to do this correctly?
i have a step down board but this one has a max. input power limit of 40Vdc, en even though i swapped the capacitors to larger once i believe that the actually limit is defined by (an) other component on the PCB, which i would blow up. specially as it would be on 24/7

also voltage regulators can supply this power..

any advice would be highly appreciated.

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ps: i understand i faultly use term rail here., and no a different PSU is not an option!

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How about 3 terminal adjustable voltage regulators?

see for example: https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/LM317AHVT?qs=%2fha2pyFadugRpOCsw7uJG%2fYkcWjLe5SQfHkipQZSRvGAuHf8Q8Z20lpgQCwyK1vllMxUP7WNhWIGj0RAnAK1dQ%3d%3d

60 volts max and 1.5 amperes. Poke around at Mouser for higher current ones also. There are filters on their site that are helpful.

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