The circuit shown was found in the February 1994 issue of Electronics Now magazine. The circuit records messages for a few seconds and plays them back as keys are selected.
Found in National Semiconductor documentation from the 1990s, this circuit corrects the curvature of...
Developed by Philips this 60's circuit uses a transistor of the time, but the configuration holds true for...
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...