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.
The A3906 integrated circuit from Allegro MicroSystems (www.allegro.com) consists of a single-step motor...
We found this circuit in a 1980s publication on telephony. The circuit uses an integrated...
This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The...