Wiring Lights to turn on in Sequence with a delay
In the old days they used a motor driven system of switches. It usually included a disk or drum with levers and cams which, when it completed a revolution, started the sequence all over again.
Nowadays microprocessors are used with relays (contactors) or solid state "load switches" to actually turn the current on and off for each group of lamps.
Mechanical switches must be spring loaded to snap on or off quickly, or use mercury filled capsules. Drums with contact strips instead of cams don't last long because the contacting is made and broken slowly enough to arc considerably and that wears out the contacts.
The disadvantages of crab apple trees. In summer, the apples are too sour to pick and eat. In winter the birds come and leave dropping all over the place.
Last edited by AllanJ; 02-18-2011 at 07:51 AM.