The base unit houses an Arduino board which polls the buttons to see which is pressed first. The LED on the appropriate buzzer box is illuminated so the players know who got in first. One special ...

As this happens, the transistor T1 (as shown in the schematic) stops working and transistor T2 starts working and starts off the buzzer. Sensitivity of the sensor can be set by changing the variable ...

Code and schematic used to actuate a solenoid valve ... 5V for the Arduinos onboard ADC and a 5V relay used for the Arduino to switch the 12V solenoid valve. Melodic tones from a piezo buzzer provide ...