TIMERS: Digital, Mechanical, Multi-timer event | Perfect for scientific demonstration

TIMERS: Variety

(Wikipedia excerpt: ..."A timer (T) or countdown (T) is a type of clock that starts from a specified time duration and stops upon reaching 00:00. An example of a simple timer is an hourglass. Commonly, a (T) triggers an alarm when it ends. A (T)  can be implemented through hardware or software. Stopwatches operate in the opposite direction, upwards from 00:00, measuring elapsed time since a given time instant. Time switches are timers that control an electric switch....

Mechanical (T) use clockwork to measure time.[1] Manual (T) are typically set by turning a dial to the time interval desired, turning the dial stores energy in a mainspring to run the mechanism. They function similarly to a mechanical alarm clock, the energy in the mainspring causes a balance wheel to rotate back and forth. Each swing of the wheel releases the gear train to move forward by a small fixed amount, causing the dial to move steadily backward until it reaches zero when a lever arm strikes a bell. The mechanical kitchen (T)  was invented in 1926.

The simplest and oldest type of mechanical (T) is the hourglass - which is also known as "the glass of the hour" - in which a fixed amount of sand drains through a narrow opening from one chamber to another to measure a time interval...")