We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer unusual in our day. The transistor is general purpose type.
This is a two-input audio switching circuit. The operational can be of any type and more entries can...
We found this amplifier for automotive use in the Philips integrated circuit manual from 1990. The...
Found in old English documentation this circuit can be made with a BF245 or equivalent. Coils are...