Introduction to EngineeringCamera Lab #4 – 1Introduction

Agenda

Objectives of this lab experienceFunctions of the flash circuitReview of Basics- especially capacitorsSchematic diagram of the circuitComparing the real circuit board to the

schematicHow 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.

Acquire experience with the relationship between the actual circuit board in the camera and the "schematic" representation of the circuit.

Lab 4: Objective 2

Acquire experience in using a voltmeter and an oscilloscope to measure voltages in the circuit.

Lab 4: Objective 3

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 4

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.

Lab 4: Objective 5

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 circuitsSymbols 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 of the Flash Circuit

More ComplexCircuitry for

Converting DC to AC

G

A

B

C

2K

2M

Schematic of the Flash Circuit

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