ESP8266 Community Forum

- Fri Aug 07, 2015 4:52 pm #25312 Aah ?
I could use the same batterie for the Arduino UNO and the ESP ?
For now, I use a 9v pile battery (not enough, I know). I can use it like that ? ( http://prntscr.com/822nzm )

- Fri Aug 07, 2015 6:24 pm #25316 Your diagram is correct ... you just need to make sure that the correct voltages are applied. You must NOT attach a 9V battery directly to the ESP8266 ... it is a 3.3V device. You would use a voltage regulator to scale down the input voltage to be 3.3V.

An example of of such a device would be the LM317 ... see:

http://www.ti.com/product/lm317

Free ESP8266 book available for download here.

- Fri Aug 07, 2015 6:34 pm #25317 Okay, thanks !
I have this one : LD1117AV33 - It works ?
I see "Adjustable", what does it mean ? How can I make it delivering 3.3v ?

- Fri Aug 07, 2015 6:58 pm #25318 The V33 in LD1117AV33 means it is already 3.3V by default.
The A means "adjustable" by tweaking the common pin to higher level instead of connecting it GND.
(an example is that if common pins is at 1.7V, the output will be 1.7V + 3.3V = 5.0V)

Beware that using a 9V battery with LD1117AV33 will provide only ~33% efficency, 66% of heat, your battery will be discharge quickly. Use multiples AA in series or use a DC-to-DC converter for better efficiency, there are cheap on eBay.