Projects

This system employs various circuits and components that control the start and end of a marble roller coaster. Essentially, after a correct combination is entered, a solenoid fires and pushes a ball down the roller coaster. When the ball triggers a metal detector, this causes an electromagnet to deactivate, dropping another ball into a cup.

How It Works

Below is a high level, block diagram of the system.

Piano Input - Allows signals to be sent from the capacitive piano to the corresponding circuit. Has 4 pads and uses a 5 note combination.

Capacitive Piano Circuit - Sends signals from foil pads to Arduino #1.

Arduino 1 - Processes signals from the piano circuit and sends signals to the buzzer.

Strobe Light - Lights up a strobe light after receiving 9 volts from a battery.

Light Detector - Uses a photoresistor to detect light from the strobe light circuit. Uses potentiometers to determine light sensitivity. Triggers a relay to send 6 volts to a solenoid, which pushes the marble down a marble track.

Metal Detector - uses an inductor coil to sense changes in magnetic field. The change is represented as a frequency using the 555 timer and sent to Arduino #2.

Arduino 2 - processes the frequency from the metal detector by converting it to a PWM value. Compares the PWM value against a set threshold to control the FET output that powers the electromagnet.

Electromagnet - uses an FET to drive an electromagnet. It is demagnetized when it doesn’t receive a “high” signal from the Arduino. When demagnetized, the electromagnet releases a metal ball into a cup.