Thursday, 31 January 2019

Update on Digital Audio Siggen

I have made what I hope will be the last update to the Digital Audio Siggen. This is to use an LM386 as the output amplifier. I bought an amazing kit for £1.56 on eBay, a complete amplifier with gain control!!! So the schematic is now this:

ASG sch

If I decide to build this, I may do a PCB. This is the hard wired prototype.

IMG 0883

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

Sythesised Audio Oscillator

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.

IMG 0835
And here's the mockup

IMG 0834

Code here.