Hand Crank Generator for Cell Phones

1
Hand Crank Generator for Cell Phones

• Team 18
• Adam Weber and Robert Dunn

2
Introduction
Charge a cell phone
Power an LED flashlight
3
Objective

• Our goal was to design a portable hand-crank
  generator for use in emergency situations. The
  generator can provide enough power for a short
  phone call or for a couple minutes of LED light.
• The generator can use adaptor tips
• to power several different brands of
• cell phones, such as Nokia, LG,
• Sony/Ericcson, Samsung, and
• Motorola.

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Original Schmatic
5
New Schematic
6
PCB
Current Limiting Circuit
Switch
LED
Ultracapacitor
DC output jack
Voltage Regulator
Smoothing Capacitor
Rectifier
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Motor Selection
F series Minertia Motor 12 Volts DC Yaskawa
Electric Corp.
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Motor

• PittMan Motor
• Model GM9434G807
• 12 Volt DC, 65.51 gear Ratio
• 65.51207860 rpms so we can turn a little
  slower than 2 rpms

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Motor PerformanceCell Phone as Load
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Motor PerformanceLED as Load
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Power Circuit

• Rectifier allows the motor to be turned both
  directions.
• Regulator supplies constant 5 volts to the
  circuit with an unstable input voltage.

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Motor Voltage and Voltage Regulator Output Voltage

• Bottom Channel 1 Motor output voltage
• Top Channel 2 output of voltage regulator.

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Charging the Capacitor
LED as the Load
Cell phone as Load
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Ultracapacitor

• Stores charge from the generator
• Keeps output current steady for any sudden
  drops in input current
• Temporarily provides power to phone and LED
  after cranking is stopped
• 5 Volts, 1 Farad

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Current Limiting Circuit

• Active current limiting circuit
• Load voltage is constant when current does not
  exceed max
• Transistors act like switches, current flows
  when base voltage is high
• When below max current, Q1 base current is high
  enough to allow current through
• Value of Rsense is small so there is little
  voltage drop
• When current approaches max, the voltage drop
  across it causes Q2 to turn on
• Current routes through Rbias and Q2 causing
  less voltage across Rsense.
• Q2 shuts off, causing a voltage increase across
  Rbias and Q1 turns on

http//vidisonic.com/2008/07/10/current-limiting-c
ircuit/
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Current Limiting Circuit
http//vidisonic.com/2008/07/10/current-limiting-c
ircuit/
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Current Limiting Circuit
Current vs. Generator Output Voltage
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Current Limiting Circuit
(mA)
5V
Current vs. Voltage into cell phone
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Efficiency of the Cell Phone
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Efficiency of the LED
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Results
Cell Phone
LED
Test done with 2 minutes of cranking 5 test total
Test done with 30 sec of Cranking 5 test total
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Machine Shop

• Hand crank
• Protective case
• 4 x 3.5 x 3 inches
• Mounted circuit board inside

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Electronic Shop

• Provide Parts
• Helped find Parts
• Helped with PCB board creation
• Printed PCB board

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Recommendations

• Smaller motor
• PWM/Buck Converter to regulate voltage
• PCB board with non-conductive surface
• Possible power meter
• Reflective background for LED

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USB Support

• Many new phones such as the iPhone charge using
  USB
• USB uses 5 Volts
• Have to use a separate DC output jack

http//www.thecodecave.com/images/usbcable/usbconn
ectorpinout.png
http//www.rca.ac.uk/UploadedImages/apple-iphone-i
n-hand-thumb.jpg
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• Questions?