Simple Function Generator Circuit using IC L8038

An integrated circuit called the IC L8038 is used to produce somewhat twisted waveforms such as sine, square, and sawtooth waves.

It functions by adjusting the frequency, which is adjustable between 0.001Hz and 300 KHz using an external timing capacitor and resistor.

It is able to modulate and sweep frequencies using an external voltage input.

High linearity, robust output levels, and simultaneous production of sine, square and sawtooth waves are other characteristics.

It also has a low number of external components and stability throughout a broad temperature range.

Circuit Working:

Parts List:

For functioning this circuit, a dual supply of positive 10V DC is needed you may build this circuit on a vero board using a power source that is well regulated and filtered is essential.

Using internal current sources, the circuits external timing capacitor C2 is charged and discharged.

While the other current source is turned on and off by a flip-flop, the first runs continually.

Capacitor C2 charges linearly with time while the first current source is on and the second is off.

The flip-flop starts to operate, turning on the second current source, when the voltage across C2 approaches two thirds of the supply voltage.

Due to the doubled current from this source, capacitor C2 will drain linearly until the voltage falls to one-third of the supply voltage.

The flip-flop resets at this moment, resuming the cycle.

The IC L8038 is used in the circuit schematic to create a variable audio frequency oscillator, which is useful for testing audio related tasks.

It operates in the frequency range of 20 Hz to 20 KHz.

Pot VR2 is used to adjust the oscillators frequency, while Pot VR4 is used to change the distortion levels.

The duty cycle is adjusted by Pot VR1, and any deviations are made up for by Pot VR3.

R3 is used as a pull-up resistor, while C2 is the external timing capacitor.

Formulas:

When creating a circuit for a Simple Function Generator that uses the IC L8038, the following important formula are used:

Frequency (f):

The following formula may be used to find the oscillation frequency produced by the IC L8038:

f = 1.2​ / (R * C)

where,

• The timing resistor is represented by R is usually a fixed resistor or potentiometer.
• C2 is the timing capacitor represented by C.

Duty Cycle Modification:

Resistor RDuty may be used to change the duty cycle of the square wave output when it is connected between pin 4 and 5

Duty Cycle = R_Duty​​ / R

where,

• R is the timing resistor.

When constructing a function generator using the IC L8038, these formulas and controls let you adjust the output waveform parameters (frequency, duty cycle, and distortion) to your specifications.

Changes made to resistors R, RDuty​, RDist​ and the timing capacitor C will have an immediate impact on the waveform characteristics as stated.

How to Build:

To build a Simple Function Generator circuit using IC L8038 follow the below mentioned connections steps:

• Assemble all the components as shown in above circuit diagram
• Connect pin 2 of IC L8038 to the output of an oscilloscope of sine wave
• Connect pin 3 of IC L8038 to the output of oscilloscope of sawtooth wave.
• Connect pin 4 of IC L8038 to first leg of pot VR1 through resistor R2.
• Connect pin 5 of IC L8038 to third leg of pot VR1 through resistor R1.
• Connect diode D1 from center leg of VR1 pot to positive supply.
• Connect pin 6 of IC L8038 between center leg of VR1 pot to diode D1.
• Connect pin 8 of IC L8038 to center leg of pot VR2, connect 1st leg of VR2 pot to positive supply and 3rd leg of VR2 pot to ground through resistor R4.
• Connect a capacitor C1 from pin 8 of IC L8038 to positive supply
• Connect pin 9 of IC L8038 to the output of oscilloscope of square wave and connect a resistor R3 from pin 9 to positive supply
• Connect pin 10 of IC L8038 to ground through capacitor C2.
• Connect pin 11 of IC L8038 to ground.
• Connect pin 12 of IC L8038 to first leg of VR4 pot and center leg of VR4 pot to ground.

Safety Measures:

When experimenting with the Function Generator circuit, keep in mind that by following to safety precautions, you may reduce the possibility of component damage and guarantee safe operation.

Conclusion:

The IC L8038 based Simple Function Generator circuit provides a flexible and efficient way to create a range of waveforms, including sawtooth, square, sine, triangle, and pulse waves.

It is a dependable option for applications needing accurate waveform production in testing, prototyping, and teaching contexts because of its simple design and steady performance.

References:

Precision Waveform Generator/Voltage Controlled Oscillator