DIY Function Generator using XR2206 Kit : 1Hz-1MHz

Overview

A function generator is essential for electronics labs, but its high cost can be prohibitive for many hobbyists. There are numerous DIY designs available, with the most popular and affordable Chinese kit featuring the XR2206 function generator chip. From my experience, the easy-to-assemble 1Hz-1MHz XR2206 kit enables various standard measurements and experiments while providing reasonably stable and accurate waveforms. It’s more than sufficient for a modest home electronics hobby lab!

The XR2206 Function Generator Kit is a user-friendly DIY kit for constructing a frequency generator that creates sine, triangle, and square waveforms with frequencies between 1Hz and 1MHz. This guide will help you assemble and use the XR2206 Function Generator Kit effectively.

Components Required

1. XR2206 Function Generator Kit (includes the XR2206 IC, PCB, and other components like resistors, capacitors, and potentiometers)
2. 9V or 12V DC power supply
3. Oscilloscope
4. Soldering iron and solder
5. Wire cutter and stripper
6. Jumper wires and/or BNC connectors for output

XR2206 IC

The XR-2206 is a single-chip function generator capable of producing high-quality and stable sine, square, triangle, ramp, and pulse waveforms with great accuracy. These output waveforms can be modulated in both amplitude and frequency by an external voltage.

Its operational frequency ranges from 0.01Hz to over 1MHz, making it ideal for communications, instrumentation, and function generator applications that require sinusoidal tones, AM, FM, or FSK generation. The XR-2206 has a typical drift specification of 20ppm/°C, and its oscillator frequency can be linearly swept across a 2000:1 range using an external control voltage while maintaining low distortion.

Features

• Low-Sine Wave Distortion, 0.5%, Typical
• Excellent Temperature Stability, 20ppm/°C, Typ.
• Wide Sweep Range, 2000:1, Typical
• Low-Supply Sensitivity, 0.01%V, Typ.
• Linear Amplitude Modulation
• TTL Compatible FSK Controls
• Wide Supply Range, 10V to 26V
• Adjustable Duty Cycle, 1% TO 99%

Applications

• Waveform Generation
• Sweep Generation
• AM/FM Generation
• V/F Conversion
• FSK Generation
• Phase-Locked Loops (VCO)

XR2206 Function Generator Kit Assembly

Upon purchasing the DIY kit, some soldering work is necessary, but it includes all components required for the project.

The kit features through-hole components, and the double-sided PCB is marked with legends that clearly indicate where to mount and solder each part. Furthermore, the kit provides a high-quality socket for the XR2206 chip, stylish caps for the jumpers, and knobs for the potentiometers.

Circuit Diagram

Soldering Tips

1. Solder the components on top of the board in order of height, starting with the lowest components such as capacitors, resistors, and diodes.
2. Proceed to solder the IC socket, terminal blocks, and finally the power socket and adjustable potentiometers.
3. Use diagonal cutting pliers to trim the excess pins on the back of the board as closely as possible.

Soldering Process

1. Begin by identifying all components included in the kit. You should have the XR2206 IC, a printed circuit board (PCB), resistors, capacitors, potentiometers, and other necessary components.



2. Solder the resistors, capacitors, and other small components onto the PCB, paying close attention to their values and orientations. Use the kit’s provided schematic or assembly guide as a reference.
3. Solder the XR2206 IC socket onto the PCB, ensuring that the notch or dot on the socket aligns with the marking on the PCB. This will help you correctly insert the XR2206 IC later.



4. Insert the XR2206 IC into the socket, aligning the notch or dot on the IC with the marking on the socket. Press down gently to ensure proper seating.
5. Solder the potentiometers for frequency and amplitude control onto the PCB. These will allow you to adjust the output frequency and amplitude of the waveforms.



6. Attach a power connector or solder wires directly to the PCB for the power supply input. Make sure to connect the positive and negative terminals correctly.
7. Connect the output to a BNC connector or solder wires for connecting the output to an oscilloscope or other testing equipment.

Testing and Usage

Connect the power supply to the XR2206 Function Generator. Be sure to use a 9V or 12V DC power supply as specified by the kit.

Connect the output to an oscilloscope or other testing equipment using jumper wires or a BNC connector. In this testing part, I am using a simple portable oscilloscope. If you don’t have an Oscilloscope, you can you make your own DIY Oscilloscope using Raspberry Pi Pico & Smartphone.

Turn on the power supply and adjust the potentiometers to select the desired waveform, frequency, and amplitude.

Observe the output on the oscilloscope, and fine-tune the potentiometers as needed to achieve the desired waveform and frequency range. Using the following setting you can generate various waveforms and change the settings.

Waveform Specifications

1. Sine Wave

• Amplitude: 0-3V with 9V DC input
• Distortion: Less than 1% (at 1kHz)
• Flatness: +0.05dB from 1Hz to 100kHz

2. Square Wave

• Amplitude: 8V (without load) with 9V DC input
• Rise Time: Less than 50ns (at 1kHz)
• Fall Time: Less than 30ns (at 1kHz)
• Symmetry: Less than 5% (at 1kHz)

3. Triangle Wave

• Amplitude: 0-3V with 9V DC input
• Linearity: Less than 1% (up to 100kHz) at 10mA

Output Waveforms

The square wave looks like this.

The sine wave can be tuned to form perfect wave.

You can also produce triangular waveform.

The frequency selection jumper can be adjusted as follows to generate different frequencies.

Once you have achieved the desired output, you can use the function generator in various applications, such as testing electronic circuits or audio equipment.