Thursday, 31 January 2019
If I decide to build this, I may do a PCB. This is the hard wired prototype.
The output is up to a little above 10dBV up to 100kHz - pretty good for the LM386!
Later I found that 12V was too much for the LM386 I had an it blew up - seems you need a special version fo ruse at 12V and above. So I have removed the amplifier for now.
Code update here
Sunday, 6 January 2019
While many struggle to build audio signal generators using phase shift networks, voltage and gain stabilisers and bunches of op-amps, there is another solution. Digital synthesis.
The AD9833 is an IC designed for generating Sine, Triangle or Square waves from 0Hz up to +10MHz. It is simple to use with an Arduino to build a variable frequency sine wave generator. Combined with a Rotary Encoder and an OLED display an accurate audio generator can be made for about 20€!
Here's the circuit.
And here's the mockup