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### Topic: power: 5v and 3.3v, using voltage regulator (Read 1 time)previous topic - next topic

#### nym

##### Jun 01, 2011, 11:05 pm
hey, i have a simple question regarding power and power source.

so the arduino lets me send 5v to my sensors.
i am using the PIXART infrared sensor from the inside of a wiimote.
it needs 3.3v. i have built a regulator that powers the sensor from USB power (5v of course) regulated to 3.2v.

now, my question is, can i use the same regulator circuit to convert a branch of the voltage from arduino down to 3.2v for use with the PIXART while using the unregulated 5v from arduino on other sensors?

i image the answer is yes, but the reason i ask is because of ground - since ground is the comparison, does it matter if the upper threshold (3.2v, 5v) is different for different parts of the circuit??

nym

#1
##### Jun 01, 2011, 11:12 pm
You need the grounds all tied together.

The arduino boards can output 3.3V (at differing mA capabilities), how much current are you using?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### James C4S

#2
##### Jun 01, 2011, 11:24 pmLast Edit: Jun 01, 2011, 11:26 pm by James C4S Reason: 1
Quote
so the arduino lets me send 5v to my sensors.

Voltage isn't sent.  It is a potential that is provided.  Current isn't sent either, it flows.

Quote
does it matter if the upper threshold (3.2v, 5v) is different for different parts of the circuit

If it mattered, almost no electronics would work....

Ground isn't really a "comparison", it is the "reference."  All components need to have a "common" "reference" (quotes added because those are other words for "ground").  Ultimately you are trying to make current flow between a higher potential and a lower potential.  To make life easier, we commonly call that lower potential "Ground."

So if your regulators and all components they are connected to share the same ground (reference), current will flow.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

#### nym

#3
##### Jun 01, 2011, 11:40 pm
excellent, thank you.

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