Electronic Projects

       This project is an extension to two-phase  Unipolar Stepper motor interfacing with AT89C51 using IC L293D .  In the previous project, transistor switches were used to interface the stepper motor with the microcontroller.         Stepper motor is a variable reluctance DC motor.  When correct input sequence of signal is given to  the motor, it starts rotation in steps.  (For more detail refer Unipolar Stepper motor interfacing with microcontroller AT89C51). Note: Stepper motor is a DC motor in which the rotor is made to rotate in steps of x- degrees, where x depends on the type of excitation. In this example we would be considering a simple unipolar stepper motor.   The conceptual model of the unipolar stepper motor is as shown below                  

The quiz buzzer systems are widely used in school, colleges and TV programs. The team which presses the buzzer earliest is entitled to give the answer. At times it becomes very difficult to identify which team has pressed the button when two teams press the buzzer within a very small time gap. In such cases the decision can be biased due to human intervention. The quiz buzzer presented here takes care of the aforesaid problem. This quiz buzzer disables the other inputs as soon as the first buzzer is pressed. This quiz buzzer can be used for a maximum of eight teams. It is build around 8051 microcontroller (AT89C51).