How to produce multiple DC voltages for a single project

Question

So the title pretty much says it all, but for an example, I have an arduino board, 5-12 V, an LED bank 18 V, and an ultrasonic mister 24 V.

I know some brute force methods to power them from one outlet, but I was wondering if there is a more elegant way to get the voltage for each device with only one transformer instead of three. The solutions I've come up with are less than elegant, and only moderately compact.

I was just wondering what solutions you guys have employed and hoped I could find something helpful.

Answer 1

First you want to take a regulated 24V supply. To that you want to add a switch-mode ("Buck") regulator to drop you down to 5V. You don't want to try using an LDO for this unless you are happy to have a heat sink the size of a small car. A good cheap choice is a "UBEC" that can take 24V in and give 5V out (I use these).

That 5V can then be fed direct into the Arduino.

Depending on what the "LED bank" is you may get away with an 18V (or adjustable) LDO, or an adjustable buck regulator. Or a simple (though high wattage) resistor may be all that is needed. You will have to provide more detail on this to get more help.

Answer 2

Typically you'll only have a single transformer in this sort of design, to get you down to your highest DC voltage. Then you'll create lower voltage rails from that. You can use any number of approaches depending on your needs, e.g. capacitive dropper (on the 24Vac output of the transformer), resistor divider (on your rectified 24Vdc).

But, most typically for hobbyist projects you'll want to be using a regulator IC, either a linear regular/LDO (low noise but poor efficiency) or a separate onboard SMPS IC (good efficiency but typically noisy).