The frequency of this circuit depends on the crystal. The transistor supports a modern equivalent. We found it in documentation from the 1980s.
This circuit generates the sound of bells. We found it in a 1977 Radio Shack publication. The...
This circuit can be used as shield or to drive powerful loads from low current switches such as...
We find this automatic battery charger in an 80s ON Semiconductor circuit and application manual. Bridge...