Transcript The Battery Eater

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Introduction
Explanation of the circuit
Price breakdown
Construction notes
Distribute kits
Build time
http://www.nisk.k12.ny.us/iroquois/teched//Fall_Conference/battery_eater/battery_eater.htm
The Battery Eater
Giving old batteries a new life
http://www.nisk.k12.ny.us/iroquois/teched//Fall_Conference/battery_eater/battery_eater.htm
Joule Thief
Battery Eater
E
Hand-w ound
ferr ite torr oid
E
B
B
2N3906
47 uF
+
2N3906
C
10K
~ 0.3-1.5V
C
3 Volt LED
3 Volt LED
100K
B
LDR
+
47 uF
C
2N3904 E
• The Battery Eater is really two
Circuits in one
LED Flasher
The Joule Thief
• The Joule Thief uses a hand wound
transformer to increase voltage
How it Works: Joule Thief
• Voltage flows through the left coil, the resistor
limits current
E-
E-
EEE-
EEEEEEEE-
OFF
EEE-
E-
How it Works: Joule Thief
• The transistor turns on allowing a large
current to flow through the right coil
E-
E-
EEE-
E-
EEEEE-
E-
E-
E-
E-
E-
EE-
ON
EEE-
E-
How it Works: Joule Thief
• The current in the right coil induces a current
in the left coil which opposes its existing
current flow, shutting
EEEEoff the transistor.
EEEEEEE-
E-
E-
E-
E-
E-
EE-
OFF
EEE-
E-
How it Works: Joule Thief
• Current in the right coil cannot shut off
immediately leading to a bump in voltage
Small Voltage
as the field in the left
EEErise
EEcoil breaks down
EEEE-
EE-
E-
Field EE- breaks
down E-
EE-
E-
EE-
OFF
EEE-
E-
How it Works: Joule Thief
• This process repeats, and the voltage rises
E-
E-
Small Voltage
rise
EEE-
E-
EEE-
EEEE-
E-
EE-
Field
E- breaks
down EE-
EE-
OFF
EEE-
E-
How it Works: Joule Thief
• Once the voltage reaches the breakdown
voltage of the LED electricity can flow
E-
E-
Small Voltage
rise
EEE-
EEEE-
EEEE-
Field
E- breaks
down
E-
OFF
E-
EE-
E-
E-
E-
Turning the Joule Thief on
• Making the joule thief turn on at night
and off in the morning adds just one
extra component
Hand-wound
ferr ite torroid
A voltage divider is
created by the
addition of the LDR
keeping the
transistor off when
exposed to light
Single Cell
(~ 0.3-1.5V)
10K 
C
B
LDR
2N3904 E
3 Volt LED
LED Flasher
• Two PNP transistors act as switches to
turn on LEDs
+9v
E
2N3906
E
33 K 
B
B
2N3906
47 uF
+
C
+
47 uF
100 K 
C
How it Works: LED Flasher
• An RC circuit triggers the transistors
+9v
E
• Changing the
resistor and
capacitor will
determine the LED
flash rate
2N3906
E
33 K 
B
B
2N3906
47 uF
+
C
+
47 uF
100 K 
C
Materials and Kit Cost
Kit Materials
Quantity Part name
Cost per unit
2
1
2
2
2
1
2
Resistor 390Kž
Resistor 10Kž
High output LED
Capacitor 47µF
Battery Contacts
Light Dependent Resistor
(CDS Cell)
Transistor 2N3906
1
1
Cheapest place to shop
$0.01
$0.01
$0.15
$0.02
$0.07
$0.60
Total cost per
kit
$0.02
$0.02
$0.30
$0.04
$0.14
$0.60
$0.049
$0.098
www.jameco.com
Transistor 2N3904
$0.045
$0.045
www.jameco.com
$0.20
$0.20
1
Toroidal Core
28 gage stranded wire 30”
Printed Circuit Board (PCB)
http://www.goldmine-elec-products.com
www.jameco.com
http://www.kelvin.com
•
14 components, 1 single sided PCB
$0.40
$0.40
Total cost per kit: $1.86
www.jameco.com
www.jameco.com
http://www.goldmine-elec-products.com
www.jameco.com
http://www.allelectronics.com
http://www.goldmine-elec-products.com
PCB/Parts Layout