- Circuitry Background
Arduino
Relay Board
Power Supplies
Arduino
Relay Board
Power Supplies
- The Application of Circuits in our Project
The first section consists of the Arduino Uno (the microcontroller used in the design). The Uno can only output at a maximum of 5V with a maximum load of approximately 250 ma. Each of the solenoids operate at 12V and draw approximately 1-1.2 A when fired, necessitating a secondary power supply. Therefore the Arduino is used instead as a switch; providing 5V logic that is used to cycle the coils in the relay board when the code was run. The arduino itself is powered by a separate 5V power supply.
The circuit used to control the push solenoids and the solenoid valve is implemented in two separate sections; a microcontroller section and a relay section. The circuit was designed in the way because of the limitations imposed by the microcontroller itself.
The first section consists of the Arduino Uno (the microcontroller used in the design). The Uno can only output at a maximum of 5V with a maximum load of approximately 250 ma. Each of the solenoids operate at 12V and draw approximately 1-1.2 A when fired, necessitating a secondary power supply. Therefore the Arduino is used instead as a switch; providing 5V logic that is used to cycle the coils in the relay board when the code was run. The arduino itself is powered by a separate 5V power supply.
The second section of the circuit consists of the relay board and the solenoids. The relay board was an 8-channel board that allows us to run our solenoid valve and 7 additional push solenoids off of 12V. On the back end, the Arduino is jumped to the input pins on the bottom. When 5V is sent to these pins, the relays switch the common contact from the normally closed contact (NC) to the normally open contact (NO) which completes the circuit. Each of the relays require ~76 ma of current to cycle, which far exceeds the capabilities of the uno, so a dedicated 5V, 1.2A power supply is connected to the board to compensate. On the relay end, the positive wire of a 12V, 10A supply is connected to and strung across each of the NO contacts on the channels. The positive wires of each of the solenoids are connected to the common ports on the channels. The ground wires are all soldered in parallel and are wired back to the ground of the 12V power supply.
When everything is powered, the Arduino provides 5V logic to the board, which connects each respective common contact with the NO contacts, completing the solenoid circuit and firing them.