I have an Arduino mega that is being used to control relays and ultrasonic sensors. The relays that I am using is a 4 DPDT Signal Relay Module Model: D-256 Series and the other is a 4 channel Single pole Relay for Arduino. I am only using 3 channels of each relay. At any given time I only output to 2 channels from each relay at a time. I tested the relay to ensure they worked with the Arduino and they ran fine.
Once I connected the Ultrasonic sensors to the board as well, the board would not power and the voltage regulator got extremely hot. I would assume the total current draw was too high from the outputs and VCC of the Arduino.
I think that if I take my 9V battery and run it through a voltage regulator 7805 then I can run the VCC power of the relays with the battery instead of the VCC from the Arduino. This would result in me only running a VCC to the 4 ultrasonic sensors, the triggers for the ultrasonics from the Arduino, and the output signals fora maximum of 2 channels per relay board resulting in 4 relays. Most of the time it is only 2 relays.
Would I be able to power the relay boards VCC with the 9V running through a 5v regulator instead of the arduino so that I can reduce the current running through the Arduino?