This circuit was found in the February 1985 issue of Radio Electronics magazine. It is based on an AY-3-1350 melody generator that was common at the time. It is suitable for analog lines only.
We found this interesting timer circuit or CMOS timer in a 1988 publication. The circuit is still...
This circuit can be powered by 2 or 3 small batteries. The resistor can have values between 220...
Found in a magazine 73 for radio amateurs, this circuit operates in the 144 MHz band, at a...