XR2206 frequency generator

...Looks like I have to build all the projects that I didn't managed during my youth.... back then my preferences were power supplies, audio circuits and transmitters.
In the audio department something useful was an audio frequency generator , unfortunately an interesting project back then used a XR2206 IC which cost'd the equivalent to 6 Eur by today's money, that's not much, it was 30 years ago.
So back then the best I could manage was the finger test and check for audio output...

Recently come across one of those chips and decided to give it a go.

Here's the final outcome

It would be cheaper to buy one ready made... half the fun.
Also added an Arduino frequency counter with bubble display.

Inside plenty of space:

...but not everything fitted on the front panel:

And some outputs from it:

..I didn't used the full potential of the chip, it can do also some modulation but left that as a possibility for the future, it also only outputs AC component on the triangle and sinusoidal output.

Schematic was similar this one with small adaptations:

 In the initial testing of the counter code...

In all fairness, do I need it? No. Did I used it already, No... but less one project in my "youth" list.... If I remember still have a multimeter with the ICL7106 and an STK audio amp to do :)

Have a nice week!