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.
With the original components, suggested in a Motorola documentation from 1971, this circuit can...
The first circuit, shown in the figure, generates a stepped signal whose frequency depends on the...
27 MHz Transmitter (CB14008E) This circuit was found in a Japanese publication from the 1970s. The...