Hi
I have got this TDS sensor that I am using with a LCD screen, for some reason when I put the TDS sensor in a very salty cup of water the number of minerals is lower than when I put it in a normal cup of tap water.
This doesn't make any sense to me, does anyone have any ideas?
More info needed. Post links to as much info as you can find for your sensor. Post your sketch and what Arduino you are using.
Hi, @chris_c0des
Welcome to the forum.
Please post a link to data/specs of TDS sensor.
Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
Can you please post your code in code tags?
Thanks.. Tom.. 
Are you operating within the limits ? for example the probe can not be left too close to the edge of the container, otherwise it will affect the reading.
Show us your code, the circuit and a link to the TDS Sensor you are using.
please edit your post and add code tags...
(please read How to get the best out of this forum and post accordingly)
Sorry this is my first time using this forum.
For the power supply I am using a 1.5A mains power adaptor.
I have an Arduino mega Board.
This is the link to my TDS sensor ( Arduino with TDS Sensor (Water Quality Sensor) | Random Nerd Tutorials )
#ifndef LiquidCrystal_h
#define LiquidCrystal_h
#include <inttypes.h>
#include "Print.h"
// commands
#define LCD_CLEARDISPLAY 0x01
#define LCD_RETURNHOME 0x02
#define LCD_ENTRYMODESET 0x04
#define LCD_DISPLAYCONTROL 0x08
#define LCD_CURSORSHIFT 0x10
#define LCD_FUNCTIONSET 0x20
#define LCD_SETCGRAMADDR 0x40
#define LCD_SETDDRAMADDR 0x80
// flags for display entry mode
#define LCD_ENTRYRIGHT 0x00
#define LCD_ENTRYLEFT 0x02
#define LCD_ENTRYSHIFTINCREMENT 0x01
#define LCD_ENTRYSHIFTDECREMENT 0x00
// flags for display on/off control
#define LCD_DISPLAYON 0x04
#define LCD_DISPLAYOFF 0x00
#define LCD_CURSORON 0x02
#define LCD_CURSOROFF 0x00
#define LCD_BLINKON 0x01
#define LCD_BLINKOFF 0x00
// flags for display/cursor shift
#define LCD_DISPLAYMOVE 0x08
#define LCD_CURSORMOVE 0x00
#define LCD_MOVERIGHT 0x04
#define LCD_MOVELEFT 0x00
// flags for function set
#define LCD_8BITMODE 0x10
#define LCD_4BITMODE 0x00
#define LCD_2LINE 0x08
#define LCD_1LINE 0x00
#define LCD_5x10DOTS 0x04
#define LCD_5x8DOTS 0x00
class LiquidCrystal : public Print {
public:
LiquidCrystal(uint8_t rs, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
LiquidCrystal(uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
LiquidCrystal(uint8_t rs, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3);
void init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);
void clear();
void home();
void noDisplay();
void display();
void noBlink();
void blink();
void noCursor();
void cursor();
void scrollDisplayLeft();
void scrollDisplayRight();
void leftToRight();
void rightToLeft();
void autoscroll();
void noAutoscroll();
void createChar(uint8_t, uint8_t[]);
void setCursor(uint8_t, uint8_t);
virtual size_t write(uint8_t);
void command(uint8_t);
using Print::write;
private:
void send(uint8_t, uint8_t);
void write4bits(uint8_t);
void write8bits(uint8_t);
void pulseEnable();
uint8_t _rs_pin; // LOW: command. HIGH: character.
uint8_t _rw_pin; // LOW: write to LCD. HIGH: read from LCD.
uint8_t _enable_pin; // activated by a HIGH pulse.
uint8_t _data_pins[8];
uint8_t _displayfunction;
uint8_t _displaycontrol;
uint8_t _displaymode;
uint8_t _initialized;
uint8_t _numlines,_currline;
};
#endif