Functional Description; Theory Of Operation - Elenco Electronics FG-600K Assembly And Instruction Manual

FUNCTIONAL DESCRIPTION

The FG-600 is a function generator integrated circuit capable of producing high quality sine, triangle, and square
waves of high stability and accuracy. A picture of each waveform is shown below:
Sine Wave

THEORY OF OPERATION

The heart of the FG-600 Function Generator is the
XR-2206 monolithic function generator integrated
circuit. The XR-2206 is comprised of four main
functional blocks as shown in the functional block
diagram (Figure 1). They are:
• A Voltage Controlled Oscillator (VCO)
• An Analog Multiplier and Sine-shaper
• Unity Gain Buffer Amplifier
• A set of current switches
The VCO actually produces an output frequency
proportional to an input current, which is produced
by a resistor from the timing terminals to ground.
The current switches route one of the currents to the
VCO to produce an output frequency. Which timing
pin current is used, is controlled by the FSK input
(pin 9). In the FG-600, the FSK input is left open,
thus only the resistor on pin 7 is used.
frequency is determined by this formula:
f = 1/RC Hz
o
where f is the frequency in Hertz
o
R is the resistance at pin 7 in Ohms
C is the capacitance across pin 5 and 6 in Farads
Note that frequency is inversely proportional to the value of RC. That is, the higher the value of RC, the smaller
the frequency.
The resistance between pins 13 and 14 determine the shape of the output wave on pin 2. No resistor produces
a triangle wave. A 200 resistor produces a sine wave.
Triangle Wave
FUNCTIONAL BLOCK DIAGRAM
1
AM Input
Sine/Saw
2
Output
3
Mult. Out
4
V+
5
Timing
Capacitor
6
7
Timing
Resistor
8
The
-11-
Square Wave
+1
Multiplier
and
Sine
Shaper
VCO
Current
Switches
Figure 1
16
Symmetry
Adjust
15
14
Waveform
Adjust
13
12
Ground
Sync
11
Output
10
Bypass
FKS
9
Input