Whatever distance (while using whatever wire diameter) that will maintain minimum HC-SR04 Vcc (4.5 to 5 VDC), and appropriate trigger and echo pulse voltage levels delivered to and from the uC in use.
I know from experience that 50' of 4 wire, 24ga copper telephone cable works fine.
If you use screened cable you'll get at least 10 metres, assuming your in a electrically quiet environment.
If you want to go a real long way program a pic to handle the sr04 and transmit data via rs232.
Hi,
The length of wire will not matter the timing issue.
anyway, i will use this sensor for water level control in tank feed back from sensor and turn on/off electric motor control.
So, I think for this it will not matter and what you guys think for this project the LCD is displaying all data, I need to make Cover of this Box so, pls tell is there any idea to make it professional look and have a good sale in market.