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1  Development / Other Software Development / Re: Class for both DHT11 and DHT 22 (temperature & humidity) on: February 13, 2012, 02:45:13 am
Hi Rob,
Thank you so much for writing such an easy to use library!
I wanted to ask you a question if I may -
I'm using the DHT-11,
I tried supplying it with different voltages (3V, 3.3V, 5V - using the
Arduino Uno's 3V,5V and the Arduino Fio's 3.3V power supply)
and for each voltage there are different readings for the temperature and humidity (a
very big difference between 3V and 5V).
what is the correct voltage that it should be supplied with?
(or  is there a way to work around this?)
according to the datasheet it can be supplied with 3V - 5.5V.

thanks!
2  Forum 2005-2010 (read only) / Interfacing / Re: Arduino +Sparkfuns 4-digit 7-segment 16pin display on: July 12, 2010, 11:02:03 am
just a quick comment.
4 resistors are enough, and the 40ma is not a real issue (only 4 segments can be using the same current source, and with 10ma you can still get good brightness) if using the code from "http://nootropicdesign.com/projectlab/2009/10/"
(mentioned by jeremytsl).
in this code the relevant segments are turned on individually, and stays on for a short delay, and then turned off. this also answers the question embedded in the code for why there is a need for a delay.
"delay(1); // Don't understand why I Have to set a delay
 digitalWrite(groundPins[g], HIGH);"
also, if using the red 7-segment display, which is rated 2.1V and 20ma a 330 or 220 Ohm resistors are better.
if using a code that lights all the segments in a number at the same time - then the comments are accurate and segments should each have a resistor and 40ma Arduino pin output should be taken under consideration.
thanks everyone for your comments!

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