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Topic: LCD contrats variable resistor issue (Read 886 times) previous topic - next topic

Laudan

Hello,

I am an arduino beginners ... first starter kit received end of last week.

I'v try to use an 16x2 LCD display.

I did connect a variable resistor to adjust the contrats but when I get a correct contrasted screen, I see some smoke from the resistor ... :smiley-eek-blue:

It looks like a shortcircuit ? When the resistor is near to 0k ??? I don't understand.
I did try with a 5k var resistor and a 2,2k resistor in serial between 5V and 1 of the 3 pins of the var resistor ... It does not work  :~ :~ :~

Can someone help me please ?
Thx

marco_c

Did you connect one end of the resistor to gnd, the other end to 5V and the wiper (the one in the middle usually) to the input for the LCD?
Arduino libraries http://arduinocode.codeplex.com
Parola for Arduino http://parola.codeplex.com

floresta

#2
Jan 28, 2013, 05:02 am Last Edit: Jan 28, 2013, 05:04 am by floresta Reason: 1
Except for his use of the term 'resistor' the description for the connections given by marco_c is usually correct since most datasheets call for the use of a potentiometer (a three terminal device) and not a variable resistor (a two terminal device) to control the contrast voltage.

If you were indeed using a potentiometer then you probably had the wiper connected to one of the power supply terminals and, as you adjusted the potentiometer you ultimately got a very low resistance across the power supply terminals, hence the smoke.


Don








marco_c

My bad on the name. Of course it is a pot.
Arduino libraries http://arduinocode.codeplex.com
Parola for Arduino http://parola.codeplex.com

Laudan

Hello

thanks for the quick answers.

My fault ... bad connection on the breadboard ...

And yes it was a potentiomètre.

my apologize :*

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