thaks for your reply georgina,
My Arduino is an Arduino Uno.
I'm totally new about Arduino and electronics so, i prey you to e patient with me.
Let me tray to explain: on the datasheet of the Ultrasonic sensor (the Daventech SRF04) they say that the avarage consumption is reasonable at less than 50mA and typically about 30mA. I know (is it real?) that Arduino can give a maximum of 20mA current from it's output pins.
Because of my complete "ignorance" in the field of electronics, I do not know how to behave. I do not know how to physically connect the two devices together.
The fact that the consumption of current by the sensor differs from the current maximum capacity supplied by Arduino is a problem? how to fix it? what is the wiring diagram of the configuration?
Probably i'll connect the ground of the sensor with the ground of the microcontroller, the "Echo Pulse Output" pin of the sensor to any Arduino input, but then? I'm in doubt on these other links:
connect a digital output of the Arduino to the "trigger pulse input" of the sensor and then connect the 5V Arduino pin directly to the sensor. The latter two must be operated in a direct way? resistance needed to be placed? need to study a different circuit configuration?
thank you so much