When i was using operational amplifiers at school lab i wanted a function generator at home to play with and work on circuits with Op Amps for better understanding. So i found on the internet a free function generator circuit which uses the IC XR-2206, i printed the PCB with my UV epxosure box, i bought an enclosure box, i put everyhting inside and here is the result.
The function generator can generate Square, TTL, Sine and Traingle waveforms from 1Hz to ~1Mhz with Voltage regulation to Square Sine and Traingle waveforms.
The front panel is a printed cardboard.
Here are some construction photos, taken with my mobile phone before buying a digital camera.
The schematic from the internet
The PCB from the internet