Despite being found in a 1980 publication, this circuit uses components that can still be found easily. The circuit feeds an array of LEDs that run randomly, stopping at one.
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...