Triangle Wave Generator

Lakehead University

Faculty of Engineering
Department of Electrical Engineering

Engineering 2132

Electronics II

EXPERIMENT #2

TRIANGLE WAVE GENERATOR

Name: Angelo Garangau Menezes

Student ID: 0578114

Date of performance: October 16th, 2015

Partner: Gracieth Cavalcanti Batista

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ABSTRACT

        Objective: To analyze the behavior and characteristics of a circuit with a triangle wave generator using a voltage comparator utilizing hysteresis and an integrator.

        Theory:

        Combining op-amps can bring vary number of functions, one of them is the generation of triangle wave forms from square wave inputs as it is used in function generators with the combination of a comparator and an integrator.

        A triangle wave generator works with a constant voltage at the input of an integrator being applied to get a voltage that might rise or fall as a ramp does. According to the hysteresis referent to a comparator, this voltage can become the ramp in a square wave that is fed back as the input for the first op-amp as can be seen in figure 1.

        

[pic 1]

Figure 1: Circuit with integrator and comparator op-amps

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SCHEMATIC DIAGRAMS

[pic 2]

Figure 2: Part A Circuit – Schmidt trigger with hysteresis circuit

[pic 3]

Figure 3: Part B Circuit – Integrator Circuit

[pic 4]

Figure 4: Part C Circuit – All parts together

EQUIPMENT IDENTIFICATION

Oscilloscope;

Function Generator;

Variable power supply

Digital Multimeter;

Parts (Resistors, Capacitors, LM741 …) and cables as required.

PROCEDURE

Part A – Schmidt trigger with hysteresis

1. The circuit board shown in figure 2 was set for R1 = 3.3 KΩ and R2 = 3.9 KΩ.
2. Digital voltmeter was connected to input and scope to the output of the op-amp.
3. Vin was set to -15V and gradually increased in unit steps until +15V with the output being recorded in order to check its status as high or low. This process was repeated decreasing Vin until -15V still recording the status of the output in 1 volt decrements.
4. The measurements were made for R2 = 8.2 KΩ, 18 KΩ, and 39 KΩ.
5. For analyzing the circuit response for a triangle wave generator, R2 replaced to be 8.2 KΩ, the potentiometer was removed and the function generator was connected to the input resistor R1 with a triangle wave of 20 Vpp and 1 KHz. Then, the scope was connected to the function generator by Chanel 1 and to the output of the circuit by Chanel 2 to take waveform measurements and analysis. The wave format could be seen as triangle such as in figure 5.
6. [pic 5]
7. Figure 5: Triangle Waveform

1. The same procedure and measurement were applied for R2 = 18Ω, 39Ω.

Part B – Integrator

1. The circuit in figure 3 was set.
2. The function generator was set to a 2 Vpp voltage at 1 KHz frequency.
3. The gain (slope of the waveform) of the output was measured to be compared with the relative theoretical values.

Part C – All parts together, the triangle wave generator

1. The circuits of Part A and Part B were connected as shown in figure 4.
2. The relative frequency of oscillation was measured and recorded.

EXPERIMENT AND ANALYSIS

,[pic 6]

[pic 7]

[pic 8]

[pic 9]	[pic 10]
-15 to 11 Volts (1 volt steps)	-14V
12 to 15 Volts (1 volt steps)	14V

Table 1:  increasing from -14V to 15V in 1V steps.[pic 11]

[pic 12]	[pic 13]
15 to -11 Volts (1 volt steps)	14V
-12 to -14 Volts (1 volt steps)	-14V

Table 2:  decreasing from 15V to -14V in 1V steps.[pic 14]

,[pic 15]

[pic 16]	[pic 17]
-15 to 5 Volts (1 volt steps)	-14V
6 to 15 Volts (1 volt steps)	14V

Table 3:  increasing from -15V to 15V in 1V steps.[pic 18]

[pic 19]	[pic 20]
15 to -5 Volts (1 volt steps)	14V
-6 to -15 Volts (1 volt steps)	-14V

Table 4:  decreasing from 15V to -15V in 1V steps.[pic 21]

,[pic 22]

[pic 23]	[pic 24]
-15 to 2.4 Volts (1 volt steps)	-14V
2.5 to 15 Volts (1 volt steps)	14V

Table 5:  increasing from -15V to 15V in 1V steps.[pic 25]

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