How to Generate Sine, Triangle, and Square Waves Using ICL8038?

Pin No	Pin Name	Type	Description
1	VCC	Power	Module Supply Voltage
2	GND	Power	Ground Connection Pin
3	AG	Analog Output	The output pin that's best suited for receiving the sine and triangle waves.
4	G	Power	Ground Connection Pin
5	DC	Digital Output	The output pin that's best suited for receiving the Square waves.

The supported input voltage range is approximately 10 to 30V maximum. However, 30V is not recommended as it will eventually increase the operating temperature. An optimum of 12V is suggested for better operation.

The output can be drawn in two forms: one as a pure analog wave and the other as a DC-biased voltage. Each has its unique advantage. Analog output is best suited for sine wave output, while DC output is best suited for triangle and square wave outputs.

Next, we will continue with the configurations.

Configurations available in ICL8038 Module

Typically, there are two configurations available in the ICL8038 module: frequency range selection and waveform type selection. The image below shows the exact shunt jumper positions that need to be adjusted to select the correct configuration, along with a small table describing the available configurations.

Part No	Part Name	Description
1	5 way - Shunt Jumper	For Configuring Frequency Range
2	3 way - Shunt Jumper	Configuring Output Wave Type

One thing to remember is that selecting the correct frequency range is important to achieve the desired output. Ideally, try to position the desired frequency in the middle of the range to allow smooth adjustments and ensure a stable output. For example, if you need 100Hz, a range of 10Hz to 450 Hz is suitable. If you need 100kHz, a range of 6kHz to 120kHz is recommended.

Finally let's look at the controls available to tune the wave form.

Controls Available in ICL8038 Module

This module has all the major tuning options, allowing us to easily modify the signal’s waveform. Below, you can see the part-marking image of all the components that assist in tuning the signal, along with a table representing each control option and its scope of operation.

Part No	Part Type	Controllable Waveform	Description
1	Trimmer Potentiometer	All	Duty Cycle Adjustment
2		All	Frequency Adjustment
3		Square Wave	Linear Regulation
4		All	Output Amplitude Adjustment
5		Sine Wave	Linear Adjustment

Here is some information I would like to add,

Duty cycle adjustment, frequency adjustment, and amplitude adjustment are common for all types of waveforms. However, linear regulation or adjustment is an additional feature for square and sine waves.

Except for amplitude adjustment, every other control has some influence on the signal's frequency. So, be cautious when setting the correct frequency for your application.

Schematics of ICL8038 Module

Finally, here is the schematic, which is essential for understanding, recreating, or modifying the ICL8038 module. Below is the complete schematic diagram of the module.

Starting with the Power Section, the input voltage is passed directly to the circuit without any regulation. Before reaching the circuit, the voltage goes through two filter capacitors to prevent surges. Additionally, there's a power indicator LED near the input.

You can also adjust the frequency of the output waveform by altering the input voltage at the FM Sweep Pin of the ICL8038. This changes the charge and discharge timing of the capacitor, affecting the output frequency.

There are two separate circuits to adjust the waveform: one for sine wave linearity and another for duty cycle adjustment. Specifically, you use the R13 potentiometer to fine-tune the linearity of the sine wave and the R12 potentiometer to adjust the duty cycle of all waveforms.

Finally, we have the Output Section. The module generates three waveforms simultaneously (sine, square, and triangle). You can select the desired waveform using a shunt jumper(P2). The selected waveform is amplified by a general-purpose NPN transistor (Q1). The amplitude can also be adjusted using the R14 potentiometer. Additionally, the R15 potentiometer, connected to the base, is used to adjust the linearity of the square wave that doesn't affect other waveforms..

For the outputs, the module provides two options—AC and DC. Typically, DC output is preferred for square and triangle waveforms, while AC output is more suitable for sine waveforms. You can choose the appropriate output based on the selected waveform and your specific needs.

Next Let's see about the Controlling and its Relative Output.

Guide Tuning the Output Signal

Here, I will show all the configuration and tuning options along with the output recorded from the oscilloscope. As we know, there are three different waveforms, and among these, there are four different controls, except for the triangle waveform, which has three controls. Starting with the sine waveform.

Remember: Every GIF has two signals, one in yellow and another in blue. The yellow signal is the DC output, while the blue signal is the analog output. All footage is taken while providing 12V to the ICL8083 module. The GIFs are recorded while rotating the respective potentiometer.

SineWave - Amplitude Adjustment

Below is the waveform captured while adjusting the amplitude trimmer potentiometer. As you can see, we get an approximate output range of 320 mV to 5.12 V with an input voltage of 12 V. Although the DC output (yellow wave) appears similar to the AC wave, the key difference is that the analog output has a proper offset over the signal period, while the DC output is most likely a true DC output.

 

 

Therefore, it is recommended to use the analog output for the sine wave.

SineWave - Frequency Adjustment

It is generally observed that adjusting the potentiometer changes the frequency within the selected range. However, if you turn the potentiometer to either end, the output will be null. It is better to keep the potentiometer in the middle position. Additionally, the frequency is not stable at the ends of the potentiometer's range.

 

 

SineWave - DutyCycle Adjustment

There is generally no need for duty cycle adjustment in a sine wave. However, here is what happens when you adjust the duty cycle while in sine wave configuration.

 

 

Ensure that the duty cycle is set to approximately 50% to maintain a proper sine wave.

SineWave - Linearity Adjustment

In the sine wave configuration, adjusting the linearity allows you to modify the timing between the positive and negative cycles.

 

 

In most cases, it should be kept close to 50%. Only under special conditions would you need to adjust the linearity to either end.

TriangleWave - Amplitude Adjustment

Now we switched to the triangle wave form output. Here Amplitude adjustment is as usual. And similar ranges of voltage like sine wave has observed.

 

 

In the GIF above, you can clearly see that the DC output (yellow wave) provides the best triangle waveform. Therefore, it is best to use the digital bias output for the triangle wave.

TriangleWave - Frequency Adjustment

As with the sine wave, adjusting the frequency of the triangle wave produces similar results.

 

 

Also, remember to avoid tweaking the ends of the potentiometer, as the output will be null at those extremes.

TriangleWave - DutyCycle Adjustment

An interesting observation is that while adjusting the duty cycle in the triangle wave configuration, you can obtain two additional waveforms: the positive ramp and negative ramp.

 

 

In the GIF above, you can see three types of waveforms, the sawtooth negative ramp, the triangle wave, and the sawtooth positive ramp.

SquareWave - Amplitude Adjustment

In the square wave configuration, the DC output (yellow wave) provides a more appropriate square waveform. Therefore, it is suitable to choose the DC output for the square wave.

 

 

Regarding the output voltage range, we successfully achieved 320 mV to 7.6 V, which is slightly higher than the sine wave. As usual, a 12V input voltage is given to the module.

SquareWave - Frequency Adjustment

Similar to the other waveforms, the result is the same when adjusting the frequency of the signal.

 

 

SquareWave - DutyCycle Adjustment

Here, I have a slight disappointment because, as shown Below GIF video, the output signal does not cover the duty cycle range specified in the datasheet of the ICL8038 IC. which is 2% to 98%.

 

 

So, some fine-tuning of the circuit might be necessary.

SquareWave - Linearity Adjustment

While adjusting the linearity of the square wave signal, we observe that it only affects the amplitude of the signal. The purpose of this adjustment is unclear, as we already have a separate potentiometer for adjusting the amplitude.

 

 

Application of ICL8038 Frequency Generator Module

Due to its ability to generate multiple types of waveforms, there are a variety of applications. Let's explore a few,

1. Signal Generation
   Used as a function generator to create sine, square, triangle, sawtooth, and pulse waveforms for testing and troubleshooting circuits.

2. Modulation System
   Helps generate carrier signals for Amplitude Modulation (AM) and Frequency Modulation (FM) systems. It is also useful for testing communication circuits.

3. Audio Testing
   Useful for generating audio signals to test speakers, amplifiers, and audio processing circuits.

4. Oscillator Circuits
   Acts as a tunable oscillator in electronic circuits that require a variable frequency source.

5. Waveform Analysis
   Assists in simulating and analyzing different types of waveforms in research, teaching, and laboratory setups.

6. Pulse Width Modulation (PWM)
   With adjustable duty cycles, it can be used in applications requiring PWM control, such as motor control or dimming LEDs.