Go Down

Topic: Arduino pro mini supply (Read 2175 times) previous topic - next topic

Yaro

I want to supply arduino pro mini 5v with a 9v battery. I'll use it to sample an analog signal. Do i need to use some filters or anything else? I would like that the sampling will be accurate.

Thank you.

CrossRoads

Nope. Battery is like a big capacitor, smooths voltage pretty good by itself.
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.

cmiyc

Yes, you'll want some small cap values to filter out high frequency stuff.  Like 1uF, 0.1uF ceramics.


Nope. Battery is like a big capacitor, smooths voltage pretty good by itself.

No batteries are like very bad capacitors, not big capacitors.  They are very very slow to respond to signal changes.  You still want something small in front of them to help with ripple.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

CrossRoads

Well, he's got the onboard regulator and its capacitors and the other caps that go with the uC.
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.

fungus


No batteries are like very bad capacitors, not big capacitors.  They are very very slow to respond to signal changes.


True.


You still want something small in front of them to help with ripple.


The power will go through a regulator on the Pro's PCB. Adding decoupling before the regulator won't do very much.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

Yaro


Yes, you'll want some small cap values to filter out high frequency stuff.  Like 1uF, 0.1uF ceramics.


Nope. Battery is like a big capacitor, smooths voltage pretty good by itself.

No batteries are like very bad capacitors, not big capacitors.  They are very very slow to respond to signal changes.  You still want something small in front of them to help with ripple.

0.1 tantalium between + and - of battery is enough?

cmiyc


0.1 tantalium between + and - of battery is enough?

No, you wouldn't want to use a Tantalum, even if you could find one that was only 0.1uF.

As the others point out, the pro mini has its own decoupling solution.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

jack wp

Well, now I am all confused. LOL
How accurate of a reading do you need?
What voltage range are you reading?
Are any other devices being run from this battery?
What kind of battery, and how long do you think it will last?

xl97

#8
Aug 02, 2013, 04:51 pm Last Edit: Aug 02, 2013, 05:18 pm by xl97 Reason: 1


0.1 tantalium between + and - of battery is enough?

No, you wouldn't want to use a Tantalum, even if you could find one that was only 0.1uF.


* not in conjunction with the pro-mini project....but a more general question

but why would one not want to use a 'tant' polarized cap for the decoupling on the power rails?

(curious to learn is all... is it because of the argument that it may 'blow' in a shorted position?)

thanks!


also..

SMD TANT CAPS:

0.1uF
http://www.digikey.com/product-detail/en/TAJR104K020RNJ/478-3286-1-ND/930078

1.0uF
http://www.digikey.com/product-detail/en/298D105X0016M2T/718-1157-1-ND/1559651

10uF
http://www.digikey.com/product-detail/en/TCM0J106M8R/511-1494-1-ND/1209671

22uF
http://www.digikey.com/product-detail/en/F980J226MMA/493-2876-1-ND/1129165

jack wp

If the only thing this 9V battery is powering is the pro mini, then there is no need for any other caps.
But we don't know yet, because the OP has not answered that question (or others ask of them) yet. Maybe today.

Go Up