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I am trying out online tutorial to practice python and Raspberry Pi. I am currently following this tutorial.

It says a potentiometer is needed, but I don't have one. The lcd I have is JHD162A

What will happen if I connect the circuit exactly the same but without a potentiometer? Will it destroy my Pi or will it not work?

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  • \$\begingroup\$ Just get a pot or steal one - I've seen LCDs totally blank without one. \$\endgroup\$
    – Andy aka
    Mar 3, 2014 at 19:36

3 Answers 3

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The potentiometer sets the Voltage to the Contrast of the LCD.

You could replace the potentiometer with two resistors. See the diagram. One from 5V to pin3 of the LCD and the other from pin3 to pin1. Equal values of about 4.7k might be a good starting point.

enter image description here

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The potentiometer is used to control the contrast of the lcd. Without it it shouldn't cause any problems but it could be unreadable. You could use a fixed resistor instead, though you would need to experiment with the size to give you a readable display.

Something around 5k6 would be a good starting point, connected between the +ve supply and pin 3 of the LCD.

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Leaving out the potentiometer will not damage your processor or the LCD.

The potentiometer adjusts the contract of the LCD. If you leave the contrast adjustment pin unconnected, you might have a wrong contrast. Without the adjustment, the LCD could be all blank (white letters on white background), or it could be all black (black letters on black background). You may end up with the LCD, which is not readable.

P.S. A while ago, I went through the exercise of connecting the contrast pin incorrectly. Here's the thread. At first, I thought that this is a firmware problem. The realization that the contrast pin was the problem is in the last couple of posts in that thread.

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