This countdown electromagnetic ring launcher was found in an Electronic Hobbyst Handbook from 1993. The components can be difficult to obtain. Details of the launch coil were not given.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...