This circuit mimics the trill of a bird. We found it in an American documentation from the 90s. It is based on the LM3909 integrated circuits.
This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The...
Figure bellow shows another configuratíon for a Iow-frequency sine wave oscillator using CMOS...
Found in an 80's documentation this circuit uses an integrated from the uncommon era today. Other...