SCHEMATIC:   PARTS LIST: ARDUINO NANO HC-SR04 potentiometer tip120 Darlington transistor speaker ARDUINO CODE: #define trigPin 9 #define echoPin 10 long duration; int distance; int val; void setup() { pinMode(trigPin, OUTPUT); pinMode(echoPin, INPUT); } void loop() { val = (analogRead(A1)); … Continue reading Arduino Mad Scientist Laboratory EP# 1 Ultrasonic Tripwire Alarm