Hello everyone. I want to connect 3 HC-SR04 Ultrasonic Sensors to my Arduino Leonard and I want them to detect individually if there's something in front of them. My question is, is this the solution? I don't want to ruin anything with voltage. Sorry if the diagram isn't clear this is my first drawing. Thank you and have a nice Christmas.
Post a schematic, no Fritzing spaghetti diagram. Those are generally anywhere between useless and outright misleading. It's made even worse in your case by posting just part of it and in low resolution.
The best way is to give every trig and every echo their own pin; make sure you have the regular 5V version of the HC-SR04. Remember to allow sufficient time between readings to let echoes die out (about 10 ms should do) or that may give you stray readings as they may pick up the echoes from the previous reading (could be from another sensor even).
I tried to use circuit.io but no use. It didn't add the components to the client-side so I gave up. Thank you for your reply I will make the circuit according to your advice and use a proper schematic next time.
For making schematic diagrams, my favourite is KiCAD (free and open source). Very capable in drawing schematics and designing PCBs.
Another popular one is EagleCAD, which I understand is free but with limitations on the free tier.