A clock in a custom carved hardwood box.

This clock is intended to be a surprise to visitors, who activate the clock's display by removing the lid.


The lid has 2 powerfull magnets glued underneath which are capable of magnetizing the mechanism of a watch which comes close, causing it to stop.


This device is battery-operated, self contained, and uses a LCD display with LED backlighting. Since the display uses 50+ MA it is normally off. The magnets in the lid activate a reed relay. On lifting the lid this opens, causing power to be applied from its battery to the board and display.
The only control is underneath tjhe panel. It is a 3-way slide switch to set the hour one hour ahead for pacific DST or stardard mountain time, or 2 ahead for Mt. DST.

It is made with three sub-assemblies:
The controller is the "wsDuino" board, sold as a kit. I has an ATMerga328P micro-controller and a DS-3231 temperature-compensated real-time clock with temperature readout
The display is a 2x16 character transmissive LCD, white-on-black with white LED backlighting.
The power assembly contains a power switch controlled by a reed switch, and provision for measuring the battery voltage.

These are the photos of the finished clock.

Here is the Arduino sketch.

Here are the circuit diagrams.