Introduction to Engineering
Camera Lab #4 – 1
Introduction
Agenda
Objectives of this lab experience
Functions of the flash circuit
Review of Basics- especially capacitors
Schematic diagram of the circuit
Comparing the real circuit board to the
schematic
How the circuit works
Lab 4: Objective 1
 Learn what the core and auxiliary
functions of the flash circuit are and
what the circuit must do to perform
them.
Lab 4: Objective 2
 Acquire experience with the relationship
between the actual circuit board in the
camera and the "schematic"
representation of the circuit.
Lab 4: Objective 3
 Acquire experience in using a voltmeter
and an oscilloscope to measure
voltages in the circuit.
Lab 4: Objective 4
 Be able to calculate currents flowing in
certain parts of the circuit using the
measured voltages together with the
values of parameters of some of the
components.
Lab 4: Objective 5
 Develop an understanding of how and
why the speeds of various parts of the
flash circuit are related to the speeds of
other parts of the camera.
Core Functions of the Flash Circuit
1. Provide a flash of light
 A pulse of more than 1000 volts required to
set off the flash
 Pulse must be synchronized with the shutter
 Pulse comes from capacitor
 HINT: Don’t touch capacitor!
2. Charge the capacitor
 I.E. Convert the stored chemical energy in the
1.5 volt battery to stored electrical energy in
the capacitor where it can be released quickly.
Auxiliary Functions of the Flash Circuit
1. Turn on the neon indicator light when the
capacitor is charged (when the flash can
be used).
2. Automatically recharge the capacitor
after the flash is used.
Basics Concepts Needed for Lab #4
Calculating voltage and current in circuits
Symbols for power source, resistors,
capacitors, etc…
Parallel and series combinations of circuit
elements
How a Capacitor Works
 Made of two plates separated by an insulator
 No current flows from one plate to the other
because of the insulator
 Current flowing into a capacitor (from battery)
causes the charge in the capacitor to build up
 With a 1.5 volt battery, it takes several seconds
to build up the charge
 Capacitor discharges quickly (in milliseconds)
when a circuit is created between the 2 plates
More on Capacitors
 Charge (Q)=Voltage (V) X Capacitance (C)
 Q measured in coulombs
 C measured in farads (or µ farads)
 Electric potential energy (U)
 U = ½ CV2
 U measured in Joules
 C measured in microfarads
Schematic
Schematic of the 2KFlash Circuit
of the
Flash
More Complex
Circuitry for
Converting DC to AC
Circuit
G
B
C
2M
A
Note: Kodak has made several changes in
the flash circuit. Since the circuit boards
are recycled, the circuit board in your
camera may be different than the one
shown here.
Picture of the Flash Circuit
VIDEO: Demonstration of
Camera Lab 4
Assignment
 Read the pre-lab description of an oscilloscope
and do pre-lab assignment #1 & #2
 Read very carefully the procedure for Camera
Lab #4 procedure through Task #1