Scratch Robots

1. Scratch Robots Motor Controller

2. When the light sensor sees black, the motor is OFF. When the light sensor sees white, the motor is ON Motor Controller Radio Shack Parts $ 9.00 – 1-1/8” Modular IC Breadboard $ 2.00 - IRF510 N-channel MOSFET $ 3.00 - Photo Resistors $ 3.00 - 22 Gauge Hookup Wire $ 1.50 - 10K Potentiometer $ 3.00 - 9V connector $ 2.50 - 9V battery -------------------------- $24.00 - Total Circuit Board www.build-it-yourself.com

3. Scratch Robots MOSFET Motor Controller Radio Shack Tools $ 9.00 – Test Jumpers $ 3.00 – Screw driver $ 7.00 – Wire Strippers $ 20.00 – Multimeter -------------------------- $39.00 - Total Tools www.build-it-yourself.com

4. Scratch Robots MOSFET Motor Controller +6V to 9V R1 Photo resistor 2K Ohms light (on) 50K Ohms dark (off) 5V to 9V DC Motor 1A G D R2 10K S www.build-it-yourself.com

5. Scratch Robots MOSFET Motor Controller +6V to 9V R1 Photo resistor 2K Ohms light (on) 50K Ohms dark (off) 5V to 9V DC Motor 1A Q1 IRF510 N-channel MOSFET 2V-4V GS trigger voltage 20V GS Max voltage 4A DS current G – Gate D – Drain S – Source G D R2 10K S If the voltage between the Gate and Source of this N-channel MOSFET is < 2 volts, no current can flow between the Drain and Source terminals. The motor will not run. If the Gate to Source voltage is > 4 volts, then current will flow between the Drain and Source and the motor will run. Adjust R2 so motor is off when R1 sees no light. The Gate voltage should be < 2 volts. When R1 sees light, its resistance should decrease raising the Gate voltage > 4 volts. Then the motor will run. Radio Shack Breadboard MOSFET On/Off Controller Build-It-Yourself www.build-it-yourself.com

6. Scratch Robots MOSFET Motor Controller Voltage Divider (FET Gate Bias Control) 9V VG 9V R2 R1+R2 = VG 9V 10K 4K(light)+10K VG = 6.4V R1 Photo Resistor = VG R2 Variable Resistor VG 9V 10K 16K(dark)+10K VG = 3.4V = www.build-it-yourself.com