Answer Happy

16. The Triangle-Square Generator modified procedure
Objective
In this exercise, a simultaneous triangle-square wave generator is
examined. The investigation will
include the effect of capacitance on output frequency, and the role
of op amp speed in determining ideal
wave shapes.
Theory Overview
The triangle-square generator consists of two main parts: a
comparator and a ramp generator or integrator.
The circuit is self-sustaining by nature. The ramp generator
requires a square wave input. It gets this
signal from the comparator. The comparator in turn generates the
square wave from the triangle wave
appearing at the output of the ramp generator. The output frequency
is determined primarily by the RC
timing values of the ramp generator, and secondarily by the
switching thresholds of the comparator. The
practical output frequency limit is set by the bandwidth and slew
rate of the op amps. At higher
frequencies, slew rate limiting will noticeably slow the edges of
the square wave. This will impact the
output of the ramp generator and will affect both the linearity of
the wave shapes and the output
frequency.
Reference
Fiore, Op Amps and Linear Integrated Circuits
Section 9.2, Op Amp Oscillators
Equipment
(1) Oscilloscope model:________________
srn:__________________
(1) Dual DC power supply model:________________
srn:__________________
(1) DMM model:________________ srn:__________________
Components
(2) Low speed op amps (741)

(1) 100n F actual:__________________ __________________
(1) 1n F actual:__________________
(1) 10n F actual:__________________
(1) 10k  actual:__________________
(1)20k or 22k  actual:__________________
(1) 33k  actual:__________________
Determine the output frequency and amplitudes for the circuit .
Use Vsat = ±13 V.
First, note that the comparator always swings between +Vsat and
−Vsat. Now,
determine the upper and lower thresholds for the comparator.
Vupper thres=V sat R2/R3
Vupper thres=13V x 10 k/20 k
Vupper thres=6.5 V
The lower threshold will be −6.5 V. We now know that the triangle
wave
output will be 13 V peak-to-peak. From this we may determine the
output
period.
Because the ramp generator is driven by a square wave with an
amplitude of
Vsat, Equation 9.24 may be rewritten as
dv/dt =V sat/RC
dv/dt = 13V/33 k×0.01μ F
dv/dt =39,394V/s
The time required to produce the 13 V peak-to-peak swing is
T=
13V/39,394V/s
T=330 μs
This represents one half-cycle of the output wave. To go from +6.5
V to
−6.5 V and back will require 660 μs. Therefore, the output
frequency is
f =1/T
f =1/660μs
f =1.52 kHz
1. Using 10n F for the capacitor, determine the theoretical
output frequency and the peak value of the
triangle wave. Record these items in Table 1.
2. Construct the circuit of Figure 1 using the 10n F capacitor and
the medium speed op amps.
3. Record the output frequency and amplitude of the triangle wave
in Table 1 and determine the
deviation between the theoretical and experimental results.
4. Observe the oscilloscope displaying the triangle and square
waves.
5. Replace the capacitor with the 100n F unit. Determine the
theoretical output frequency and the peak
value of the triangle wave using this new value, and record the
results in Table 2.
6. Record the output frequency and amplitude of the triangle wave
in Table 2 and determine the
deviation between the theoretical and experimental results.
Data Tables

Theoretical
Experimental
% Deviation
fout
Vout
Table 1

Theoretical
Experimental
% Deviation
fout
Vout
Table 2