Pr Inciples Of Operati On - Ci Rcu It Descri Ption; General; Block Diagram Princliples Of Operation - Vivitar 283 Service Manual

2.1
•
SECTION 2
Automatic Electronic Flash
Model 283
PRINCIPLES OF OPERATION - CIRCUIT DESCRIPTION
GENERAL
The Vivitar Model 283 Auto Electronic Flash Unit provides a source of variable-duration, high-intensity
light, keyed to preset camera f-stops and automatically compensating for distance by means of auto control
circuitry. In any of the four automatic modes of operation, flash duration and intensity are automatically
controlled. The manual mode furnishes constant, maximum light output.
The major circuits of the unit are oscillator, rectifier and power storage, flash trigger, quench, light sensing,
bounce compensator (BCC), and auto control. There is a neon indicator circuit for the ready light, the cal·
culator dial light, and the sufficient light indicator light. The Model 283 operates from a battery or AC
power source. See Figures 2·1 and 2·2.
POWER SUPPLY ANO STORAGE
r--------------- -,
I
I
L_
Oscillator
01 02 T1
Battery
Saver
SCR1 R6
Rectification
2
Storage
03
04 Cl
I
I
I
I
I
I
I
I
I
I
-----------~-- -~
I
I
I
I
I
I
0
BCC
C15 C16
s voe
120
vAc
Trigger
T2
Auto
Control
R26
03 012 SCR3
Open Flash
Button
Hot
Shoe
Quench
OT1 SCR?
light
Sensor
Q4
PC Cord
Figure 2-1. Block Diagram, Principles of Operation
Vivitar 37460599 (11/80)
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