Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic baths in developing rooms but can be used for other purposes. The circuit beeps at 30-second intervals.
The indicated circuit is an intermittent one in which we use two 555 integrated ones, one as a low...
Found in an Electronic Design from the 90s, this circuit modifies the phase of a signal in 8...
In the figure we have the way to use a low-cost digital clock chip to trigger an alarm. The...