This circuit can keep a set of lamps on for up to 1 minute, time given by C2 and R2 that can be changed. The load depends on the relay. The circuit is old, from 1988 documentation, but totally viable today.
This sophisticated sinusoidal audio signal generator uses a Wien bridge configuration with an...
This defrost alarm starts from an interesting idea. A small magnet on an ice stone is trapped at the...
Many reed switches can be wired in series to perform na efficient alarm as shoen in the figure....