PING-PONG SHOOTER

Goal

The Ping-Pong shooter, as its name , is able to shoot Ping-Pong balls, and the machine can simulate a real-world situation that if there is a player in front of it, it starts shooting; otherwise, it stops working. 

Criteria of Success 

Able to control the system intangible 

Able to control the machine i.e. control weather the ping-pong ball will shoot or not 

A machine that can shoot 

PERT Chart 

How It Works 

The Ping-Pong shooter mainly contains three parts. The first one is a switch which is made by connecting to a photoresistor. The second one is two DC motors to shoot the balls. The last one is a stepping motor.

Main component 

•Photoresistor 

•DC motor 

•Stepping Motor (28BYJ-48) 

•Microcontroller (89s51) 

•Octal high voltage high current Darlington transistor arrays (ULN2803) 

•Voltage regulator(L7805CT) 

ULN 2803 

•A ULN2803 is an Integrated Circuit (IC) chip with a High Voltage/High Current Darlington Transistor Array. It allows you to interface TTL signals with higher voltage/current loads. 

•The chip takes low level signals (operate at low voltages and low currents) and acts as a relay of sorts itself, switching on or off a higher level signal on the opposite side. 

L7805CV 

•Disadvantage: Input voltage always needs to be higher than the regulated voltage

•I.E. 7805 = 5V, 7812 = 12V 

•The 78xx family is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost .

Miscellaneous Component 

•Resistor (10k Ω *2) 

•Capacitor (33pF *2, 100nF *1 ) 

•Oscillator (12MHz *1) 

•Wires 

•PVC tube (2” Diameter) 

Schematic 

Function 1: Switch 

•Electronic switch on pin 9 (reset) of microcontroller 

•Using a photoresistor and a suitable resistor with voltage divider 

•Photoresistor: 

  Bright= Small resistance; Dark= Large resistance 

   Voltage out connect to pin 9 

•Pin 9: 

   High = turn off , Low = turn on 

Theoretical Calculation 

•Photoresistor: 1k ~ 14k Ω 

•R1, R2: 10k Ω 

•Vin : 5V 

On:

 

Off:

Analysis 

Light On 

Light Off 

Function 2: DC Motor (Shooter) 

Two DC Motors - one is spinning counterclockwise, and another is spinning clockwise 

Rubber on Cap to increase the friction between surfaces 

Function 3: Stepping Motor (Gate) 

•Brushless DC motor 

•Divide full rotation into a number of parts 

•28BYJ-48: 

• Four phases five wires 

•12VDC 

•1100 →0110 →0011 →1001 →1100 

•Advantage: Precisely control the position of rotation

Serial Programmer 

•Homemade programmer 

•Connect to print port 

To Control the Stepping Motor 

•Pre-programmed microcontroller 

Criteria of Success 

•1. A machine that can shoot ✓ 

•2. Able to control the machine i.e. control weather the ping-pong ball will shoot or not ✓ 

•3. Able to control the system intangible ✓ 

Cost 

•Home Made 

•eBay 

•Joola Joola iPong Topspin (Green) Table Tennis Ball Machine i0 

•$77.00 

•Conclusion: 

Cheaper to build than buy one Component	Price/unit
ULN2803	0.32
AT89S51	0.75
L7805CV	0.2
Oscillator(12MHz)	0.04
Laser Diode	0.99
PVC TUBE	3.00
Stepper Motor	0.40
DC Motor	0.00
Miscellenuos i.e. resistor, capacitor	0.05
Bread Board	1.67
Total	7.42