This instructable describes the design of function generator based on the Maxims’s Analog integrated circuit MAX038.
The function generator is very useful tool for the electronics freaks. It is needed for tuning resonance circuits, testing audio and video equipment, designing of analog filters and for many other different purposes.
Today there are two main types of function generators ; digital, (DSP based, DDS…) which are more and more often used and analog, which were the origins.
Both types have their advantages and disadvantages. The digital generators can generate signals with very stable frequency, but they have problems with generating very pure sine signals (what is not problem for analog one). Also the mainly spread function generators based on DDS approach have not so big frequency generation range.
Since long time I wanted to design a useful function generator, which could somehow combine some of the advantages of both types (analog and digital) generators. I decided to base the design on the Maxim chip MAX038*
* Remark – this chip is not more produced and sold by Maxim. It is obsolete. It is still possible to find it in eBay, Aliexpress and other sites for electronic components.
There are existing also other analog function generator chips (XR2206 from Exar, icl8038 from Intersil), but I had
one MAX038 available, and I used it. The digital features of the function generator were performed by one Atmega328 chip. Its functions are the following:
- controls the frequency range selection
- controls the signal type (sine, rectangular, triangular, sawtooth)
- measures the amplitude of the signal
- measures the DC offset
- measures the frequency of the signal
- measures the THD of the sine signal in the audio range (this still have to be implemented)
- displays all this information on a character 16×2 LCD display.
For more detail: Function generator