This circuit aims to replace a traditional toggle switch for switching large amounts of current. Instead of the bulky and expensive traditional toggle switch, this circuit allows for a cheap pushbutton, and a few transistors and resistors to be used and have the same effect.

For my application, I wanted a way to have the circuit draw very little curren
t when in the off state, be able to be powered on with a pushbutton, and then turned off through software on the Arduino.
Here is the circuit diagram:

Here’s a video of the circuit in operation:

The code running on the Arduino is very simple:

int button = 3;
int led = 2;

void setup() {
  pinMode(button, INPUT);
  pinMode(led, OUTPUT);

  digitalWrite(led, LOW);
}

void loop() {
  if (digitalRead(button)) {
    digitalWrite(led, HIGH);
  }
}