This kit contains seven different timing modes using only ONE IC and some support components on a single-sided PCB. It features an opto-isolated trigger input and a relay output.

Timing Modes:
1. Instant On, Delayed Off, Level triggered
    Trigger signal operates the relay and starts the timing cycle. The relay
    remains operated for the selected delay time then releases. Loss of timing
    signal causes the timing cycle to stop immediately and the relay to
    release.
2. Instant On, Delayed Off, Edge triggered
    Same as Mode 1 except Loss of trigger signal does not affect the timing
    cycle. Applying another trigger signal before end of cycle will restart
    the timer
3. Delayed On
    Trigger signal starts the timing cycle. At the end of the delay the relay
    operates and remains on until trigger signal is removed. Loss of trigger
    signal during the delay aborts the timing cycle.
4. Instant On and Hold, Delayed Off
    Trigger signal operates the relay. The relays remain operated while the
    trigger signal is present. Loss of signal starts timing cycle.
5. Toggling
    Trigger signal operates the relay for selected delay time. The relay then
    releases for the same delay time. This cycle continues until loss of trigger
    signal or reset
6. Instant On, Delayed Off, with Pause
    Similar to Mode 0. A trigger signal operates the relay and starts the timing      cycle. However loss of trigger signal causes the timing cycle to pause -
    the relay remains operated. Re applying the signal will restart the delay
    time from where it was stopped. At end of delay time the relay releases.
7. Delayed On with Pause
    Trigger signal starts the timing signal. At the end of the delay time the
    relay operates for 2 seconds. Loss of trigger signal causes the timing
    cycle to pause. Re applying the trigger signal restarts the timing cycle
    from where it was stopped. Reset is the only way to exit this mode.

Delay Ranges:
1. 1 - 255 seconds in steps of 1 second
2. 10 - 2550 seconds (42min 30sec) in steps of 10 seconds
3. 1 - 255 minutes (4hr 15min) in 1 minute steps
4. 10 - 2550 minutes (42hr 30min) in 10 minutes steps

This timer has heaps of possible applications including
   Watchdog Timer
   Timer for Watering Gardens
   Photographic Timer
   Timer for Eprom Eraser
   Motor Control
   Lighting

The timing modes and delay ranges are selected by on-board DIP switches. There is provision for another timer mode. If you can think of another timer variation (or even a completely different set of timing modes) then let us know - it's only a software change! Various triggering options available (see documentation). 12VDC operation. 96 x 48mm - (3 3/4" x 1 7/8") PCB.

Featured in April 2002 issue of Silicon Chip (click for article).