Thank you for taking your time to read my topic. I am building a device which will trigger when a cat passes and will not trigger when a human passes.
The Setup: For this I use 3 sensors, one photoelectric sensor and two ultrasonic sensors. The PE sensor is on cat-level and when the beam is broken the arduino will trigger a relay which has a solenoid valve connected to it. I use two ultrasonic sensors on human-level to "disarm" the system when a person passes and a bright LED will start blinking for 15 sec. As a power supply I use a 24V 1A supply. The sensor and the valve need 24V. I have a voltage regulator (pre-built) set to approx. 6 volts.
The problem: As soon as I plug in the power supply the disarm LED starts blinking, so my conclusion is that the arduino gets a signal seeming like there is an object infront of one of the ultrasonic sensors. However, I am quite possitive that I have rigged up the sensor correctly because when I unplug the power from the voltage regulator and use a separate source (power supply or computer USB) everything works like it is supposed to be. I can read the sensor distances on my PC and the status of the PE sensor and it triggers the relay when the beam is broken.
So I am really confused as of what is going wrong. The only difference I make is taking the power plug from the regulator out of the arduino and plugging in a "3rd party" plug then everything works.
Really hope someone can help me out. Thank you in advance!