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# How to reduce voltage from 24V to 12V and 5V? Answered

I have a power supply with output of 24V, 1A. I need to reduce the voltage to 12V to power a water pump and to 5V in order to power an Arduino and an air pump.
Can I just create a voltage divider using resistors for this?
The water pump has an input of 12V, 5W.

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## 7 Replies

seandogue (author)2017-10-03

Presuming the source voltage is DC, DC/DC converters. Simple linear converters (78xx) are unlikely to provide relief as they'll likely overheat. Switching converters are your best bet. Skip the voltage dividers. they can only source voltage (ie as a rough-shod voltage reference) since loads reduce the effective R2 (lower leg of divider) in the R2/R1 multiplier for

Vout = Vin x R2/R1

seandogue (author)2017-10-03

(That is, a load connected to the output of a voltage divider needs to have very high impedance to ameliorate the affect, and high impedance means low current from a fixed source voltage)

-max- (author)2017-10-02

Voltage dividers are not usable for power applications like this. Because if you connect any load resistance, then that load resistance is in parallel with one of the resistors in the divider, and the voltage sags. Also lots of power is wasted as current goes positive to ground directly and is waste

Instead you want voltage regulators. Amazon has a lot of buck converters that are cheap and adequate for your application.

MichaelJ299 (author)2017-10-01

Note that though the logic on Arduino is 5v, most boards prefer to have 9V or even more as their power supply. 12V should be fine in most Arduinos

steveastrouk (author)2017-10-01

If you want efficiency, get some buck switching regulators on Ebay.

DON'T use a voltage divider - you will have an output that varies with load and if you are running a pump, it will be bad for it. Your logic circuits won't like "5V" that varieseither.

iceng (author)2017-10-01

+1

rickharris (author)2017-10-01

ac or dc