by Philippe Duboisset:
This project is an open source (hardware & software) DDS generator, based on: smart TFT module, AD9834, LM7171 fast amplifier. The homemade function generator is a quite common project on the internet. We can find different ways to do it:
– The quick & dirty way based on a DDS module bought on eBay
– The analog version based on a MAX038 / XR2206
– The clean way based on a FPGA and a fast DAC (e.g. http://www.circuitben.net/node/14)
– The software way (e.g. Arduino + R/2R DAC)
From my side, I wanted a small one which could fits my needs without being too expensive. According to me, such generator should at least:
– Be easy to use
– Output a signal from 1Vpp to 10Vpp (+/-5V), from 0 to 1MHz
– Have a low profile
– Without electric hazard (shall work on a 12V DC)
Tiny DDS – Open source DDS generator - [Link]
Dave explains a big trap in high frequency measurement with your oscilloscope. Based on a viewer request, Dave demonstrates how to incorrectly and then correctly measure the signal output level over frequency of your function generator using your oscilloscope. Some whiteboard transmission line theory is thrown in as well.
EEVblog #652 – Oscilloscope & Function Generator Measurement Trap - [Link]
An all-in-one breadboard with Oscilloscope, Spectral Display, Function Generator, and Power Supply.
We are excited to bring a low-cost audio range electronics development board to classrooms, labs, small businesses, and techno-geeks everywhere. This idea has been bouncing around in our family for many years and now the technology has caught up to make it a reality at a price that schools and individuals can afford. We have paired a traditional prototype board (or breadboard) with an electronics suite so that the experimenter does not have to purchase the expensive electronics test equipment needed during development. It is everything we wish we had when we were learning about circuits on a breadboard.
Bakerboard: The Educational Breadboard with More - [Link]
by Petre Petrov:
This simple, robust, and low-cost signal generator, based on the LM386 power amplifier IC, provides a trio of audio-band signals with three different simultaneous outputs at the same frequency: square/rectangle (SQW), triangle (TRG), and sine (SS).
Audio Function Generator Provides Three Simultaneous Square, Triangle, Sine Waveforms - [Link]
This video reviews the two most common reasons why the output amplitude setting on a function or signal generator doesn’t match what is read on an oscilloscope. This can be due to an incorrect attenuation setting on the scope, but is most commonly due to the fact that the generator is not presented with the load impedance that it is expecting. To correct this most common case, you can either use the correct load impedance, or tell the generator what load you are presenting it with.
Why your Function Generator’s output voltage reading can be wrong - [Link]
This video discusses how to measure the ESR (equivalent series resistance) of a capacitor using an oscilloscope and function generator. All of the capacitors tested in this video were 220uF electrolytic caps. In reality, the resistance in the plates of a dried out electrolytic capacitor can’t be modeled as a simple series resistor, but for the purposes of identifying good from bad, this simplification works fine.
Measure Capacitor ESR with an Oscilloscope and Function Generator - [Link]
Harrymatic @ instructables.com writes:
I was in need of a function generator to produce audio signals for testing effects / amplifiers; as well as TTL clock signals for digital circuits. As function generators generally cost about £200 new, I decided that I would instead build one myself.
This project uses the XR-2206 integrated circuit to generate the waveform. It can produce sine and triangle waves of selectable amplitude and frequency and also a TTL sync signal fixed at 5V. The frequency range is about 20Hz to 300KHz – so this function generator will easily cover the full human hearing range of frequencies.
Analogue Function Generator - [Link]
amandaghassaei @ instructables.com writes:
Waveform generators (also called function generators) are useful for testing and debugging circuits. They can be used to test the frequency response of electronic components like op amps and sensors or to characterize and troubleshoot audio effects boxes and pedals. This waveform generator shield is powered by an Arduino. It outputs four waveforms: sine, triangle, pulse, and saw, each waveform ranges in frequency from 1Hz-50 kHz. The frequency, pulse width, and overall amplitude (gain) of the waveforms is controlled by three potentiometers.
Arduino Waveform Generator Shield - [Link]
manekinen @ mdiy.pl builds a 400KHz function generator based on ICL8038. He writes:
Function generator with adjustable frequency from 0 Hz to over 400 kHz, adjustable amplitude, DC offset, duty, and of course the function selection – square, triangle, and sine. Generator based on good old ICL8038 integrated chip generator that gives pretty good shaped signals as for amateur purposes.
400kHz function generator with ICL8038 - [Link]
The AD9837 is a low power, programmable waveform generator IC capable of producing sine, triangular, and square wave outputs. Below is a circuit design to build your own function generator. The circuit can be connected to a microcontroller through a 3 wire serial interface to set the registers in the waveform generator IC. Package it in a nice enclosure and add some BNC connectors and you have your own Function Generator.