Voiltage divider to power Arduino, doesn't work?

Forum 2005-2010 (read only) Hardware Interfacing
1

I'm trying to power an arduino with 3.3v through a 5v supply, which seems should be done with a voltage divider, but when I connect the divider - 1k and 2k resistor in series, with +5v on the leg of the 1k and Ground on the leg of the 2k to make 3.3v in the middle, it gives a good 3.3v until I connect the arduino - then 3.3v drops to a minimum level... am i missing something?
1k____2k
| || |
o o o
5 3.3? G

2

am i missing something

Ohm's Law? :wink:

3

Yes but ehh..

4

What's now in parallel with your 2K resistor?

5

Hmm not sure if I understand that question or phrasing, but this:?

1k____2k
| || |
o o o
5 3.3? G
| |
o o
Ard+ Ard-

6

That's right, your Arduino is in parallel with the 2K resistor.
What does that make the value of the lower leg of the voltage divider?

7

sorry, do you mean what voltage it gives? (im giving away my beginner level)

8

You already know what voltage it gives:

then 3.3v drops to a minimum level

Sorry, I just noticed this:

which seems should be done with a voltage divider

Who told you that?

9

Ah you mean Im completely on the wrong track and a voltage divider can't be used to supply? That would answer a few lost hours but leave the question; how would I reduce a 5v power supply to 3.3v to power an arduino?

10

how would I reduce a 5v power supply to 3.3v to power an arduino?

Use a 3.3vdc voltage regulator, 5vdc in 3.3vdc out.

Or wire enough series diodes between the 5v and 3.3v load to drop the voltage to 3.3, each diode drops about .6vdc

Lefty

11

cheers lefty! will try

12